93 LT1 a/c problem recurring????
Thread Starter
Intermediate
Joined: Sep 2008
Posts: 41
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93 LT1 a/c problem recurring????
93 LT1 a/c problems back?
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Thought i had soughted my 93 LT1 (climate air) a/c problem, originally code 9 'low freon", replaced both high and low pressure switches, checked fuses, connections, cleared codes (removing neg batt cable) re-gassed....run dye through, no leaks, operated again for a couple of days, ran perfectly........ out the other day, remarked to the wife, good to have a/c going again, then right at that point, a/c stopped again, blowing warm air. Air con guy checked this morning, still gassed, and compressor not coming on??
Is this now an electrical/electronic issue? i heard some 90/91 models has stereo issues,( buttons jamming, only some functions working), and some reported a/c issues at the same time, and fixing the stereo issues fixed the a/c issues at the same time, does anyone know whether this applied to 93's also? ( delco service bulletin no. RD91TBA03 )
see previous post.
--------------------------------------------------------------------------------
Thought i had soughted my 93 LT1 (climate air) a/c problem, originally code 9 'low freon", replaced both high and low pressure switches, checked fuses, connections, cleared codes (removing neg batt cable) re-gassed....run dye through, no leaks, operated again for a couple of days, ran perfectly........ out the other day, remarked to the wife, good to have a/c going again, then right at that point, a/c stopped again, blowing warm air. Air con guy checked this morning, still gassed, and compressor not coming on??
Is this now an electrical/electronic issue? i heard some 90/91 models has stereo issues,( buttons jamming, only some functions working), and some reported a/c issues at the same time, and fixing the stereo issues fixed the a/c issues at the same time, does anyone know whether this applied to 93's also? ( delco service bulletin no. RD91TBA03 )
see previous post.
Le Mans Master
Joined: May 1999
Posts: 6,513
Likes: 1,301
From: Windermere FL
Let me post what happened to me. I lost all my R12 in a leak and had to go with R134. Conversion worked well, but after a long while the compressor would not run - low pressure but freon was full.
Turned out that the stock R12 low pressure sensor switch is sensitive to R134. I R&R the sensor (available inexpensively at AutoZone) and the problem went away. Turns out there are some set screws on the sensor that can be adjusted for the lower pressures of R134 but I did not tweak them on my new sensor and it has been fine for years. Not sure if tweaking yours will help or not. You can briefly short out the leads and see if the compressor starts.
I am not sure if you converted, or if this is your problem, but it might be if you converted to R134.
Turned out that the stock R12 low pressure sensor switch is sensitive to R134. I R&R the sensor (available inexpensively at AutoZone) and the problem went away. Turns out there are some set screws on the sensor that can be adjusted for the lower pressures of R134 but I did not tweak them on my new sensor and it has been fine for years. Not sure if tweaking yours will help or not. You can briefly short out the leads and see if the compressor starts.
I am not sure if you converted, or if this is your problem, but it might be if you converted to R134.
Last edited by Flame Red; Feb 5, 2011 at 07:38 AM.
Thread Starter
Intermediate
Joined: Sep 2008
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Thanks guys, mine is still on the old R12, which the a/c guy still had some and was able to regas with R12, but I have replaced both pressure switches, low pressure switch with GM part, and high pressure with aftermarket (may be the other way around)....unfortunately still being microwaved on a drive with the glass roof, was wondering whether I should pull out the climate control head unit and clean the connections as described in some other a/c posts??, or would this be futile as the problem may lie somewhere else?
Pro
Joined: Aug 2009
Posts: 725
Likes: 4
From: Plano, TX
Well I have a similar problem which may or may not be related. The AC programmer fails to ground the ac request line to the ecm. The ac request should be grounded whenever the c68 system deems that the ac compressor needs to run to make the temperature right. I could not figure it out so I had to cut the blue wire going into the c68 ac programmer and manually ground it with a toggle switch. I've been chasing wires for some time now and have pretty much come the conclusion that the ac programmer or control head is bad.
The ac runs fine as long as I flip my toggle switch to turn on the compressor. I just don't like leaving my forgetful brain in charge of the ac compressor. I'd rather the C68 control this as opposed to me.
The ac runs fine as long as I flip my toggle switch to turn on the compressor. I just don't like leaving my forgetful brain in charge of the ac compressor. I'd rather the C68 control this as opposed to me.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Sounds like an intermittent connection at the Low Pressure Switch (since you've replaced it). System is monitored for a Low Charge - rapid cycling or opening and closing of the Low Pressure Switch contacts and that sets the Low Gas Code - which it doesn't have. It also monitors static pressure from the Pressure Sensor - normally about .8 volts or 80 psi; looks for a rise in voltage (pressure) when the clutch engages and if it doesn't that will kill it (indicating a broken compressor). It will also shutdown if the Sensor indicates 400 psi or better (about 4 volts) to keep it from blowing a hole in the hood. You could scan it to see the Pressure Sensor signal, but I'd try disconnecting and reconnecting the Low Pressure Switch or wriggling around the harness the next time this happens. If it works, you need a new Connector.
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Thread Starter
Intermediate
Joined: Sep 2008
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Once again, thanks for your input everyone, mechanicals, not being my forte, I now have the vette booked in with the auto electrician on Monday morn to confirm whether it is an elec fault or a/c fault, have printed out all the quotes and will supply fsm to him, hopefully they will get to the bottom of it. Will report outcome once I know, once again, thank you all for your time, Colin (NZ)
Instructor
Joined: May 2010
Posts: 135
Likes: 1
From: Oklahoma
AC wiring help
Ok I've had that same problem with my AC giving a code 09. I've unplugged my battery to reset it but it kicks off in about 10 minutes. I've read about someone wiring in a toggle switch and decided to give this a try. I was wondering which wire I need to give power to, to power on the compressor. If anyone could show me a pic of which wire it is that would be great. thanks.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
It's designed the way it was for convenience and SAFETY. Overriding the Low Pressure Switch and/or Pressure Sensor is a good way to blow it up. Start by getting the operating pressures. If you don't have the equipment, go to a shop. Most will do that much for a reasonable fee (if anything) because they can make plenty to fix what's really wrong with it. When you know what that is - post it for some real help.
Melting Slicks
Joined: Aug 2000
Posts: 2,961
Likes: 1
From: Sealy Texas
Cruise-In III Veteran
Well I have a similar problem which may or may not be related. The AC programmer fails to ground the ac request line to the ecm. The ac request should be grounded whenever the c68 system deems that the ac compressor needs to run to make the temperature right. I could not figure it out so I had to cut the blue wire going into the c68 ac programmer and manually ground it with a toggle switch. I've been chasing wires for some time now and have pretty much come the conclusion that the ac programmer or control head is bad.
The ac runs fine as long as I flip my toggle switch to turn on the compressor. I just don't like leaving my forgetful brain in charge of the ac compressor. I'd rather the C68 control this as opposed to me.
The ac runs fine as long as I flip my toggle switch to turn on the compressor. I just don't like leaving my forgetful brain in charge of the ac compressor. I'd rather the C68 control this as opposed to me.
Burning Brakes
Joined: Apr 2009
Posts: 877
Likes: 0
From: Broken Arrow Oklahoma
yes there is a relay on my 90.Located on the drivers side behind the knee bolster.
If you have 12 volts coming out of the relay, it sends a signal to the ECM for A/C request. The ECM sends a signal to the LP switch, if you have the correct amount of Freon then the LP switch sends the ground signal to the clutch.
there is one green wire that comes out of the ECM and goes to the LP switch.
At least this is how I think I remember when I fixed mine.
If you have 12 volts coming out of the relay, it sends a signal to the ECM for A/C request. The ECM sends a signal to the LP switch, if you have the correct amount of Freon then the LP switch sends the ground signal to the clutch.
there is one green wire that comes out of the ECM and goes to the LP switch.
At least this is how I think I remember when I fixed mine.
