On my 1980 V6 229 AT the AC was converted to R134 a few years ago and has worked fine. It stopped working, so I checked the fluid and recharged it, gauge in the green, still not working. Checking further I found the AC clutch was not engaging. I tried shorting the connector on the low side cut out and the clutch engaged and compressor spun up. So, I replaced the sensor with a new one and the problem is the same. I checked the resistance across the terminals of the cut out sensor and it was infinite - that is the switch was open and should have been closed - fluid level pressure still showed in the green. Also, when running with the connector shorted the air coming from the vents was still warm - outside temp ~ 80f.

Any ideas on where to go next really appreciated.

Thanks,

Tony

 

Can you get a set of gauges connected to the high and low side, see how the pressure is changing when the compressor kicks on? If no change, sounds like a bad compressor.

 

I may give up and take to my local garage. I'll report back when I, or they, figure it out. Thanks.