Welcome to the Corvette Forums at the Corvette Action Center!

AC problems/questions



OK guys, my AC has suddenly stopped blowing cold, or even cool, air.

When I get in and start my baby up, my electronic AC contol units LED, above the off button, blinks on and off instead of staying on like it normally does.

What is going on? Do I have a problem with the contol unit? What exactly does the blinking LED mean?

Thanks guys.
AC torubles?

I might be wrong here but I seem to remember something about troubleshooting your AC like you would access your cars trouble codes. It would blink giving you trouble codes. but you have to have the manual or know someone that has one.
e-mail me @ edwardth@spole.gov I might be able to put you in contact with someone with allot more knowledge than I have on the C4s.
Silver is correct

Yes, you have a diagnostic trouble code in the HVAC system, and that is what makes the light flash.
My guess is that you have a code 9, which is low freon detected. You will have to see if the compressor is cycling on and off, if not, I would say that you have a freon leak, and will have to have it diagnosed.
Best to you, c4c5
WOW!!! Fast response!

Thanks. I get out of class early today and will try getting it looked at. It's starting to get a bit unbearable.
This might sound really dumb, but try disconnecting your battery for a few minutes. My ZR-1 went through the same problem and I heard that little trick fixes it. I'm not sure if that's a ZR-1 thing only or what, but it's worth a shot.

JT ZR-Won said:
This might sound really dumb, but try disconnecting your battery for a few minutes. My ZR-1 went through the same problem and I heard that little trick fixes it. I'm not sure if that's a ZR-1 thing only or what, but it's worth a shot.


Hey, it worked for someone in another thread! :D
I took my Vette in today to get the AC system recharged. They checked the system out first and found that the compressor was not turning on. They checked both pressure switches wiring and had no voltage.

The mechanic then ran 12vdc from the battery directly to the compressor and the clutch engaged.

He said there is a problem in the wiring and mentioned a relay.

I'm guessing the relay on the fact he mentioned it was in the circuit and that it would probably be the easiest place to start. Where exactly is this relay? How hard is it to get to?

Any other ideas as to the problem would be greatly appreciated.

JT, I'll give your tip a shot, it sure can't hurt. How long should I leave the battery disconnected?
BubbleHead said:
....I'll give your tip a shot, it sure can't hurt. How long should I leave the battery disconnected?

Man Tim, If your compressor isn't even turning on, I'm not sure the battery trick will work. I did mine for a couple of minutes......
The battery disconnect is used to reset the climate control head, to disregard the code.
I do not concur with the theory on the bad relay, or the like. If the code 9 is set, it will NOT allow any voltage to the AC compressor, as a failsafe to prevent damage.
You should follow JT on this and perform the reset BEFORE you continue diagnosis.
Please keep us posted, c4c5
Trust Us!


It is as simple as disconnecting the battery--honest. See the prior post that says AC Help on a 90. The 90 and your car use the same type of auto climate control.
Can anyone tell me how to pull a code from the control unit?
Process for retrieval of codes

Hi there,
Push and hold the fan up, and fan down buttons, until a number is displayed, this will be your code.
Let us know what you have c4c5
OK, I went out and checked my codes. I found this page, http://www.idavette.net/tech/c4diag.htm that has some details on checking codes and what they mean.

I have a code 9, low freon detect. So, if this is what is keeping my compressor from engaging, then all I should need is to recharge the system, right?

Would it be safe to assume that an 8 year old car would leak a little and that 8 years is enough time to leak enough freon to cause this? Or should I put some dye in and look for a leak?
One last time


The control panel is confirming what we have already been telling you. Is is normal to leak freon over a period of 8 years---yes. It can leak from a failure in one of the metal housings in the system, o-ring seals, and the front seal of the compressor.

First of all, at least entertain me by doing the battery thing. If that does not re-energize it, please let us know.

Second, take a long careful visual inspection of the a/c system. Trace all the soft and hard lines. Look at the bottom side of your hood just above the a/c clutch for a build up of oil/dirt. You are looking for any area that has an excessive amount of black oil/dirt build up. Chances are, that is your leak. You may need to reset the computer, degrease all the lines spottless, then drive the car for a few thousand miles. Keep checking the lines. You will see where the leak is without introducing the leak detector to the system.

If you have done all above and can't find a leak, but the system still drops--you may have a leak in the evaporator box in the dash, or the condensor by the radiator. At this point you will need to see a QAULIFIED a/c shop. How do you know they are qualified? I would quiz them about the battery disconnect trick. If they know about that, they might just know another thing or two. They will need to use a leak sniffer to check around the other places for a leak. Once found, it can be replaced/fixed and you are back in business.

I would only introduce the leak detector chemical if all else fails. There is no need to have additional chemicals in the a/c system. The cleaner the better.
I know you guys were telling me it was probably a low freon error. I just needed to check plus, I learned something new from being able to do it myself. I hope I didn't offend anyone.

I haven't had a chance to do the battery trick yet. I could only sneak out of work this morning long enough to check the codes. I finally have some free time and will disconnect the battery after I'm done typing.

I'll also search for any oil leaks. I found a decent website about tracking down a leak and it said the same things you did. Always nice to have a second, matching opinion.
No offense

Hey, no offense, it is just that we can't help you much until you give that a try.

BTW-I highly suggest getting a factory G.M. service manual for your car. You won't believe how helpful it can be in times like this. After you figure out how to navigate through the pages, it will lead you to almost any answer you crave. You will be teaching us a thing or two about these cars before you know it.
I did the battery disconnect and it worked like you all had said. The compressor's clutch cycled after I started it up. Now, I need to take it back for the shop to continue looking at the system. I already paid them so, I hope they will finish what they started with no additional fees.

I'll keep you guys posted. You all have been a tremendous help. :D
Well, that problem is solved. I'm going back in this afternoon to see if I have a leak in the system. I couldn't find any tale tell signs of an oil leak from the AC lines.

If I have a leak, I want them to find it so I can fix it myself.

Thanmks again everyone! :upthumbs
No leaks found :D

I went ahead and had them convert my AC over to 134a so, I now have COLD AC! Thank God, the weather has gotten brutal. I could barely touch my steering wheel, it was sooo freakin' HOT!

And it's NOT a dry heat.

Again, thanks for everything guys! :D

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors


MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Advertise with the Corvette Action Center!

Double Your Chances!

Our Partners

Top Bottom