Mechanics

AIR CONDITIONING SYSTEM

2006 Dodge Caravan • 125,000 miles

Car went to dealer with leak in AC and noisy compressor. Dealer changed out evaporator and compressor. Picked up car and no AC. Took back. Said drier had disintegrated and plugged lines. Need to replace two lines and drier.

Did some research as I have access to Ford service documents and they say to change out drier whenever compressor is changed out. Chrysler dealer said he never heard of such thing. Most of my research says that if compressor is changed drier should be changed as desiccant rapidly takes on moisture as well as filter will allow dirt into system.

Two questions: First is it industry standard to change out drier when compressor is changed? Secondly, if they replace lines, drier and flush system, will all be well or will I have problems with moisture and/or contaminants in the future.

Thanks

JU
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Jerry9n
April 29, 2013.



Yes, it's standard procedure to replace the receiver / drier anytime the system is opened, but many mechanics try to reduce your cost by not doing that. The result is you think they did poor quality work, and you're angry with them if your vehicle is the one out of a hundred that develops another problem. To avoid that some mechanics have to avoid being conscientious to your wallet and they just replace everything that might cause a problem later.

If the drier disintegrated as they said, it did that a while ago and the problem would have been there as soon as they replaced the compressor. The material would plug the "H-valve" with its tiny orifice, not the hoses.

You also have to look at why the compressor was replaced. The electric clutch causes a lot more trouble than the compressor itself. That would not require a new drier. If the compressor was coming apart inside there could be metal chips circulating in the system. Those would be trapped in the filter in the drier and could plug it. The cooling occurs at the point of a controlled and variable restriction which is that H-valve, but if there's some other restriction in the system, cooling will take place there. If the filter in the drier is plugged you will find frost forming on the hose leaving it.

The main reason the drier is replaced is it has a desiccant that removes moisture from the refrigerant. It can hold about ten droplets of water. One droplet is way too much in the system. It will freeze at the orifice where it gets real cold. That will stop the flow of refrigerant until it warms up, melts, and circulates back around again. That will cause intermittent cooling. We get that moisture out by pumping the system into a huge vacuum for a half hour before we put the refrigerant in. Under vacuum water boils at 77 degrees and can be sucked out as a vapor.

Given the recent repairs, I'm more inclined to believe a connection is leaking and the new refrigerant leaked out while the van was sitting in the parking lot waiting to be picked up. Pressure tests will verify that. Mechanics have electronic leak detectors to find those leaks but they don't always show up right away. A leak can be so small that natural air flow in the building blows the leaking refrigerant away, and the leak won't show up.

I wouldn't agree to having any more parts replaced until the system is properly diagnosed and the pressures are tested. If the system is still under full pressure, be sure the compressor is running. You'll see the clutch cycle on and off once or twice per minute. (Some run continuously). If the compressor doesn't cycle on or stay on, the system is low on charge and a safety cut-out switch is preventing it from running. That would point to a leak. The problem with leaks is there are often more than one but a lot of mechanics stop looking after they find the first one. Condensers in front of the radiator often corrode through, and hoses commonly leak next to the metal crimped-on fittings. The clue is you will see oil residue around the leak.


Caradiodoc
Apr 29, 2013.
I know in the aftermarket the compressor rebuilders will not warranty the compressor if the drier, oriface tube(if used), any muffler lines, and possible condensor, are not replace to go along with flushing what is left. When the systems run low from leakage the the oil in the system has a tendancy to collect and stay, poosibly starving compressor causing it to destroy itself. If the system is not completely clean the particles and stuff spewed out from the previous compressor can contaminate the new compressor and possibly ruin the new one. Most a/c systems can tollerate a small varience in refrigerant charge but it doesn't take much to render them ineffective. Most of the systems have pressure switches in them to prevent activation if system is to low to engage. You never stated if htis was a warranty repair or not? What type of condensor is installed? Evap usually a bummer to replace, was that the leak? Wasn't the system leak checked and tested before you picked it up? If so what went wrong? Sooorryy for soo many questions but I'm trying to be complete. Have you gotton a customer survey from the dealership yet? I better stop here.


Dugsmobile
Apr 29, 2013.
Update. Not under warranty. Compressor would run but not cycle. They said all refrigerant showed it was on the high side due to plugged lines. Condenser was not replaced. Leak was in evaporator which they determined when they recharged it and dye tested it.

Not much I can do now but go on with repairs. Only question: was the second repair necessitated because dryer wasn't replaced. Most references I find say they should have just replaced it, not a big ticket item.

Thanks for the help.

JU


Tiny
Jerry9n
Apr 29, 2013.
Replacing the receiver / drier used to be standard procedure but it has become a judgement call because they're trying to save you money. A lot of customers complain that they were sold parts they didn't need and in response many mechanics cut corners they probably shouldn't.

I don't believe you need new hoses unless there is something built into them that I'm not aware of. Often two hoses are manufactured as one assembly with an attaching block or some other component included as part of that assembly. The H-valve assembly is what has the orifice that gets plugged most often, but the filter in the receiver / drier can get plugged too. That would be a result of the compressor failure and should have been a part of the first repair. It would not be the result of something the mechanic did wrong.

I should clarify that. He didn't do anything wrong during the repair procedure to cause the new problem. What he did wrong, I assume, was not go far enough, and he left a part on the vehicle that should have also been replaced.

When I worked for a very nice family-owned Chrysler dealership a problem like this was handled by you being charged only for the additional parts and labor that should have been included originally. We would not charge you again to evacuate the system and recharge it.


Caradiodoc
Apr 29, 2013.
I agree that the only choice is to continue. I would, if this were my dealer, replace the compressor again, flush the evap, lines, and the h-block under our warranty. Would charge for the drier and suggest replace the condensor, these are multipass setups which usually cannot be flushed properly as any contaminates only block some of the tubes. Under use with the high pressures and temperatures these contaminates can dislodge and FOD(foreign object damage) the system again. Sounds more expensive and is, but what is peace of mind and longevity worth? You got 7 years from the first system you should get the same or better this time.


Dugsmobile
Apr 30, 2013.