SuperStock
Well-Known Member
What's this switch for? Why didnt it connect to any wire?
What is this switch?
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SuperStock
Well-Known Member
A/C is not working. Al thought there is no freon in the system, the clutch still engage when I turn A/C on.
Im gonna replace all o-ring and gasket and re-charge the system. Is it ok to run without A/C low pressure switch?
67Dart273
Well-Known Member
So long as you "know" it's charged. This should be a plug in deal with the harness, is the wiring hacked? Engine swap?
What year model best fits the installation?
Here's a representative diagram from 72. These are not in section 8 (electrical) but rather section 24, heaters and A/C
What year model best fits the installation?
Here's a representative diagram from 72. These are not in section 8 (electrical) but rather section 24, heaters and A/C
I think it is just there to plug the hole. Usually, the high pressure switch is wired to the power steering pump in later cars. It is there to cut the AC compressor out when the power steering pressure spikes such as during tight parking and the like, to make sure the engine does not die. On your car though, there is no provision on the pump for the AC switch to get the signal. Manufacturers did not start that until the mid to late 80s, I believe.
SuperStock
Well-Known Member
Thank for the diagram, appreciate it. I think I know the problem now.
Found C2A-18DBL hang around the alternator, plug it into the A/C compressor wire: the clutch engaged. That mean I just by-pass the AC low pressure switch. The C2A-18DBL should go to the AC low pressure switch, and another wire go from switch to compressor.
Im gonna replace all o-ring and gasket, who sale these gasket set? I keep the R12, if that make a different.
The car is a restored 72 GTX.
Found C2A-18DBL hang around the alternator, plug it into the A/C compressor wire: the clutch engaged. That mean I just by-pass the AC low pressure switch. The C2A-18DBL should go to the AC low pressure switch, and another wire go from switch to compressor.
Im gonna replace all o-ring and gasket, who sale these gasket set? I keep the R12, if that make a different.
The car is a restored 72 GTX.
67Dart273
Well-Known Member
I'm nearly out of the loop on AC, I'd have to "get on" the www and search like everybody else. Perhaps others know. If at all possible, I'd switch to R134, since you need gaskets and parts anyhow.
On the other hand, LOL, I've still got a "stash" of 12 from the old days. But if I was to put a (knee knocker) in my Dart, I'd go with 134
On the other hand, LOL, I've still got a "stash" of 12 from the old days. But if I was to put a (knee knocker) in my Dart, I'd go with 134
If you have enough r12 refrigerant to charge the system I would use it but know if it leaks
it's like losing gold! To properly change an r12 system to 134a you need to remove the oil
From the system
and replace with ester oil The two oils are not compatible.
it's like losing gold! To properly change an r12 system to 134a you need to remove the oil
From the system
and replace with ester oil The two oils are not compatible.
67Dart273
Well-Known Member
WOW lot's of great stuff on that site
65PlumCrzy
Well-Known Member
Usually a pressure switch on the high side is there to kill the compressor if the pressure gets to high, to keep from having the system explode.
67Dart273
Well-Known Member
I realize this. However, that is not what these are. Ma calls them a "low pressure cutoff." Evidently if the static pressure, "shut off" in the system trips the switch, that then keeps the system off
Pete in NH
Well-Known Member
If the static pressure is below 35-40 pounds the low pressure cut off switch is meant to keep the compressor clutch from engaging. The fact that someone rewired things to bypass it is not a good thing. The Chrysler RV-2 compressor has an internal oil pump and oil supply system so, it will survive a while although refrigerant is used to carry oil to the reed valves. Modern axial compressors depend on the refrigerant to carry oil to lubricate the compressor, no refrigerant is almost instant death for the compressor.
If you have enough R-12, I would use it. R-12 is what the system was designed for and will give the best cooling performance. If you want to leak test the system you can charge it will a small amount of R-134A. Use just enough to pressurize the system with 35-40 pounds of static pressure, don't run the compressor. Then use an electronic leak detector to sniff around the system. If there are no leaks, recover the R-134A and charge into a deep vacuum with R-12
If you want to go with R-134A that's whole other story involving flushing the system out changing the oil type and replacing seals and O rings. In any event if the system has been down and possibly open to the atmosphere you will need to change the receiver-dryer. That's the cylinder that has the low pressure switch on it.
If you have enough R-12, I would use it. R-12 is what the system was designed for and will give the best cooling performance. If you want to leak test the system you can charge it will a small amount of R-134A. Use just enough to pressurize the system with 35-40 pounds of static pressure, don't run the compressor. Then use an electronic leak detector to sniff around the system. If there are no leaks, recover the R-134A and charge into a deep vacuum with R-12
If you want to go with R-134A that's whole other story involving flushing the system out changing the oil type and replacing seals and O rings. In any event if the system has been down and possibly open to the atmosphere you will need to change the receiver-dryer. That's the cylinder that has the low pressure switch on it.
tarvin890
tarvin890
A FSM comes in handy on these questions, do you have one?
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