A/C Question

[Gene]

Just got my compressor back on after installing headers awhile back, and I had my sisters b/f come over to charge the system back with Freeze 12(R12 replacement). Anyways, he noticed with the system empty of freon that the compressor clutch stays engaged even though the system is bone dry. Now, I know absolutely nothing about A/C systems but he says is should be cycling on and off constantly with no freon in it. Now, I had to bypass the switch on the A/C door that sends power to the clutch because my switch was bad, all I did was put a toggle switch inline to send power to the clutch, my question is, what tells the compressor to cycle on and off? I mean I see no other switches that send power to the compressor other than this one and when it is set on A/C it is always sending power to the clutch? Thanks in advance guys, I know you can help me figgure it out

[FirstGen]

There should be a hi/low pressure switch mounted to one of the lines or on the dryer/reciever. It senses if the pressure is too high or too low (your case). I don't know where it would be on your truck however.
Good luck.

[extd56]

I was told by an A/C guy that our year trucks do not have a switch in them and they will run as long as the air is on. He also said that they will also run when they have no freon in them, not a good deal. I believe you can install a switch for low freon but not sure.

[kelsfine69]

It would be a good idea to install that low pressure cutout switch. On the other hand if it ever stopped blowing cold air , just make sure to shut it off.
My 2 cents

[BobbyK]

the orig R-12 systems were designed to run continuously.The TXV and POA will prevent evap. core frreeze-up.
The orig. compressors take about 12hp to run and having them cycle on and off via a low preassure cutoff switch will not benefit the system.

[Gene]

Thanks Bobby, thats what I was thinking. When I had my system up and running before I dont remember the clutch cycling at all.