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Pathfinder intermittant A/C

mazda626awd on Thu June 27, 2013 1:33 PM User is offline

Year: 1991
Make: Pathfinder
Model: XE
Engine Size: 3.0
Refrigerant Type: R12
Country of Origin: United States

My 91 Pathfinder has an intermittant A/C problem. I started troubleshooting it last year and while it was working, had the local service station check the charge. It only needed very little freon and pressures were said to be perfect. When I first start it, it'll work great any where from 5 min. to 30 min. But the first time the compressor cycles, it'll not reengage. Some times if I shut the engine down and immediately restart, it could be fine. I replaced the AC relay, which seemed to help for about 30 min. but then it kicked off. At that time I only ran it with outside air. The OAT was 93, vent temp with outside air was 57. With inside air recircuating it'll get down to 47. My previous troubleshooting revealed that the power going into the ECCM was 12 volts but came out around 9 volts. When I check the voltage at the relay it is around 11.5 with 12 volts on the clutch side of the relay. The dual pressure switch reads OK when it is in the intermittant off condition. The other electrical component in the system beside the switch and clutch is the thermo control amp. It has 3 wires and I can not find any troubleshooting info on it. The book says it provides protection from freeze up. The amp is no longer available and have found it in the past on flea bay for over $400. Anyone have any ideas or comments?
Dave in VA.

94RX-7 on Thu June 27, 2013 2:54 PM User is offline

Did you test for voltage at the clutch when it should be running? It isn't clear from your post if you tested at that connector or not.

If you have voltage at the clutch it may be that your clutch gap is too wide, and it can't pull in reliably. Turn it on, then tap the clutch hub with a wooden hammer handle or something similar and see if it pulls in and runs.

mazda626awd on Thu June 27, 2013 3:04 PM User is offline

94rx-7, I checked the voltage on the clutch side of the relay but not at the clutch itself. I will do that. How would the clutch gap change if nothing has been done to the system. And it seems most of the time if I shut off the engine and start it back up, the clutch engages. That voltage has its own source. I'm somewhat concerned about the loss of voltage going through the ECCM since that is the side where the control is being exercised. I'm also leary of that thermo control amp. Thanks for the response, I'll be checking out the clutch voltage in case there is a loss between the relay and it. Also I'll be able to check the pressures when I can get the adapters I need to tap into the high side.

Dave in VA.

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