94 A/C Problems....suggestions wanted
Thread Starter
6th Gear
Joined: Oct 2018
Posts: 6
Likes: 0
94 A/C Problems....suggestions wanted
Hey everyone, new to the forum! I have a 94 corvette with A/C problems that are driving me insane. I took the car into the chevy dealer and was told that the digital a/c module on the dash is bad. They drained the system and recharged it but it did not solve the issue. I do not think they could find the problem with the system and this was the only answer they could come up with. ALL of the buttons on the A/C light up, mine never blink. No A/C codes to check on the digital readout. The A/C clutch is not coming on when I start the car. I took the connection off of the two wire A/C pressure cycling switch and jumped either side with a paperclip......when I did this the clutch engaged for the first time since I have owned the car (only a week or so). I bought a new cycling switch and it did not fix the problem......This leads me to believe that it is actually the AC module on the dash, like the dealer was saying, or it is a computer issue. I am glad to see the Clutch finally working and that I do not have a bad compressor, but I am trying to get down to the bottom of this issue.....electrical issues can be a pain to find.....does anyone have any suggestions on what my issue might be? Any feedback is greatly appreciated! Thanks!
Thread Starter
6th Gear
Joined: Oct 2018
Posts: 6
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Melting Slicks
Joined: Jan 2014
Posts: 2,192
Likes: 381
From: Lunenburg MA
Thread Starter
6th Gear
Joined: Oct 2018
Posts: 6
Likes: 0
Have you looked at http://batee.com/ ?
thanks for that link. It looks like I'm going to need to find the A/C relay and see if i have any luck there. Batee.com says its under the instrument panel on the LH side but I can't find it......has anyone had any luck locating it?
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
The AC relay in kind of under the surge tank on the passenger side bolted to the wheel well. It's hidden under all the hoses and such. Those relays usually last forever and usually not the cause of your problem. BUT if you jumped the cycling switch and the compressor came on, then the relay is working. So your problem is not the relay.
There is lots of items that can cause your problem, short on time now but I will get some items you can check later.
Does the control head indicate the outside ambient temperature and all buttons appear to work?
There is lots of items that can cause your problem, short on time now but I will get some items you can check later.
Does the control head indicate the outside ambient temperature and all buttons appear to work?
Thread Starter
6th Gear
Joined: Oct 2018
Posts: 6
Likes: 0
The AC relay in kind of under the surge tank on the passenger side bolted to the wheel well. It's hidden under all the hoses and such. Those relays usually last forever and usually not the cause of your problem. BUT if you jumped the cycling switch and the compressor came on, then the relay is working. So your problem is not the relay.
There is lots of items that can cause your problem, short on time now but I will get some items you can check later.
Does the control head indicate the outside ambient temperature and all buttons appear to work?
There is lots of items that can cause your problem, short on time now but I will get some items you can check later.
Does the control head indicate the outside ambient temperature and all buttons appear to work?
Racer
Joined: Jul 2017
Posts: 422
Likes: 53
From: PA
Hey everyone, new to the forum! I have a 94 corvette with A/C problems that are driving me insane. I took the car into the chevy dealer and was told that the digital a/c module on the dash is bad. They drained the system and recharged it but it did not solve the issue. I do not think they could find the problem with the system and this was the only answer they could come up with. ALL of the buttons on the A/C light up, mine never blink. No A/C codes to check on the digital readout. The A/C clutch is not coming on when I start the car. I took the connection off of the two wire A/C pressure cycling switch and jumped either side with a paperclip......when I did this the clutch engaged for the first time since I have owned the car (only a week or so). I bought a new cycling switch and it did not fix the problem......This leads me to believe that it is actually the AC module on the dash, like the dealer was saying, or it is a computer issue. I am glad to see the Clutch finally working and that I do not have a bad compressor, but I am trying to get down to the bottom of this issue.....electrical issues can be a pain to find.....does anyone have any suggestions on what my issue might be? Any feedback is greatly appreciated! Thanks!
I had similar problems to you in my 96 with climate control, buttons would not work, i did this and it fixed it.
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Melting Slicks
Joined: May 2014
Posts: 2,894
Likes: 592
From: New Port Richey FL
Everything you mentioned is the same stuff I went Thru on my 93, but I had to Undo all the Bad things the Previous Owner did Like He put in and I'm Not shore if was a 94 or 95 Control head, He Ran a hot wire from Blower motor to Compressor. Once I had the car back to Correct G.M. parts and Configuration. I was right where you are, what I found was that my A/C control Module was bad, That's not what you see in the dash but Hidden above the Brake Peddle on the Fire wall
Last edited by s carter; Oct 2, 2018 at 01:04 PM.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
As I sat back getting my books out and formulating a plan of points to test and things to do it suddenly occurred to me and don’t want to lead you off into left field.
Many things have to work to start the compressor like the control head, programmer, PCM and high pressure sensor just to mention a few.
However when you jumped the connector with the paperclip and the compressor started that tells me all is working if I understand all that you have said. It almost seems to me that there is not enough pressure in the system to close the cycling switch. Connecting a set a gauges on it would tell you right away. Also you could check the resistance of the switch to see if it is closed and has "0" ohm.
What I don’t understand is how the dealer was able to charge the system IF the compressor was not running. This makes no sense at all and who knows what they were doing or told you. If there is some information I don’t know that might help. But you can't charge a system that is not running.
You might want to go to an automotive A/C shop and get a free check giving them all the information you know and see what their opinion is and what they think needs to be done.
Many things have to work to start the compressor like the control head, programmer, PCM and high pressure sensor just to mention a few.
However when you jumped the connector with the paperclip and the compressor started that tells me all is working if I understand all that you have said. It almost seems to me that there is not enough pressure in the system to close the cycling switch. Connecting a set a gauges on it would tell you right away. Also you could check the resistance of the switch to see if it is closed and has "0" ohm.
What I don’t understand is how the dealer was able to charge the system IF the compressor was not running. This makes no sense at all and who knows what they were doing or told you. If there is some information I don’t know that might help. But you can't charge a system that is not running.
You might want to go to an automotive A/C shop and get a free check giving them all the information you know and see what their opinion is and what they think needs to be done.
Last edited by pcolt94; Oct 3, 2018 at 09:54 AM.
Team Owner
Joined: Jul 2004
Posts: 28,472
Likes: 3,290
From: Hartford WI
As I sat back getting my books out and formulating a plan of points to test and things to do it suddenly occurred to me and don’t want to lead you off into left field.
Many things have to work to start the compressor like the control head, programmer, PCM and high pressure sensor just to mention a few.
However when you jumped the connector with the paperclip and the compressor started that tells me all is working if I understand all that you have said. It almost seems to me that there is not enough pressure in the system to close the cycling switch. Connecting a set a gauges on it would tell you right away. Also you could check the resistance of the switch to see if it is closed and has "0" ohm.
What I don’t understand is how the dealer was able to charge the system IF the compressor was not running. This makes no sense at all and who knows what they were doing or told you. If there is some information I don’t know that might help. But you can't charge a system that is not running.
You might want to go to an automotive A/C shop and get a free check giving them all the information you know and see what their opinion is and what they think needs to be done.
Many things have to work to start the compressor like the control head, programmer, PCM and high pressure sensor just to mention a few.
However when you jumped the connector with the paperclip and the compressor started that tells me all is working if I understand all that you have said. It almost seems to me that there is not enough pressure in the system to close the cycling switch. Connecting a set a gauges on it would tell you right away. Also you could check the resistance of the switch to see if it is closed and has "0" ohm.
What I don’t understand is how the dealer was able to charge the system IF the compressor was not running. This makes no sense at all and who knows what they were doing or told you. If there is some information I don’t know that might help. But you can't charge a system that is not running.
You might want to go to an automotive A/C shop and get a free check giving them all the information you know and see what their opinion is and what they think needs to be done.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Yes.
You could have run external 12 volts to the compressor clutch, or as the OP said, you could have the jumped out the cycling switch and started the compressor (to name a couple).
But as I said, I don’t know what they exactly did and I think there are pieces of information missing.
When the cycling switch was jumped out, that tells me the control head and programmer are feeding the ON signal to the cycling switch which in turn tells the PCM to close the AC relay which started the compressor. Given this scenario, I don’t think all the facts are known.
You could have run external 12 volts to the compressor clutch, or as the OP said, you could have the jumped out the cycling switch and started the compressor (to name a couple).
But as I said, I don’t know what they exactly did and I think there are pieces of information missing.
When the cycling switch was jumped out, that tells me the control head and programmer are feeding the ON signal to the cycling switch which in turn tells the PCM to close the AC relay which started the compressor. Given this scenario, I don’t think all the facts are known.