300M A/C pressures way too high (solution)

Festive. So you had a flooded evaporator and a short-cycling compressor due to the HPCO activation. Yep, that'll drop efficiency right through the floor!

I'm curious what technique you used to do so.

Probably not -- the HPCO kept system pressures from climbing too high. The weakest link is the compressor shaft seal; if it didn't let go (and it sounds as though it didn't) you should be fine.

DS

Sorry, I did not catch - what was an initial cause of the problem? Ok, the dealer overcharged your system, but it was AFTER something happened. Did you find what was wrong?

Regards, Alex

I was reasonably thorough, but not completely anal about it. I disconnected the hoses leading to the expansion valve, blew the lines out with compressed air, then did the same thing with the evaporator and condenser. I then took the lines off the compressor, removed it and hung it upside down for 15-20 minutes to get as much out of there as possible. I replaced the accumulator/receiver/drier since I had no idea what those buffoons put in there...better safe than sorry. Then I added a few ounces of PAG, put everything back together, evacuated the system (it held the vacuum for an hour or two so I knew it didn't have any major leaks) and recharged it with

24oz of 134a. Had I realized just how much of a pain in the ass it is to adjust the A/C belt, I probably would have skipped the compressor step. 8-)

Cheers,

C

Not sure. The initial symptom was that the system was not cooling adequately and when I checked it out there was abnormally high pressure on the low side. I'm thinking that there must have been a blockage somewhere because when I cleaned it out, evacuated it, and recharged the system things worked as expected. This was the first problem I had with the A/C. Historically, it has worked extremely well. Now I know not to let the dealer touch it. That's what I get for being lazy and trusting.

Cheers,

C

I'm with you on it!

Regards, Alex

Yeah. I have an extended warranty and thought the compressor was shot so I figured I'd let someone else deal with the pain in the ass of changing it. Oh well.

C

My Final Dealer Experience (tm) also involved A/C. Several years ago, my wife's 93 Vision TSi finally blew out the evaporator core, as virtually all early first-gen LH cars did. I let the dealer replace it, and over the next year the A/C worked fine, but the compressor grew increasingly loud. Well, it did have 120,000+ miles on it, so I figured it was just a typical crappy Japanese-designed compressor (Nippondenso) getting noisy. It finally seized, and so I replaced it myself. To make sure it hadn't sprayed its guts throughout the system, I disassembled it, and guess what I found? NO OIL. Just a thin film. One of the pistons had seized to its bore and locked up virtually instantly- no aluminum shavings made it further than the valve block, so none got into the system.

One rebuilt Nippondenso, one FULL load of PAG oil, pull a vacuum, put in the recommended charge of R-134a, and its been fine for about the past

80k miles (the car just passed 200,000 miles a few weeks ago).

I *know* there are good mechanics working in dealerships out there. But I think there is huge institutional pressure to cut corners, perform unnecessary work, and NOT perform some critical checks (like verifying the system oil level following a refrigerant leak!!!) in order to stay "profitable" no matter how pissed the customers become.

Chris Mauritz wrote:

At the small brand 'LM' dealership for which I briefly worked as a service writer 12 years ago, the owner made no bones about his strategy: 90% of the revenue for the business came from the service department. Car sales in a smaller operation are often not enough to support the business; you have to generate good service revenue. Hence the accelerated routine service schedules, the blatant ripoffs ($65 to change 4 sparkplugs, for example, at a time when labor was ~$40/hour) the foisting of the hard-to-diagnose or reproduce problems back onto the customer ('Couldn't verify problem'), etc.

--Geoff

Flat rate isn't so bad when you're doing straight forward repair work, it's when heavy diagnostics are needed that the system falls short. That and all the special policy labor ops which are nothing more than some junior VP dumping his f*&k-up on the backs of the mechanics.

Hell, I remember the final brake recall GM had on the 1980 "X" bodies, install new shoes, cut the drums, replace the parking brake cables from the pedal back, adjust everything 'just so.'

Paid 5.7 hours, took 1.5. But back then, we had to walk 20 miles thru 4 foot snow drifts, up hill both ways to the training center...

It was real strange - I new nothing about the auto industry at the time, and I was in my early 20's. I called information, and somehow (don't remember how I did it) I got thru to an actual brake engineer somewhere within the bowels of GM. The guy actually told me the history of how the problem got created, and told me that the real fix would be to put on rear shoes from an auto tranny car - and he ended up by saying that if I ever said he gave me the information, that he would deny it - this was very early on with the problem before it was known by the public.

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

Yup, we knew at the dealership level that using the part number for the automatic equiped cars yielded improvements, except that we couldn't do it due to liability reasons.

I believe that the 1980 GM X chassis still holds the record for the vehicle with the most recalls ever issued.

And as cars get more complicated, MORE heavy diagnostic time is needed. The system needs to adapt with the times, don't you think? .

Careful what you compare it to, Neil - some people here might think that's a good thing.

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

That was me. :-) And I was also thinking it is a way for the manufacturer to make the system self-documenting to the point where they don't have to go to the bother of printing up and distributing manuals.

These days web servers can easily fit into an engine computer. Take a look at this one

the chip that runs it is smaller than anethernet connector.

Ted

My 99 Intrepid (LH, same a/c system) has had short cycles ( and a loud hiss! when the compressor engages since day 1.) Dealer said there was nothing wrong with the loud hiss, nor the frequent (every 14 seconds or so) engaging of the compressor.

I have always wondered if it was cycling on the high pressure cut-off switch and asked the dealer about that. They simply said that there wasn't a spec. for cycle time intervals. I can't find one either in the svc manual.

Meanwhile, the a/c does get cold, but those constant hisses (loudness depends on engine RPM) are annoying since they occur every 14 seconds. More recently I have also noticed more of a rumbling sound (like you would hear from a muffler that is starting to go south) that also varies in loudness with engine RPM. Anybody have similar experiences?

Eh?

What data does the dealership service department get that you cannot obtain from purchasing the factory service manual set, and/or alldata, along with the appropriate diagnostic tools?

Granted, a DRB scanner from Chrysler is about $5K new, but aftermarket ones exist that do virtually everything that the factory one does.

Dealership service departments live off warranty work, done both with factory warranty and under extended warranty. And the new warranties appear to be longer, so this is just going to have the effect of driving more people into the dealership service department first. (in hopes that the problem is covered under warranty)

Making it easier for the car to tell the owner what the problem is, isn't going to do anything to bugger up the current system. For crying out loud, the majority of people actually PAY someone labor to do oil changes! If the general public is so mechanically inept that they cannot even do that, then how is giving the owner a better idea of what is wrong going to decrease service work for the dealership?

Consider this too. While I've never worked in a dealership service department I get the feeling that most dealership service department managers would hire all minimum-wage, entry-level, inexperienced parts-changers if they thought they could get away with it. Certainly it seems like most dealership service departments have a large percentage of people like this and a small percentage of mechanics that really know their ass from a hole in the ground. If anyone is yelling to the automakers to make their cars easier to diagnose, it's the dealerships, simply so they can hire less-experienced, cheaper mechanics.

Ted

That sure sounds like an overcharged system to me. You might want to find someone with the appropriate guage set and see what your low and high pressures are like to be sure. As soon as I recharged my system to the correct specs, the short cycling stopped and the compressor became noticibly quieter.

Cheers,

C