noise."Mechanic: F150 Air Conditioning Inoperative · 1:55am May 24th, 2021
I promise, we’re gonna talk about that big stupid F350 dually and the big stupid 6.4L diesel engine I replaced over the period of several weeks, but for reasons y’all will find out, I want to be sure it’s really fixed before I say anything about it.
Instead, we’re going to talk about automotive air conditioning.
The basics of air conditioning you need to know is that by controlling the pressure of specific gasses, you can make them take heat from one place to another. You have an evaporator on the cooled side, which is where the liquid evaporates and essentially sucks up a bunch of heat, then you have a condenser on the outside, where it condenses and lets all that heat go to the atmosphere. Pressure changes through a valve (expansion valve or metered orifice, usually), and a compressor pushes the gas/liquid along (it’s a gas when it goes through the compressor). Your refrigerator and home AC use the same principles, but not necessarily the same gas, as do most dehumidifiers. Most home appliances run off electricity, with an electric compressor, whereas most automotive AC compressors are belt-driven from the engine.
While it’s not particularly relevant to the vehicle at hand, because the interior of an automobile is a confined space, the refrigerant used can’t be something that will potentially kill the occupants if there’s a leak inside the cabin (one of the issues with a C02-based system), and in the event of a crash it also can’t be particularly flammable or explosive.
In terms of controlling it, most automotive systems have a magnetic clutch to engage the drive belt or not. In older cars, there was just a switch in the control head that turned on the compressor when you pushed the AC button.
Since those systems were old and dumb, there were one or two cut-out switches. One was for high pressure, one for low. If the pressure gets too high, something is going to fail, and in fact most automotive systems have a pressure-relief valve on the AC compressor in case the switch doesn’t work. I’ve seen one blow off, and it makes a mess.
There’s also a low-pressure cutout, and in a lot of the older systems that was the primary control. The AC compressor cycled based on the low-pressure switch turning on and off, usually around 20psi.
[Not that it matters for this particular blog post, but if you’re diagnosing a R134a system in an automobile, resting pressures should be approximately the same value as the temperature in Fahrenheit (if it’s 70F, the high and low side should both be at about 70psi), and when it’s running the high side should be around a hundred plus ambient (so in the previous example, 170psi) . . . I don’t know what the rule of thumb is in the metric world.]
Cars have gotten more complicated and more computer-controlled. Now there are some additional safety methods; for example, since the AC system needs an electric fan to cool off the condenser, if the fan doesn’t work, it won’t let you have AC. Or if it does, the pressure rises fast, I’ve seen that before. In fact, in training we learned that if the high side pressure goes over 300psi and is still climbing, run; things are about to get interesting.
I was also blessed early in my automotive career to have a real head-scratcher. Late-model Tahoe, customer complained that the AC didn’t work. It didn’t, but not only that, the truck barely idled. Normal idle for those is between 600 and 700 RPM, this thing sometimes dropped below 200.
Turns out that this truck was smart, and it knew that the additional load from the AC compressor would probably stall the engine, so it didn’t let you have it.
We also had Impalas we did pre-delivery inspections on, and in the winter it was hard to make sure the AC worked, since the car reasoned (quite logically) that if it was 20F (-7C), the AC system couldn’t cool the vehicle any more, so there was no point in putting an extra load on the engine, thereby increasing fuel consumption and emissions.
So it’s always a good idea when diagnosing an AC system to make sure that AC compressor operation is allowed, lest one spend far too much time down the wrong diagnostic path.
Last week, we had a fairly late-model F150 in the shop for AC inoperative. Boss hooked up the AC machine and recovered and recharged (which wouldn’t have been my first step, but never mind). I wandered over after he finished and the AC still wasn’t working; he had the scan tool out and was looking at engine data. It wasn’t as good as I would have liked, but I could see a PID saying that AC was allowed. And when you pushed the button on the control head, both the light on the button lit up, and the A/C on the display also lit up.
He pulled the truck out and later in the day, it fell to me to diagnose it. I didn’t hook up the pressure gauges, presuming that he’d correctly charged it, instead I put in the scan tool and checked through the engine PIDs again. One I didn’t note right away was the ACCS switch, which will be important later. That stands for AC Cycling Switch, that’s the low-pressure cutout switch I mentioned before.
Once I got my initial data off the thing, I went to Identifix and with some quick keyword searching, I’d found a pattern failure: the ACCS switch. Scan tool data was less helpful than it should have been, we’re using an aftermarket scan tool which doesn’t always display things the same way the factory one would. I think that a Ford tool said ‘yes’ or ‘no,’ whereas the Snap-On said ‘on’ or ‘off.’
The switch was easy to access and unplug, which if it defaulted to ‘closed’ (which I think it does) should have changed the state on the scan tool, but it didn’t.
Just the same, I jumpered it to see if that would get the AC going, and it didn’t. I checked the supply voltage, which was good, and I checked the continuity to the PCM (who sees the output of that switch), and it was also good.
So assuming I’ve done all my tests correctly, the only component who could have failed was the PCM. It doesn’t see 12 volts from that switch, even though that switch is sending it 12 volts. But I don’t like that theory. Most of the failed PCMs I’ve seen, it’s the high-current stuff that goes bad. Injector drivers melt, coil drivers melt, capacitors explode, but what are the chances that a simple circuit that only detects if a switch is open or closed would fail? Like, it’s not impossible, but I’m not going to suggest the thing needs a six-hundred dollar PCM on a guess. I want to know more, so back to Identifix I went, to check wiring diagrams and re-read how this AC system operates.
No AC clutch engagement with no power to the clutch coil. If the PCM sees an AC request and the ACCS state remains open....
That’s paraphrased, but notice the beginning of the second sentence: ‘If the PCM sees an AC request.’ Maybe the switch state isn’t changing on the data list because the PCM doesn’t see an AC request. That’s not how it would be if I’d programmed the vehicle, but that might be how Ford did it.
So how does the PCM see an AC request?
Back to the computer! Time for a computer data lines diagram! (i.e., a network diagram.)
This truck has . . . I don’t remember Ford’s current acronym for it, probably DATC or DEATC: Dual (Electronic) Automatic Temperature Control, which is its own computer that controls various blend doors under the dash to control where the airflow goes and what the temperature is. On this particular truck, it also controls heated seats and heated mirrors, and all of that stuff is hardwired to it; it doesn’t have to communicate to anybody to do any of those things. But it does have to talk to the PCM to get the AC compressor . . . can it?
One thing I noted from the data lines diagram is that the DATC is on a different network than the PCM. I won’t rehash the network stuff I’ve talked about before, but in a nutshell the DATC is on a low-speed network, and the PCM is on a high-speed bus. Somebody’s got to translate messages between the two.
To further support my hypothesis, I put the scan tool back in the truck and did a module scan. I got codes for the low-speed network being down, and I could not communicate with any module on the low-speed network.
Now we’ve got something we can work with. The DATC appears to be fully-functional, and the PCM likely is as well, it’s just not ever seeing an AC request. No request equals no AC.
I’ll be fully open with y’all, I still don’t know exactly what’s wrong with this truck, but I do know that the signals from the DATC aren’t making to the PCM and in fact no signals on that network are making it off that network. Cars that have multiple networks typically have what’s called a Gateway Module, that’s the one that can translate across networks. It’s usually not a standalone, it’s usually built into something else, ideally something that would have reason to want to be on multiple networks anyway. For example, some late-model Fords have gateway functionality built into the Sync/FCIM system, since that has to be able to talk to multiple vehicle systems; GM had the same idea with the Body Control Module. This is an older truck with no Sync and a more primitive network with the majority of the body functions just carried out by their dedicated module and only rarely being communicated to someone off-network. [In fact, off the top of my head, I can only think of one function that needs to go onto the high-speed bus, and that’s AC operation.]
So they picked the most logical module to do the job: the Instrument Panel Cluster.
Since I never finished diagnosis on that truck before getting pulled off for something else, I don’t know for actual fact if it’s the cluster that’s bad, or if the purple network wire is compromised between the DATC and the IPC, but I do know that on Ford trucks of this era, the IPC has a lot more functionality than you’d think—a damaged IPC might not allow the radio to power up, for example. But, sometime next week I’ll get to put a new IPC in this truck and then we’ll find out if it works, or if it turns into a disaster.
Stay tuned for further updates!
i do AC hear at my garage and i feel your pain.
most are vary easy but dang some of them just suck.
People don't appreciate that mechanics are not only diagnosing a computer, they're diagnosing a network made up of totally different computers, changed every year, connecting wildly different things, and frequently with pack rats gnawing on the wires.
I love reading these because they are fascinating and always have ponies.
while i dont actually work in the field i did actually go to (and graduate from) school for hvac. and yeah that just sounds like all kinds of no fun. best of luck to you
I love that I can click on my feed hoping for some cute horsewords, get an article on air-conditioning instead, and not be disappointed at all!
I don't really see engine driven A/C round my parts often nowadays. With a large proportion of the local car population being hybrid or fully electric, and the local climate being constantly hot year round, I guess people here just want A/C that they can turn on without having to start the car.
I've got a VW that's one of them new-fangled always-on PWM controlled compressors. AC's not working. First thing I did was evac and recharge. Resting pressure seemed too high, like 160 or something. Thought it had air. It didn't. Put it on the scanner, the PCM saw AC request, and even showed the output current to the compressor control solenoid (in both actual and specified, which was nice). And sure enough it appeared to work, from the data, anyway. The climate control module actually had a code for "lower pressure limit not reached" - which I think means it expected the compressor to take the low side down to a specified minimum pressure. Which makes sense. It's obviously not moving the pressure at all, you can watch the pressure sensor data, and it matches the manifold gauges. Thing just does nothing. Funny enough, right after I charged it, it worked for a brief moment.
Anyway, that was saturday night, I'll continue monday.
If there's a giant red button, the giant red button must be pressed.
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I try and minimise differences in the stuff I work on, and that's equipment and products that are designed to allow as much commonality as possible.
What mechanics have to deal with - ugh, stuff of nightmares.
Interesting! Thanks, as usual. :)
And good luck!
Not exactly related to the topic at hoof but
The first image in this post reminds me of a really cool documentary I saw on YouTube some years ago(before it was removed) where a group of 6 engineers from a wide variety of backgrounds and skillsets got together and recreated parts of the lost liner Titanic from her 16-ton forward bow anchor to a steam-powered kitchen.
Well, if that last picture (gif) is in any accurate, then I'd highly suggest to stop pouring coffee into the fuel tank.
Speaking of automotive A/C, know anything about R-420a, particularly in R-12 systems?
(In the past I'd kind of looked at R406a, but apparently its blend contains R-22, which is also being phased out, so... Probably not a great pick.)
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Most of it’s decent work, but there are the ones where it’s just stupid for one reason or another.
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Not only pack rats (or other rodents), but other environmental conditions, including customer handiwork. And every car is using a different OS. Sometimes even the factory tools won’t talk to a specific car, which adds to the fun.
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Thank you!
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It’s great fun, let me tell you. At least most automotive systems are fairly simple overall, which is nice.
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Thank you!
I do what I can to make my thinly-disguised complaining about work be entertaining and full of cute pony pictures.
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Huh, that’s interesting, if you don’t mind me asking, where do you live?
I didn’t bring up hybrid or full-electric air conditioning systems because they’re a whole different beast in several ways--I know that some have full-electric compressors, while some have a compressor that can be belt- or electric-driven (mostly older hybrids). We don’t really work on very many hybrids in our shop, and we don’t have the AC equipment to properly service one nor do I think we could justify buying it.
Heck, we can’t even do 1234yf, although I have to imagine in a few years we’ll buy a machine for that.
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That’s something I haven’t seen yet.
Without any other information, I’d support your theory that the ‘lower pressure limit’ is what it’s expecting on the low side when things are working like they ought to. Is it a variable displacement compressor? Maybe the swash plate’s stuck or something. I am curious about the resting pressure, though, I’m assuming that’s a reading with gauges and not one from the scan tool? Could there be a huge restriction in the system so all the freon you put in got trapped between the high and low side? I can’t really think of a way that could happen, though. Unless the customer put some kind of magic fix-it in the AC system.
Enquiring minds want to know, did you make any progress?
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Yes
To be fair, the automakers do this for an extent . . . on their own cars. Working across multiple makes, though, I’ve got to be conversant in what Ford calls it or GM or Chrysler or Honda or Toyota or Volkswagen or Kia. From experience, I’m probably best at GM and second-best at Ford, since I’ve worked on enough to kind of get in the head of designers.
Like, just today I was diagnosing a power supply issue to an accelerator pedal position sensor, and the repair instructions said things like “if ETCVREF...” which I took to mean “Electronic Throttle Control V-Ref” because that’s how Ford does things. Heck, I should have guessed sooner what the ACCS was, but I wasn’t fully in Ford mode when I started looking at it.
It can be, no question.
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Shame that was taken down, it would be interesting to see. I’ve seen other similar videos where people try to recreate things and there’s a lot of learning in the process. I just today saw a Tom Scott video where a British space museum recreated a theorized British space suit using techniques and materials that would have been available in the 30s. It’s basically what you’d get if you had someone who was familiar with hard-hat diving suits make a futuristic-looking one for space:
spacecentre.co.uk/wp-content/uploads/2019/07/BIS-suit-2-e1562079162571.jpg
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Never, cars run better when they’re caffeinated.
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Nope, never even heard of it.
I’m assuming you’re trying to retrofit something and want the closest match to R-12 or want to keep it as close to original as possible? Because unless it’s really weird you could convert to R-134, although with some loss in performance. (And depending on what it is, some parts could be replaced with more modern components.)
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That looks like a suit of armor I might have drawn in middle school XD.
I'm fairly certain that you can find it elsewhere online, just the whole videos were removed on account of copyrights and all that jazz.
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Singapore. We'll apparently be phasing out ICE cars in a couple years or so.
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Depending on if it is available or not due to your local rules, you could try HR-12 as a drop in for R-12. I have been using HR-12 as a quick fix for R-12 and R134a systems for a while and it seems to work well. Pretty much the same or slightly better performance as R-12 and markedly more efficient than R134a. If I remember right, it is a blend of R600a and R290 (environmentally natural gasses which we use for other uses all the time) and you only use about a third of the charge weight as you would with R134a. Brand name over here is usually HyChill. Low environmental impact gas (low GWR for those who have concerns).
I have heard comments on flammability but keep in mind, R134a and R-12 while not flammable themselves, once mixed with the system lubricant the blend is flammable and they produce high or very high toxicity results while HR-12 is deemed low toxicity when burnt.
5524409 Variable displacement, I guess you could call it that. A lot of newer cars are like that. Basically, there is no clutch, the compressor is always engaged. And there's a pwm-controlled solenoid on the side of it, that'll determine the duty cycle of the compressor. At 0% (I assume) the compressor is just bypassed by the solenoid, so it does nothing. Incidentally, you're not supposed to run the engine with the system empty or under vacuum.
Also, the reading was by gauges and through the scan tool. Which is good, because since the two measurements agree, that means the pressure sensor is working properly. I doubt there's a restriction, I feel like the compressor would do something if that were the case. I'm thinking the system might just be that damn small, so the charge rests at a high pressure. Not sure.
Anyway, I'll have to get back to you. Spent all day drilling exhaust manifold bolts.
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I know, right? It’s amazing.
Gotcha, that makes sense. It’s disappointing, but it makes sense.
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Huh, interesting. Here where I am (rural Michigan) there aren’t all that many hybrids or full electrics around yet, that might change with Ford’s new F150 Lightning.
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Huh, that’s not a system I’m familiar with, although I’d believe it’s the new thing. Just haven’t run into one yet that needs AC work, I guess. Lots of our customers have trucks which so far have had more traditional systems, the only other late-model AC system I can remember getting into somewhat recently was on a little Ford Fiesta or Focus where it’s on the very bottom of the engine, owner scraped the compressor off on something.
Is it a 1234YF car? We don’t have the stuff to service those.
Yeah, I figured you’d compared readings, but had to ask, y’know? Maybe it is a new thing . . . I caught some of the tail end of R12, mostly did retrofits on those, and then it’s been basically the same R134 systems on what I’ve been working on anyway, and we currently have no interest in doing hybrids or 1234YF, although that might change as more of them get on the road.
I’ve been lucky on that recently, I did manifolds on two Rams and a Jeep with a 3.8 and I got all but one of them out with a stud remover. Last one was flush, manager tried to drill it, broke a Torx socket in it, then welded a nut to it and it came right out.
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It's a 2006 vw passat. So no. Admittedly, it's fairly early for that type of thing. It's much more common on 2010+. Maybe not so common on trucks, which tend to use tried-and-true tech, but increasingly common on cars. Surprised you haven't seen it yet. More likely that you simply haven't noticed. They're basically the same in every other respect, except that instead of a magnetic clutch, you have a solenoid that's PWM'd.
A: it's bullshit that hybrids use different oil and B: it's bullshit that there's like zero aftermarket support for hybrid A/C's. Legit the one time I needed to do a hybrid, I had to make like 10 phone calls to find a bottle of that special bullshit PAG oil. I'm seriously doubting that it's even anything special, tbh. Probably a repeat of the 7/11s CHF mineral oil bullshit. They're all the same shit but everyone and their dog says otherwise...
Lucky. I had iron heads, didn't want to risk welding to the head lol. Anyhow we sold that VW as is (it was ours) not sure if I'll see it back... but I probably will, lol.
Fuckin' A. You know what happened? That VW sat in our shop for well over a year, needing a timing belt - not so simple on those, since it's a belt, plus a chain to tie the two camshafts together, plus another chain for the balance shaft and oil pump. (2.0L turbo.) After all that shit, it kept coming up with a camshaft over-advanced code. I changed the camshaft phaser thingy on it (though really, I think it was because the cover was missing a dial pin, as the cover is the oil feed for the system). And it worked. But legit, the day after we finally sold that POS, our Mexican junk man comes by with another one of the same fucking car with the same fucking engine, with the same fucking timing chain rattle as the first one, and asks me if I want to buy it (oh but the guy he was selling it for wanted to keep the catalytic converter for some dumbass reason - as if it was worth something
)... yeah, I told him no thanks.
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Yeah, it’s probably something I’ve seen before and never had to diagnose. As I recall, most of our late-model AC services have been repairing busted condensers and recharging systems that the customers don’t want leak-checked, and a few compressor failures—like on that one Ford where it’s low enough on the engine it’s got its own skid plate. Fiestas, I think. Turns out that skid plate’s pretty robust but not indestructible.
What I heard from trainers back in the day was that the challenge with hybrid AC systems is that if you were using recycled freon there could be some incompatible oil or metal in it, and if the hybrid has an electric compressor, it could short it out.
We might get to find out soon; my manager decided to use our machine to recharge a Prius. If it comes back in with a failed compressor, I’ll let you know.
I feel like the welding trick works on iron heads, too, but I legit don’t know. I really suck at welding and let my manager do it.
Yeah, that’s one of those cars you learn from and want nothing to do with ever again.
I spent most of the last week putting timing chains on a GM 3.6 in an Acadia or whatever. Which isn’t that challenging job, BUT. . . .
So some time back, can’t remember if I ever blogged about it, we did chains on a Ford 3.5, pretty much the same concept as this one. That Ford also got cam phasers and solenoids. Lot of crud in them, metal glitter, you know the drill. Not well maintained, and in fact we’d been servicing this (and other vehicles) for that customer since it was new, so we know how well he takes care of his stuff.
About three grand later, it runs, but it keeps setting cam codes. Pull the solenoids out, they’ve got metal in them again. There was so much in the oil passages and galleys that there was no way we were ever going to get the phasers to work reliably (I mean, barring tearing it all down and cleaning everything) and the best bet was a reman.
Ultimately, my boss installed a used engine for the guy for free and I learned what I really already knew on some of that stuff, if it’s bad enough the part that broke won’t be the only problem.
So this Acadia, out of time. Told it won’t start, and the battery’s dead, so I push it in. Start tearing it down, and when I get the intake off, there’s so much carbon on the valves, I should have taken a picture. GM’s got a TSB for GDI valves sticking due to carbon, and all the examples in their picture looked way better than this thing did. Even with the spark plugs out, took a breaker bar to rotate the engine, and we never did get it close to in time with the chains on. I also found out that the thing stopped running and the first thing the customer did was check the oil, and didn’t find any.
Took about six hours to set the chains because my boss didn’t want to do it ‘by the book,’ claiming his method was faster, and maybe sometimes it is, I dunno. Problem was that one uses plates to hold the cams in position, but the lock pins in the phazers didn’t work, so it took two hands to hold the timing gears in place with the colored link, a second person to watch the idler gear, and a third person to pull the grenade pin on the tensioner.
It took forever to actually start, and when it did, it predictably ran horribly. No timing codes, though. After running two cans of intake cleaner through it and running it for hours with transmission fluid in place of the oil, it eventually got to only having a dead miss on cyl 1.
Shoulda just put an engine in it.
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So wait, the chain jumped, but didn't bend the valves? I'm surprised (well, not really, with your manager lol) that you guys didn't sell him a head job or something to clean the valves before gambling that the motor would start like that. Shit, the engine being almost locked up like that - in my limited experience - even if they do run, it won't be for long.
No kidding.
Currently I have an 09 Audi A4, 2.0L Turbo (newer and different from the Passat I was complaining about). This one belongs to the owner of an oil change shop, we're good friends with him, and do a lot of jobs for him. Ok, it's his personal car, mind you. 60k miles on the clock, and it's already had the turbo replaced. It's not running, and it only took me 2 seconds of cranking the engine to tell the timing chain had jumped. You can actually hear the chain dislodging. I drain the oil, 4 quarts came out - I think it's full (no dipstick) - and it's black mud. This guy can have as many free oil changes as he wants.
Admittedly, he was complaining of leaking or burning oil (the intake valves are caked in carbon) so there's a possibility he's been only adding oil to it constantly, and doesn't understand that only a portion of the hydrocarbons that comprise the oil leak out, so after some time, the 'oil' remaining in the engine isn't really 'oil' any more. Interestingly, the inside of the motor looks sparkling and clean, and still new. You know, that glistening gray color, not even golden brown yet? Anyhow, the main chain tensioner looks to be about at the end of its travel. Chain looks stretched. There are three, btw. Main one, oil pump, balance shaft(s?). And a set of gears running off of one of those, to a shaft that comes out of the side of the block to turn a tiny baby toothed belt to run the water pump.
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I’ll be honest, I have found that many AC systems are more robust than the service instructions would lead you to believe. Like, those GM trucks with the AC compressor on the bottom (5.3s and their kin)? Got one where I took the leaking line off the compressor and it drained out a bunch of water. That didn’t kill the compressor.
And we’re often sloppy about adding oil, or the right kind of oil if it’s hard to find in service instructions (seriously, why do they make it so hard to find out what weight of PAG oil you’re supposed to use?).
Your prediction was accurate! It made it through some of the weekend before it quit running, and we pushed it back in the shop and I started tearing it down, and now one of the intake valves for #3 is embedded in the piston.
Now it’s getting a new engine. Which it should have got the first time around.
Pfft, my experience with mechanics is that they either have very well-maintained cars, or they can’t be bothered. Although I change my oil at least. . . .
Also I hate those no-dipstick cars. Why?
That sounds like a lot of fun . . .
We don’t do many German or British cars, for which I am very thankful. They’re their own special kind of animal. Like not that long ago I had to do some diagnostics on a Mercedes and just figuring out how the code structure worked and then what I needed to put into Identifix to get instructions to diagnose the failure, or the annoyance of the service information referring to them by body model which isn’t the same as the model number stuck on the back in chrome . . . grr.
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NicE!
Dumb engineers? They have nothing to do, and they don't wanna get fired, so they say "hey look, we can save an ounce of weight and a penny on each car by omitting the dipstick!" It did at least have a tube, but it seems like it didn't have a stop at the bottom to prevent a universal dipstick from just going all the way into the pan. Incidentally, when I called the German-aftermarket-parts-store, the guy already had a list ready of everything I'd need for the job. Tells you just how many of those motors have that problem
Actually, he told me he makes a living selling that particular set of parts, and that he'd quit if people stopped buying them lol. Also, that one didn't bend the valves. Surprised me, tbh. (Btw, you should see the ridiculous VVT setup they have...)
Our engine machinist stopped by and looked at the top of the pistons and said the rings were leaking oil. So I pulled the block out on Saturday. Not what most mechanics would call 'easy,' but not what I'd call 'hard.' Lots of little things, though. The rings all look fine to me, though to be fair, they're all very very thin rings. Not like good old fashioned piston rings. Perhaps that's why they have problems.
lol oh yeah, I hate that. And you get the German car snobs that only refer to their own car by the body model designation, as if anybody knows that shit. I wouldn't mind it so much if they'd just WRITE THE DAMN NUMBER some place. Instead, it's basically the equivalent to a secret code. Using make-specific VIN decoders helps.
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Now after a week-long struggle, it’s got a new engine and left the shop today and I hope I don’t see it again for a long time.
We get that sometimes. “Oh, you’re ordering these things? You’ll want this, too.” Funnily enough, one of our guys broke a bolt off in a Toyota motor mount when doing a timing chain and I ordered new bolts but not the mount. Parts guy assumed I wanted it, and I said we got the bolt out.
There was a pause. “How?”
Henry Ford allegedly said that if he had a lock on the repair part market, he’d give away cars.
It can’t be worse than what Nissan came up with, can it?
I wouldn’t want to do it, I was never any good at heavy work. I’m not fast, and I forget stuff if I get pulled off the job and then go back to it later. I’ve been getting better at taking lots of pictures to keep track of where things should go during reassembly, and that helps. Not to mention that Firestone always undercharged for heavy work, and when I was flat-rate that really mattered.
I’ve never heard anybody doing that, which is just as well. I have considered, since there are some GM vehicles which have the RPO code proudly displayed in the model designation or on their flanks (Z06, Z71, etc.) calling my GM vehicle by some randomly-selected RPO code number. “Oh yeah, I’ve got an Astro FE9.”*
They probably want you to buy the Mercedes Secret Decoder Ring (TM).
I just ran into that with an Odyssey, there were two different 3.5L engines for the model year with different 5-digit codes. Still don’t know which one it had, luckily the timing belt went on the same for either. But when we had to order a crank sensor for it, it could have been either, so we had to order both and then send back the one that was wrong.
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*to save you the trouble of looking it up, FE9 is ‘Federal Emissions Standards.’