Automotive Air Conditioning Information Forum (Archives)

GaryRidgway on Sat August 03, 2013 3:52 AM

Year: 00
Make: dodge
Model: durango
Engine Size: 5.9
Refrigerant Type: 134
Ambient Temp: 80
Pressure Low: 30-40
Pressure High: 200
Country of Origin: United States

I'm trying to fix my crappy Durango. Every waterhead in the world has had an opinion as to what the problem is and I have hung quite a few parts on it, but the performance of the system is blah. Original problem was that AC was not getting cold enough, some dummy decided it would be a good idea to add some refrigerant. This did absolutely nothing to improve the problem. A year later the AC completely quit working. Had the same pressure on high side and low side, put a new compressor in and now we have unacceptable cool (not cold air) and pressures seem to be OK(cant remember exact figures). At a loss as to why it was still not very cold replaced both expansion valves because thats what some of my waterhead friends told me to do. I'm confused because pressures seem fine but I go ahead and replace both front and rear expansion valves. Air works exactly the same after replacement of expansion valves except now it will leak out every 2 days. The fine retail establishment of autozone sold me a expansion valve that came with incorrect o-rings and I knew when i put that valve on they didn't seem to fit right. I put a couple ounces of oil in with uv dye to try to locate the leak, I found nothing. Remembering that I had trouble with the o-rings on the back expansion valve I took it apart and went and bought a complete oring kit for the vehicle. I found the proper orings in the kit and put them on the rear expansion valve and they seemed to fit correctly. Anyways I vac the system down for 1 hour while I put the trim pieces back over the rear ac evaporator housing. I charged the system up and drove it around for awhile. The vent temp in the back ac vents felt like a car with crappy ac but was acceptable, the front was close to being acceptable but an unimpressive 65 on an 80 degree day. I got good pressures it seems, Can't be airflow over condensor because in my mind performance is still lacking at highway speeds, blower motors are both moving an acceptable amount of air also. I thought for sure a blend door must be screwed up on the front so instead of taking the dash apart to check I just bypassed the heater core. Now on my 80 degree day I am having vent temps of 60 degrees. Bypassing heater core seems to have knocked me into the ac works but is nothing to call home about range. Do you guys see anything I am missing? One thing I did notice is that the condenser on the front of this thing is comical in thickness and size, almost small like a r12 condenser would be. Getting a 5 degree drop from bypassing the heater core was quite the improvement but nowhere near what i think it should be. Any Ideas would be appreciated. I've tried undercharging and overcharging just a hair to see what would happen and nothing significant. (I know thats bad for compressor to overcharge too much)

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If you think your boss is stupid, remember: you wouldn't have a job if he was any smarter.

mk378 on Sat August 03, 2013 8:40 AM

Did your original compressor had an internal failure, where it would turn but not pump? If that's the case something came apart inside, which will often clog the condenser with bits of metal from the compressor. Condenser should have been replaced.

Another way to get persistently lousy performance after a compressor replacement is to put in way too much oil. New compressors typically come full of oil because they don't want warranty failures from lack of oil.

Edited: Sat August 03, 2013 at 8:42 AM by mk378

webbch on Sat August 03, 2013 12:02 PM

1) When the compressor was replaced, what, if anything was flushed? This will allow us to evaluate how much oil should have been added, as well as to the liklihood of residual junk in the lines and, most worrisome, the condenser.
2) When the compressor was replaced, what other components, if any, were replaced? At a minimum, the drier should've been replaced
3) When the compressor was replaced: how much oil was added?
4) When you replaced the expansiion valve, you "added a couple of ounces of oil with uv dye...." Adding 2 oz of oil during replaced of TXV? Was there really much oil that came out when you removed the TXV? I'm not familiar with the locations of the TXV on that vehicle....did a bunch drain out when the TXV was removed? If not, no reason to add any oil IMO, and 2 oz is WAY too much.
5) Please confirm that the vacuum pump you're using is NOT the kind that hooks up to your air compressor.

When I last replaced the compressor on my truck, the new one came with an oil spec that read as if it was for the compressor only, but was really the total system oil capacity. It's an easy mistake to make if you don't have a feel for how much the various components OUGHT to take. I think mk378 may have hit on the potential of having too much oil, which will cause poor cooling. If you are unsure of how much oil is in the system, the right thing to do is flush everything out and start over.