Automotive Air Conditioning Information Forum (Archives)

mazda626awd on Fri September 07, 2012 12:36 PM

Year: 1991
Make: Nissan
Model: Pathfinder XE 2WD
Engine Size: 3.0
Refrigerant Type: R12
Ambient Temp: na
Pressure Low: na
Pressure High: na
Country of Origin: United States

I've been troubleshooting an intermittant A/C on this vehicle. I was concerned when reading out the wires and found that 12 volts goes into the ECCS but only 9 volts comes out. I thought that the voltage drop was going to be too low to energize the ac relay. But after deeper research, this is normal. My other concern was when reading continuity through the AC switch to ground I had a pretty high resistance. Keeping in mind that this does also read back through the fan switch, it might be normal. The book gives no value on it. Now that brings me to the Temp control amp located on the evaporator box. It has 3 wires, 1) power source, 2) the wire going to the fan switch, & 3) the other wire or the amp switching wire. I know this input is the core temp and that it some how is capable of switching on and off the compressor. At any place on this control circuit, I can ground it and things work normal but bypassing the AC switch. I have located all but one body ground and confirmed a good reading. When the system was working normally one day I was able to get a set of gauges on it and it did need a few ozs. It used to come on when started and than kick off after any time between 14 to 45 minutes, or it could work normally all day long. After the service it hasn't come on only briefly or not at all. I have verified all the wiring and both the AC and Fan relays. I also verified the dual pressure switch both before and after the servicing. I just can't get past this amp. The dealer doesn't carry it anymore and the only place I've found it online it sells for $450. It seems they were used in 89-93 pathfinders, but I really would like to confirm the problem before I buy a new or used one. The other question I have is how to remove the amp. Does the system need to be evacuated? The book give no clue. How can I bypass this? I tried jumping the source wire to the fan switch wire but that did nothing.