I just had my corvette converted from R12 to 134a. The shop vacuumed down the old r12 and pressure tested the system. The system held a vacuum and there was no major leaks at the time. The shop recommended I changed my receiver and I allowed them to. They changed the Connectors to the 134a ones and added refrigerant as well as dye. Car blew ICE cold when I drove it home from the shop. Now the air does not work and I am getting 09 Code on the HVAC for low/no freon. Once I reset the system by pulling the fuse, and reinsert it the code goes away and I have ice cold air. This happens every 30 minutes of driving. There is no freon leak. The car is not low on freon. Gauges indicate full. What is telling the car it is low on refrigerant? Any help appreciated. I don’t know what to do next. The shop specializes in A/C and they said it held perfect vacuum for 30mins.

 

It's probably low, frequency of cycling switch off indicating low. Code sets and compressor disabled.

 

I cannot for the life of me find the Low Pressure A/C switch that will fit this car. I bought one from advance auto but it would not thread on it looked identical to my old one. I’m almost certain my original one is bad. Could someone link me to the Low pressure switch that will fit a 1992?

 

Have you looked here? (Link below)

AC Low Pressure Switch

 

None of the ones on rock auto really match up with what I have in the car now. 2 wire setup. My mechanic was scratching his head. The GM part number is 52461142.

 

Aha, that makes finding it MUCH easier...and inexpensive ($6.29) too! Here you go ---> AC Clutch Switch

 

So, the 92 with R12 cycles at 25psi. The R134 systems cycle at 22.5 psi (switch). I can't say for sure if the threads on your evaporator for the switch is the same on your 92 and is on my 94. I don’t know if you can screw a 134 switch on to your 92 where there was a R12 switch. (One would think so but maybe not).

However I can give you part numbers that are for a 134 system (94-96 vette) that can be bought at any local part store. One is the Santech MT0205 and other, 36659.

You should monitor either thru a voltage or data stream the output of the high pressure sensor on the high side. If the voltages are not correct, the ECM will shut down the compressor.

Also the cycling time of the compressor is measured by the AC programmer and if the rate of frequency of cycling is not correct it can inhibit the compressor.

AC systems are not just Freon, there is a lot of electronics and software that have to be understood.

 

Thank you I think that is the part I need. I bought a Delco part from Advance auto that said it would fit a 1994 corvette (R134) but it would not thread into my 1992. But last night I unscrewed the factory switch, and it had gunk in it. I cleaned it out and dried it, I put it back on, seems to work without shutting down the compressor now. Fingers crossed.

 

Good luck Larry, hope that's all it was. Keep us updated after some time has elapsed to let us know if the fix was that easy.

 

If you connect a set of gauges to monitor the low side, you can see the cycling points of the pressures. That gives you a big clue as to what's going on.
Hard to work on AC without gauges where it handicaps you with needed information.

 

I did the swap myself and yes it is good to replace the receiver/drier whenever the system is opened for any reason. I never replaced any switches or had any issues when I did my 1988 C4. It blew cold right away and has continued to do so.

Life is always better when you have the tools you need for a specific job. AC gauges are good to have, I also have a 2 stage-vacuum pump to draw the systems down to check for leaks or re-filling the system. Air Conditioning is one area where my knowledge is a little thin. I know just enough to be dangerous.

Had to use a timing light the other day, when was the last time you used a timing light? I still have some of my Wentworth tools from OLD British Motorcycles. The scanner I purchased a couple months ago has turned out to be a very handy tool. To store the tools I might have to make my garage a two story as I like to tinker. I now have the capability to make parts from casting aluminum in my back yard and doing the machining work in my garage. A couple ATF agents descended down on me one day and when they saw my shop they wanted to know what I was making.... I think it scares them that we can actually build our own parts when needed. There were a lot of questions and none were about my Corvettes. I was plating metals in my shop for a while so my C3 has Bright Nickel parts where Chrome was normally used. Bright nickel is a harder and less porous surface than Chrome. If you can see colors (I am color blind) then you might notice a blueish tint to it I have been told.

I like tools, it is a weakness of mine......

Best regards,
Chris

 

Truer words were never spoken!

Amen to that.