I've had a slow leak on my system, though when I've had it looked at, they say they can't find a leak. So each spring I put in about two canisters and I'm good to go till next year. This season when I went to add refrigerant, I see that I have zero pressure high and low and the compressor isn't turning on. Tracing back, I found that the "A/C clutch cycling pressure switch" (the one on the accumulator) isn't switching on, which prevents the compressor from turning on. Is this because I have zero pressure, or is the switch bad? I shorted out the compressor and the high side only goes up to 50psi. Is that because there is no coolant in the sytem?

 

The AC Cycling switch cannot energize the compressor clutch unless it sees at least 45 psi.

Normally, the pressure from the can of refrigerant is more than enough to close the switch, unless your fill adaptor is not properly passing pressure.

Steve

 

Thanks. It seems the cheapo (read crapo) cheap gauge set from Autozone is too restrictive. I went back to my old fill hose and it fired right back up. I'll just wait till the set from harbor frieght goes on sale and pick it up there. One further question though. When reading the pressures, should they be read while the compressor is engaged or not?

 

Both. The compressor will cycle on and off accordingly depending on ambient temps, so just read the pressures whether the compressor is running or not.