1993 Corvette AC Problem
Thread Starter
4th Gear
Joined: Jul 2022
Posts: 4
Likes: 0
1993 Corvette AC Problem
Hello everyone. I'm having a problem with my AC, in which it only blows hot air. I checked the pressure of the system and it was fully pressurized. The first thing I noticed was that the clutch for the compressor wasn't coming on. I'd read that the high and low pressure switches could be the issue. I read that you can bypass the low pressure switch by shorting the two female connectors together with a paperclip. I did so and the clutch briefly engaged before never coming on again, even with the connectors shorted together. I also got the 09 code from the thermostat. I thought the low pressure switch was the issue, so I replaced it, but it didn't fix it. I couldn't angle my multimeter probes the right way to check resistance, so jumping the connectors together was the only way I knew how to test the switches. Is there something else I should be looking for?
Zen Vet Master Level VII
Joined: Mar 2016
Posts: 5,218
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From: Southlake, TX
Melting Slicks
Joined: Jan 2014
Posts: 2,192
Likes: 381
From: Lunenburg MA
Drifting
Joined: Jun 2013
Posts: 1,965
Likes: 343
From: Shell Point (Crawfordville) Florida
As long as you have the 09 code, your compressor will not go on even with shorting the low pressure switch. You must first eliminate the code by disconnecting the battery for 15-30 sec., then with the code gone, short the switch to engage the compressor and add Freon. You cannot add Freon if the compressor is not running.
Or bring it to someone who knows what they are doing, and find the source of the Freon leak otherwise you will soon be back where you started form.
Or bring it to someone who knows what they are doing, and find the source of the Freon leak otherwise you will soon be back where you started form.
Burning Brakes
Joined: Aug 2018
Posts: 891
Likes: 175
From: PA
In 2019 my 91 ZR1 needed freon . I took it to a local shop that added freon while I watched . The code 09 was still present . They hooked it up to their machine and added just under 2 lbs of 134A . They had no issues filling the system . Afterwards it was still blowing hot air . I called Marc Haibeck the ZR1 specialist who told me to disconnect the positive battery terminal and it should work . Sure enough the code was reset and it started blowing cold .
What I wonder is how is it that no one can add freon with the compressor not working when doing it using say an AC pro/ their own hose and gauges but the guys at the shop had no issue filling the system. Yes the compressor was not running. They even tried to jump it at the switch and didn't understand as long as that code was present it would not run. Once the code was reset it came right on and the system worked.
What I wonder is how is it that no one can add freon with the compressor not working when doing it using say an AC pro/ their own hose and gauges but the guys at the shop had no issue filling the system. Yes the compressor was not running. They even tried to jump it at the switch and didn't understand as long as that code was present it would not run. Once the code was reset it came right on and the system worked.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
In 2019 my 91 ZR1 needed freon . I took it to a local shop that added freon while I watched . The code 09 was still present . They hooked it up to their machine and added just under 2 lbs of 134A . They had no issues filling the system . Afterwards it was still blowing hot air . I called Marc Haibeck the ZR1 specialist who told me to disconnect the positive battery terminal and it should work . Sure enough the code was reset and it started blowing cold .
What I wonder is how is it that no one can add freon with the compressor not working when doing it using say an AC pro/ their own hose and gauges but the guys at the shop had no issue filling the system. Yes the compressor was not running. They even tried to jump it at the switch and didn't understand as long as that code was present it would not run. Once the code was reset it came right on and the system worked.
What I wonder is how is it that no one can add freon with the compressor not working when doing it using say an AC pro/ their own hose and gauges but the guys at the shop had no issue filling the system. Yes the compressor was not running. They even tried to jump it at the switch and didn't understand as long as that code was present it would not run. Once the code was reset it came right on and the system worked.
At a shop with professional equipment they can put in a measured amount with a pump that has more pressure than the system at rest (static). Which is why they can fill it without it running.
1st Gear
Joined: Oct 2024
Posts: 1
Likes: 0
AC issue
93 Corvette Running hot. AC clutch would not come on for AC or defrost. Main fan would not come on till 235F. Checked coolant recovery tank, which was low. Added coolant. Disconnected battery fór 1 minute or so as previous poster did. Started car up, AC clutch ing engaging and AC working, Car not driven much.
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