I have a 1993 lt1 Corvette. Have had some issues with a/c not working. Was serviced. I found the upper two wire switch loose and thought the Freon leaked out as to why it was not working and also replaced switch as the plastic threads were stripped. I assumed system was empty so I installed Freon without checking pressures. When I installed Freon it was only 54 degrees outside, so I jumped the two wires to get the compressor clutch to work and take 36 Oz of Freon. Car continued to work fine but had not used the a/c. Last Saturday it was warm and decided to turn it on and immediately the asr/abs lights came on , engine stumbled, stalled was able to start at first but when it did I made it to an empty part of parking lot. Disconnected a/c connectors. Checked ecm codes had code 68. That was probably from disconnecting wires. Tried checking other codes (A+G) could not get to the asr codes 9.0 finally did and nothing at 9.7. have no power now trying to start for fuel pump, no power for radio, windows, seats. Take fob away, car begins honking continuously and have to disconnect battery. Stumped!

 

talk about some strange events.

Code 68 is related to the AC relay.

I am just not sure what is causing this... I will have to think about this one.

 

I read this thread a few hrs ago and decided to wait till someone else deciphered it so maybe then I could understand....Still don't understand!

I was pretty sure I missed sumthin ! Now, I'm positive !

 

All I know the car was running good until I turned the air on. I will check the relay which I assume is the relay on right inner fender well along side the transmission 1-3 shift. About a month ago I replaced both of those as they had been open to the weather with hood off sitting outside while the neighbor was replacing the engine.

 

Sounds like the AC system is way overcharged.

And it sounds like you have blown a fuse or a fusible link.

 

I think you need to take a step back and regroup. Firstly a shorted relay is extremely rare (The ECM thinks the relay is closed because of voltage on the sense line when there should be none) . But the worst thing that should happen is the compressor will always be running. If the compressor came on with an A/C request, then the relay is probably OK. I would clear all the codes and recheck at a later time.

Forget the A/C for now. As said you need to get all basic systems working again. Check fuses and all 2 boxes of fuse links. How do you know the fuel pump is not running. Is it because you don’t hear the 2 second prime?

If you get the car running, you need to get a set of gauges on it. But that won't tell you if there is too much Freon in the system unless the high side or head pressure is excessively high. The actual correct thing to do is to have a A/C repair shop evacuate the system. They can measure how much came out. The they can refill with the correct amount.
BTW - It is not advisable to service the A/C at 54 degrees. You should really be up toward 70* where things can work more normal, compressor will cycle correctly and pressures will be more at the more normal operating pressures.

 

Will get the car down to the neighbors so he can evacuate the Freon. I'll check the relay. I do have a question on the relay. The original ones that came with the car were both the same part number, but when I replaced one for the a/c was a 5 pin even though there is only four wires and the other one for the transmission 1-3 locketout is a four pin, neighbor says the four pin will work for the a/c which would be like what the car had in it when I bought it in '08. I could not hear the fuel pump run up.