I just tried my a/c yesterday for the first time in about 6 months and it didn't work. Thinking that I was low on R12, connected my 15lb bottle to the suction side while sitting in a bucket of hot water.
Next I started the engine and turned the air on, the clutch would not pull in. Connected two wires from the battery to the clutch connection and it pulled in.
Today I checked it out with my multimeter and found that the pressure switch was in the closed position. The connector going to the clutch connection was putting out 11.97 volts with the key on and engine off. The battery was showing 12.30 volts.
Next I started the engine and measured 14.09 volts at the clutch connection and 14.3 volts at the battery.
This time when I connected the connector to the clutch it pulled in.
So I stopped the engine and restarted it with the a/c working.
After all this I think I have a bad connection?
Where have you guys found problems with the wiring in regards to the clutch?

 

When my air conditioner became intermittent, I found it was the cycling switch, buried deep inside is a tiny dip relay that finally gave up, mine gave out while on a road trip through San Bernardino when it was 100+* outside and the family inside, I pulled off into a Home Depot parking lot and diagnosed the problem, within about 15 minuets with enough spare parts I carried in the truck I had installed a relay to bypass the cycling switch and we were back on the road.



The switch is mounted to the H-valve; here is my article on it.

https://www.dieseltruckresource.com/...h-t112028.html

Are you still in Glendale?

Jim

 

Jim,
I still live in Glendale.
I have a used cycling switch that I will install without putting the probe in the suction line and see if the compressor clutch works. If the switch does work,
I will install the probe in the suction well and start adjusting depth for temperature.

 

I just checked the a/c with the old and used switch and they both work.
So I will keep the old switch installed and when the clutch will not pull in I will connect the used one to verify the problem.
The evaporator temperature at idle is putting out 40 degree air.
Thanks for the help Jim.
P.S. I still wonder in the back of my mind if it is a wire connection problem.

 

Hey Bruce, try turning on the ac, make sure the clutch is turning and start wriggling around wires and connectors. It's low tech but effective...Mark