Engine Size: 2.7L
Refrigerant Type: R-134A
Country of Origin: United States
Just joined this forum after lurking it for awhile and can see that there are extremely talented individuals here with regard to automotive AC systems!
While I am an experienced mechanic, I dont have much experience at all with auto AC systems and would like to gain some knowledge as I am currently dealing with an issue with my 'better-half's' car.
She complained that her AC was not working and had not worked for quite some time. There was air flow from the ducts but not cold at all. I looked at the compressor and found that the clutch never engaged. I checked voltage at the wiring harness and found that it was getting voltage in cycles. I also verified the ground, so I figured the compressor/clutch was toast. One other diagnosis I made was that there was ZERO pressure of refrigerant in the system. I went ahead and purchased a new compressor and prepared for the install.
This is where my experience with auto AC systems began to get interesting! LOL!
About 2 months ago, I removed old compressor, measured the oil contained within and replaced it with fresh PAG100 in the new compressor (according to instruction that came with new compressor). I also verified that the old compressor was indeed TOAST, locked down tight. I lubed new seals and reinstalled lines to the compressor. I then employed my handy dandy WalMart refrigerant top off kit and charged the system with a can and a half of fresh R-134A. I then tried to operate the system and found that the new clutch/compressor cycled normally, but still no cool air in the cabin?? Finally, after about 10 min, there appeared to be a 'fog' accumulating in the cabin of the car and still no cool air.
Stumped as to why my repair didnt appear to work, I turned the system off and instructed my gal NOT to use the system until I could troubleshoot it. I began researching auto AC systems and the more I read, the more my head hurt concerning how I had proceeded with this repair! ...and my lady STILL has no AC in her Tib.
Since then, I have purchased 2 manuals (Haynes Automotive Heating and Air Conditioning, and Modern Automotive HVAC Systems, Volume 1 by MACS). I have read and reread both manuals in an effort to gain an understanding of auto AC. I have purchased a Mastercool Manifold set, a Mastercool leak detection kit (includes Dye and sniffer), a Robinair 3.0CFM vacuum pump and a Mastercool flush gun kit.
I have yet to use any of my new tooling or knowledge on this system as I am having "Which came first, the chicken or the egg" brain-lock. I hate to run the system with dye first as I know that I have introduced air into the system, much less what could be in the system due to the catastrophic failure of the original compressor. I hope what little time I have run the new compressor hasnt caused damage to it as well!!
If this type of problem showed up at your shop, where would you start? How would you proceed?
I appreciate any advice in advance!!
Find the leak would be the first thing to address.
Appreciate the info TRB!
Any idea what wouldve caused the 'fog' in the cabin?? I was thinking massive leak in the evap leaking refrigerant into the cabin?? I may be way off, but couldnt think of anything else that wouldve caused this??
There is a chance you have a large leak. Refrigerant has no color or smell. So the fog might have been the refrigerant and oil mixture. Again, you need to find and fix the leak before progressing on to further diagnostics.
I'm on it, TRB. I will report my findings ASAP.
Once again, thanks for the help!
First thing I did tonight was assemble the new manifold gauges (with Fittings) and hook it up to the system statically, with the engine off. Readings were:
Low= 125 psi
Next, I started the engine and let it run for about 10 min. (AC ON, full blower). I noticed that the compressor never cycled, ran constant. After 10min:
System performance=Mildly cool air-warm air from the vents
I then read into the troubleshooting section of the manual and saw a common symptom: OVERCHARGE (No surprise since I originally charged with the Wally-World quicky-tool)
I then vented it off to where it eventually stabilized after running for 10min at:
System performance=Air seemed cooler and started noticing a puddle coming out from under the car
I then shut the car down and injected a shot of dye into the low side (purged injector according to directions prior to injection). Took it for a drive and all seems to be operating correctly (although the air is still not very cold obviously). Instructed the lil woman to run the AC sporadically tomorrow to see if I can spotlight the leak tomorrow evening.
So, is it normal that the compressor run constantly and never cycle??
What you need to do after checking for a leak is reclaim the refrigerant and charge to OEM specifications. Obvisuoly you would repair any leak first. You need a proper charge period in the system. No amtter what the readings are. If they are off wiht a proper charge, then find out why! Under or over charging will kill your compressor.
Got it, TRB.
She ran the system today and said it performed MUCH cooler than normal. She probably drives 60 miles round trip to work and back, so hoping that was enough to generate enough dye at the leak-point for me to find and fix. Dont plan on letting her run it anymore until I can get the light on it and see if I can find that leak.
Since the last compressor seized, I was thinking I need to:
1). Evacuate the system once leak is located
2). Repair the leak
3). Flush the condensor/evaporator (assuming they dont get replaced for the leak)
4). Pull vacuum on the system
5). Recharge the system correctly
Sound about right?
Be sure to replace your drier.
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