Ac compressor stopped working out of nowhere

644 Views 6 Replies 2 Participants Last post by Bange2001, 2 mo ago

Bange2001

Discussion Starter · 2 mo ago

I have a 2015 Cruze, 1.8 engine, 6 speed manual transmission, on my way to work today my ac was working just fine, and on the way back home from work when I turned on the ac, it was blowing out outside temperature air. I checked the compressor relay by swapping it with an identical relay in the fuse box, and still nothing. I have a bidirectional scanner and I commanded on the ac clutch relay and you can hear it click, and I turned on the radiator fan with the scanner and it came on. With my scanner live data, it had a section on there that said “high side pressure Psi 90” I do not know if that is normal or not, I can check the pressures with a gauge set but if the compressor won’t come on at all I’m not sure if that’ll tell me anything. I’m not sure if it’s leaking refrigerant because I’ve never had any problems with the ac not working or even blowing warm, it’s always been nice and cold, the only problem I’ve had was a rough idle with the ac on before. And the weird thing is now, when I turn on the ac switch, it makes the same sound as if the ac actually worked and the rpm drop a tiny bit for a second, but the compressor clutch is not engaged. I’m inclined to believe that it’s something electrical, only because it just went bad out of nowhere. But I do see some damp spot on the compressor, so maybe it could have a refrigerant leak, but maybe it’s blowback from a small oil pan gasket leak, it just seems odd though how it went bad in one second like that. Thank you all for any help.

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rprado

· #2 · 2 mo ago

Check the refrigerant pressure and the pressure sensor if its working then the evaporator sensor in the cabin underneath the center dashboard. Mine has same issue but after all the testing, I have figured it out that the Evaporator sensor is the culprit. you can check the resistance if its too low, shorted to ground or busted. Good sensor(thermistor) has 950~1150ohms, consider replacing if its too low or high.

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Bange2001

Discussion Starter · #3 · 2 mo ago

rprado said:
Check the refrigerant pressure and the pressure sensor if its working then the evaporator sensor in the cabin underneath the center dashboard. Mine has same issue but after all the testing, I have figured it out that the Evaporator sensor is the culprit. you can check the resistance if its too low, shorted to ground or busted. Good sensor(thermistor) has 950~1150ohms, consider replacing if its too low or high.

Thank you for responding. I was going to check the voltage going to the pressure sensor too, it’s a 3 wire sensor, but I’ll also check that evaporator sensor. Do you know what a good resistance reading is for the pressure switch? And which color wire for the pressure switch is the 5v reference? I was thinking of jumpering it to bypass the switch just to see if the compressor kicks in real quick, because if I can bypass that pressure sensor on the condenser, and if it kicks on the compressor, then that means that pressure sensor is bad, right?

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Bange2001

Discussion Starter · #4 · 2 mo ago

So I hooked up my scan tool and found out that the high side pressure is really low now, the reading is about 50 psi. I unplugged the pressure switch sensor and it read 0. The live data stream says the compressor is engaged when it is not, so the computer thinks the compressor is engaged, so I’m guessing the electrical part of the system is good. I used a refrigerant leak detector and when I moved it on the condenser on one spot it beeped really fast, however I could not duplicate that again or find the exact same spot again. I might try adding refrigerant and see if the compressor kicks on. Maybe I have a small leak somewhere. Below is a picture of the live data, it says compressor clutch engaged when it was not.

Personal computer Motor vehicle Output device Computer Automotive exterior

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Bange2001

Discussion Starter · #5 · 2 mo ago

I recovered and vacuum tested the system and it passed the leak test , and I charged it to spec. Compressor still does not turn on. I’m thinking now I want to test the pressure switch, does anyone know what the resistance specification should be on that? It’s a 3 prong connection, there are two prongs side by side and the other one I guess is a 5v reference signal from the pcm. I would like to know if there is a specification that I can test with an ohmmeter, and if anyone could find a wiring diagram for the ac system I would much appreciate it, I have a 2015 Cruze LS. Thanks.

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rprado

· #6 · 2 mo ago

The A/C refrigerant pressure sensor is a 3-wire piezoelectric pressure transducer. A 5 V reference voltage, low
reference, and signal circuits enable the sensor to operate. The A/C pressure signal can be between 0.2-4.8 V.
When the A/C refrigerant pressure is low, the signal value is near 0 V. When the A/C refrigerant pressure is
high, the signal value is near 5 V. The engine control module (ECM) converts the voltage signal to a pressure
value. When pressure is too high or too low, the ECM will not allow the A/C compressor clutch to engage.

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Bange2001

Discussion Starter · #7 · 2 mo ago

rprado said:
The A/C refrigerant pressure sensor is a 3-wire piezoelectric pressure transducer. A 5 V reference voltage, low
reference, and signal circuits enable the sensor to operate. The A/C pressure signal can be between 0.2-4.8 V.
When the A/C refrigerant pressure is low, the signal value is near 0 V. When the A/C refrigerant pressure is
high, the signal value is near 5 V. The engine control module (ECM) converts the voltage signal to a pressure
value. When pressure is too high or too low, the ECM will not allow the A/C compressor clutch to engage.

Thank you. I used the ronin air cool tech machine and recovered vacuumed and leak tested the system, no refrigerant leaks and my pressure switch was accurate because it read what the gauges were reading. The next day I checked the power going to the compressor clutch coil and internal compressor switch, I have power to it. I did a resistance test on the coil and it only read 0.5 ohms, and from my research coils need to be between 3 and 5 ohms, so my coil is shorted out internally. I will replace the coil and see if that fixes it.

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Ac compressor stopped working out of nowhere

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