A/C working but not working
Thread Starter
5th Gear
Joined: Apr 2021
Posts: 5
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A/C working but not working
I've been troubling shooting the A/C system on my 1993 Anniversary Corvette. It's been converted to R134a, replaced cycling switch. This has C68 electronic climate control. The climate computer is not throwing any error codes, all the temp sensors seem to be operational. The AC clutch works when manually jumped. The AC relay works when manually jumped, the AC system cycles and blows cold when manually bypassed. The wires from the ECM to the sensors and relay all Ohm out as connected.
It seems as if the climate control isn't sending the signal to turn the AC on and I've come to the end of my ability to trouble shoot this. Looking for more options from anyone who might have experience with this. Is it possible someone has disabled the AC from turning on inside the computer show how? I got the car with the AC non-functional.
Thanks
It seems as if the climate control isn't sending the signal to turn the AC on and I've come to the end of my ability to trouble shoot this. Looking for more options from anyone who might have experience with this. Is it possible someone has disabled the AC from turning on inside the computer show how? I got the car with the AC non-functional.
Thanks
Thread Starter
5th Gear
Joined: Apr 2021
Posts: 5
Likes: 0
Oddly enough, someone has hardwired both cooling fans to come on when the ignition is on. So they are always on despite what the climate control is doing. I don't even know where that hot-wire has been done at.
Drifting
Joined: Aug 2019
Posts: 1,339
Likes: 225
There should be a high pressure switch. If that switch is closed/shorted, the ac will turn off, and turn on the cooling fans. That may be why the fans turn on and the ac never comes on. It thinks the system pressure is too high, and is in self protect mode.
Thread Starter
5th Gear
Joined: Apr 2021
Posts: 5
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I traced all the AC pressure lines. I could only find the pressure cycling switch which i converted to R134a pressures, and the 3 wire high pressure transducer which I also replaced thinking maybe it was faulty. The Transducer has a 5v signal a ground, and what appears to be a composite voltage two tell the computer the current pressure. All that seems to be functional.. If there is a separate high pressure sensor I haven't found it anywhere on the lines, evaporator, condenser, anywhere that I can see.
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Verdad Gallardo
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From: Cape Coral, Florida
I've been troubling shooting the A/C system on my 1993 Anniversary Corvette. It's been converted to R134a, replaced cycling switch. This has C68 electronic climate control. The climate computer is not throwing any error codes, all the temp sensors seem to be operational. The AC clutch works when manually jumped. The AC relay works when manually jumped, the AC system cycles and blows cold when manually bypassed. The wires from the ECM to the sensors and relay all Ohm out as connected.
It seems as if the climate control isn't sending the signal to turn the AC on and I've come to the end of my ability to trouble shoot this. Looking for more options from anyone who might have experience with this. Is it possible someone has disabled the AC from turning on inside the computer show how? I got the car with the AC non-functional.
Thanks
It seems as if the climate control isn't sending the signal to turn the AC on and I've come to the end of my ability to trouble shoot this. Looking for more options from anyone who might have experience with this. Is it possible someone has disabled the AC from turning on inside the computer show how? I got the car with the AC non-functional.
Thanks
Last edited by C5 Diag; Apr 11, 2021 at 11:25 PM.
Thread Starter
5th Gear
Joined: Apr 2021
Posts: 5
Likes: 0
Not 100% sure what inputs you can see with a scan tool on a ‘93 but things like ECT, AC pressure sensor etc if your new system has that..it’s a 3 wire sensor...my C5 uses a class 2 serial data message from the HVAC head to the PCM but yours may use a 12 volt wire directly to the PCM...with a scan tool you can check the AC Request data PID...when you push the AC button you should see “YES”on the scan tool.We had a C5 member whose AC would cut off when he came to a stop...a tuner fixed that issue !!