AC compressor won't stay on

I have a 92 LeSabre. A/C was intermittant and I thought it might be a switching problem. While it the shop for tranmission flush, they said it just needed refridgerant.

I took a shot and added some R12. I had to bypass the low pressure switch to get it to accept the R12. That done - it began to cool reasonable well for a few minutes. However, after a while the compressor seemed to quit engaging again, and now it won't run or cool - even with the low pressure switch bypassed.

What other switches should I look at? Could it be a compressor problem?

Also, is this a good A/C system candidate for converstion to R134a?

Thanks,

Mark

More than likely, your 16-year old compressor is approaching the last days of its life. When this happens the system will get clogged from debris and block flow through the expansion valve (orifice screen). If this is the case, the high-side pressure switch on the compressor will shut down the compressor. If you do a conversion to 134a, you should suck down the system, do a complete flush and install a new compressor, expansion valve and accumulator and then pull a vacuum and charge with new refrigerant. BTW, have the system pressure tested first!