cdemsky

I have located this Low Pressure switch screwed into the top of the A/C Drier (2 prong connection), and it is screwed (threaded) into the Drier. My question is can I simply unscrew the OEM and replace without Evacuating the refrigerant (R12) from the system or is it a requirement in replacing this switch? The Factory Manual does not specify. I have been told by a Gen. 2 RX7 person that on those cars it was not necessary to evacuate coolant before replacing that switch, but he was not certain if that was the case in the 1st. Gen. cars.

TIA
Chris D.

GSLSEforme

1) It’s in hi pressure side of system= hi pressure switch
2) Yes,you have to evacuate system to change switch,switch has to be exposed to pressure to function. Not sure where that tidbit of info where unnecessary to evacuate 2nd gen to change switch came from,not accurate.
3) Have you tested switch on drier? It should show continuity with a charge of refrigerant in system. They don’t fail often.
Is compressor clutch not engaging?

cdemsky

Yes, the Clutch is not engaging that I can hear, unless it is exceptionally quiet compared to other vehicles I hear clicking on and off. It has been too many years since I had my first '85 RX7 to remember, I sold the car in 1998 with only 38,000 miles on it. I honestly can't remember if I could hear that A/C clutch kick on and off or not. I will check the switch for continuity. I will also clean the 2 prongs and the wiring harness that connects to it with Electric Cleaner I have. I have found this to fix many things that appeared to be not functioning any longer, I am assuming due to environmental buildup on the connections masking them from making adequate current flow.

When I first got the car the A/C light on the dash controls would not come on. Upon inspection I found the Fuse was blown for it, so I replaced it and the switch light comes on now. I would think you should be able to both hear and perhaps even feel when the clutch/compressor starts cycling, and this does not.

rxtasy3

iTrader: (2)

every a/c equipped car i've ever had u could hear the a/c clutch engage. u should be able to jumper the two wire connector and the clutch should engage.

cdemsky

Thanks Michael, I had forgotten that I did that years ago on both a Dodge Ramcharger and later on a Jeep Cherokee.

GSLSEforme

I would put gauges on it and check static charge of system. The low pressure switch on suction(low side) of system will not allow compressor clutch to engage if refrigerant is too low to keep compressor from being damaged from lack of lubricant.
You can test it by turning key on,ac switch on and fan on any speed. If enough refrigerant you will hear compressor clutch magnet engage clutch and you should not be able to turn compressor by hand.

You can jumper the low pressure switch connector and see/hear clutch engage without running engine. Likely if no refrigerant there will not be enough lubricant in system. Gauge readings will also tell you this without running engine. My money is low/no refrigerant.

The hi pressure switch in drier on high side(discharge) of system is there to prevent excessive head pressure from damaging compressor either from overcharging,hi side blockage and or defective cooling fan clutch.