a/c dead
Thread Starter
TECH Apprentice
Joined: Jul 2012
Posts: 369
Likes: 4
a/c dead Well after finishing my oil pan job the a/c is dead. Warm air blowing out. 120psi on high side, 60psi on both when neutral. The compressor is turning over. Its not taking any R134A thru the low side. What could be the problem.
Thread Starter
TECH Apprentice
Joined: Jul 2012
Posts: 369
Likes: 4
Where was the wire located and was it preventing the compressor from turning on? My compressor/clutch is turning over. The only wires I can think of in the engine compartment are the high pressure switch and the compressor clutch wire. 120 psi on the high side with compressor running sounds like a mechanical problem. Should be around 300+
TECH Fanatic
Joined: Nov 2011
Posts: 1,367
Likes: 144
From: Woodstock, GA
Where was the wire located and was it preventing the compressor from turning on? My compressor/clutch is turning over. The only wires I can think of in the engine compartment are the high pressure switch and the compressor clutch wire. 120 psi on the high side with compressor running sounds like a mechanical problem. Should be around 300+
It sounds like the compressor clutch is engaging and it sounds like it’s cycling on/off as designed. Undercharge sounds likely as well. You should be able to get more refrigerant into the system but it will need to be done while the clutch is engaged and the low pressure side (compressor suction) is at its lowest ~ 25-30 psi. Are you using an AC manifold gauge set? And only trying to add via the low pressure blue side?
Also, you didn’t mention what car you’re working on but I’ve seen some HVACs cause issues when a vacuum line leaked or was left disconnected after some work under the hood. Have you checked there?
Also, you didn’t mention what car you’re working on but I’ve seen some HVACs cause issues when a vacuum line leaked or was left disconnected after some work under the hood. Have you checked there?
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Depends on the vehicle. That said, I’ve seen blend doors working incorrectly and even some vac operated heater valves malfunction due to a vac leak or disconnected vac line. These conditions make it seem like the ac is not working when in reality it’s the blend doors and/or heater valve that are blowing warm air when they shouldn’t be.
Based on your first post I would recommend getting an ac manifold set (some parts stores rent them for FREE) and make sure your ac system is fully charged first. Then make sure the compressor is cycling on and off as it should. You should be able to hear a click and see the inner compressor hub start and stop if the system pressures are normal or at least near normal. If the system is charged but the compressor is not cycling on/off, then check the high and low cutoff switches, compressor wiring and connectors and any fuses and relays in the ac system. It’s easy to use a paper clip to jumper the cutoff switches to test them. If all that checks out ok, then that would mean the ac system is working and the problem may be in the blend doors not directing the vent air correctly (possibly from a vac leak).
Based on your first post I would recommend getting an ac manifold set (some parts stores rent them for FREE) and make sure your ac system is fully charged first. Then make sure the compressor is cycling on and off as it should. You should be able to hear a click and see the inner compressor hub start and stop if the system pressures are normal or at least near normal. If the system is charged but the compressor is not cycling on/off, then check the high and low cutoff switches, compressor wiring and connectors and any fuses and relays in the ac system. It’s easy to use a paper clip to jumper the cutoff switches to test them. If all that checks out ok, then that would mean the ac system is working and the problem may be in the blend doors not directing the vent air correctly (possibly from a vac leak).
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