Engine Size: 350
Refrigerant Type: r134
Country of Origin: United States
Everything in the system has been converted to use the r134 freon. The ac seemed to be working fine for a week but then I got a leak in the cold line. I bought a new cooling line and had it replaced . Now it blows cold but after sitting for awhile like in traffic it will blow warm. It will stay blowing warm and only go back to blowing cold when I floor the gas pedal. Then it will blow cold again.
I just picked up the truck from the shop and the guy tells me all is fine pressure readings are fine and it should be working, no leaks. I get in and can tell its been sitting with the ac running because of the big puddle of water under the truck. I get in start it up and it blowing warm again. The shop was closing for the day so I didnt even bother with the shop, I just left. They didnt charge any money for this visit. I get on the main road and floor the gas pedal and it starts blowing cold again.
What to do? If some one could tell me what gauges to buy and if I can maybe fix this myself it would be great. I have spent at least 1500 dollars on this ac system with conversion and all and still at square one it seems. I lost count of how many compressors, accumulators, and switches replaced.
First, you can rent guages from Autozone. When the truck is idling with the AC turnrd on, see if the clutch on the compressor is engaged. The center hub should be turning. Does this vehicle have a wide open throttle switch on the accelerator? It may not be working properly thus removing 12 volts from the clutch. Also, check the cooling fan. You may not be getting enough airflow at idle speed due to a non-efficient cooling fan set up. Tell us what the high side guage reads whie at idle. Then mist the condenser with a water hose and note the pressure. If the high side drops like a rock, you have an airflow problem with the condenser.
I think the compressor is right on top of the engine so you can relatively safely hit the clutch plate with a wooden stick. Do this while the truck is running, A/C switch on, but compressor not engaged and blowing warm air. If tapping the plate makes the compressor pull in right away, the clutch gap is too wide which is an easy fix-- but you will need a special GM clutch plate installer tool. This tool should be available at local parts stores. (although the one commonly found has metric threads for the compressor shaft, your compressor if original may be old enough to have inch threads and you need a different tool.)
Revving the engine makes everything vibrate which is similar to tapping on the plate-- you don't have to hit it hard just help the magnet a little and it will snap down and run cold until the next cycle when again it fails to engage.
If it doesn't seem to be the clutch, the pressure switch on the accumulator also can become intermittent-- tap on it-- realize the base is only plastic though. Also check for loose wires especially on the 2 wire plug for the clutch coil.
Edited: Tue May 26, 2015 at 9:42 PM by mk378
Thanks for the help I adjusted the clutch from .020 to .014 and all seems fine now .
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