AC Compressor coming on when it feels like it
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Joined: Jun 2023
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From: Orlando
AC Compressor coming on when it feels like it
Okay all. Need your help with my 1993 base model coupe. My compressor is less than 60 days old. I changed my car back to R12 about 4 months ago. Out of no where my compressor started working when it feel like it. I thought it was the ECM. I had the ECM refurbished and that did not work. Any reasons why my compressor is coming on arbitrarily? Sometimes my meter shows power going to the compressor and sometimes it doesn't. Should I rewire the whole thing?
Last edited by Vinny37; Nov 20, 2024 at 10:33 AM.
Melting Slicks
Joined: Feb 2003
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From: Saskatoon Sask.
Okay all. Need your help with my 1993 base model coupe. My compressor is less than 60 days old. I changed my car back to R12 about 4 months ago. Out of no where my compressor started working when it feel like it. I thought it was the ECM. I had the ECM refurbished and that did not work. Any reasons why my compressor is coming on arbitrarily? Sometimes my meter shows power going to the compressor and sometimes it doesn't. Should I rewire the whole thing?
Melting Slicks
Joined: Nov 2016
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From: So Cal
2023 C4 of the Year Finalist - Unmodified
I'm assuming the OP has C68 electronic controls. There's a lot of places this system can misbehave. The control head is connected to the programmer, the programmer sends a 'Compressor ON request' to the ECM, the ECM controls the A/C clutch relay, and the relay sends power to the compressor clutch. The clutch itself can also misbehave by not always engaging when power is present.
The compressor can/may be commanded ON in all modes except OFF and VENT (5th button from the left, arrows pointing at face level). What Mode(s) is it in when "compressor comes on when it feels like it?"
If the clutch is really engaging when it shouldn't be, I'd begin by putting a scanner on it and monitoring the "clutch request" input at the ECM. If compressor engagement follows the request input correctly, then the 'problem' is in the C68 components. You can also monitor the a/c clutch control output. Again, does the clutch follow the command?
My hunch is that the OP doesn't have access to testing equipment or the Service Manuals, and will be guessing as to what the problem is, if there is one at all. He's using his mechanics.
The compressor can/may be commanded ON in all modes except OFF and VENT (5th button from the left, arrows pointing at face level). What Mode(s) is it in when "compressor comes on when it feels like it?"
If the clutch is really engaging when it shouldn't be, I'd begin by putting a scanner on it and monitoring the "clutch request" input at the ECM. If compressor engagement follows the request input correctly, then the 'problem' is in the C68 components. You can also monitor the a/c clutch control output. Again, does the clutch follow the command?
My hunch is that the OP doesn't have access to testing equipment or the Service Manuals,
Last edited by IHBD; Nov 20, 2024 at 01:14 PM. Reason: OP has had the car 5 years. He appreaciated the input. I lightened it up.
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Joined: Jun 2023
Posts: 66
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From: Orlando
I have had the car for 5 years. Thank you for the step by step of how it works. The mode that I mostly use is Auto and the symbol for in cabin circulate. The AC does work in a bunch of modes, but these two are the primary that I use. Sometimes I let it go through the vents and at my feet (the combo button) and that runs the AC as well.
I'm going to show my mobile mechanic all of this and ask him to test it. Thank you so much! My mechanics have access all testing equipment. I have an electrical mechanic and an auto mechanic. Both have failed so far, but I'm going to send them this. I'll let you know how it goes.
I'm going to show my mobile mechanic all of this and ask him to test it. Thank you so much! My mechanics have access all testing equipment. I have an electrical mechanic and an auto mechanic. Both have failed so far, but I'm going to send them this. I'll let you know how it goes.
