Ok, after a long winter, I find my AC doesn't blow cold. I replaced an evaporator 3 years ago and thought for sure I must have a slow leak. After vaccing and verifying no leaks and trying to recharge, the compressor won't kick on even when the low side pressure got pretty high. From the FSM I checked resistance at the plug and got 900 some ohms (within spec) and shorted the mag clutch with the battery and it works fine. What now? No sign of a leak and the two things the service manual says are fine.
Ac compressor diagnosis help
- Thread starter mr111
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what are your readings when you jump the clutch? (low side) I would bet you might be a few oz low on your charge... pretty rare for the pressure switch to go bad... but it happens...
jumping the clutch is what I do to charge any automotive system... but I'm pretty unorthodox when it comes to AC systems and what I think they can do... I believe they should be blowing chunks of ice out the vents and I screw with them until I think I'm close... I try to charge using the super heat schedule but I usually revert to a probe in the air coming out of the vents... and charge to that... (on a hot day) with a lot of air flow on the front of the truck (large misting fans)
jumping the clutch is what I do to charge any automotive system... but I'm pretty unorthodox when it comes to AC systems and what I think they can do... I believe they should be blowing chunks of ice out the vents and I screw with them until I think I'm close... I try to charge using the super heat schedule but I usually revert to a probe in the air coming out of the vents... and charge to that... (on a hot day) with a lot of air flow on the front of the truck (large misting fans)
what was your low side WITH the compressor turning/ engaged? you can get a high low side reading and not get the clutch to energize...
- Thread starter
- #5
That's actually where I stopped. Since the compressor clutch didn't engage, I didn't see any point to wasting more refrigerant. I can certainly short the clutch and charge more, but if it wasn't cycling doesn't that already indicate a problem? What could I learn from manually cycling it and then filling it?
That is exactly what I would do... engage the clutch and watch my low side pressure... I bet after running ..... high fan coldest temp on your low side pressure will be below 30