The air conditioning on my 1998 Legacy Wagon 2.5i suddenly stopped working. I found after eliminating the obvious causes such as low refrigerant relay, fuses etc. that the twin wire connector to what looks like a sensor on the compressor top was showing “open circuit” with my ohmmeter.

(see illustration). On jumping the connector with copper wire the air-con worked normally.

 

 

Could anyone tell me what is the function of the sensor, could I leave it as it is, or shall I replace it, I found a Subaru reference Bulletin number 10-74-02 which highlights concerns over a malfunctioning compressor revolution sensor. Is this what it is and could I do without it. No doubt it's expensive and would certainly entail a refrigerant recharge at best. Here's hoping!

 

 

When your air compressor pressure switch is faulty, the symptoms are usually freezing up of the air conditioning system, due to the compressor not turning off.

 

Heating And Air

I have exactly the same fault on my 96 Legacy OBW. That is the part. I was just at the A/C repair shop out of sheer desperation. The old school mechanic there ran current to it, effectively "jumping" it, and lo and behold!!! My compressor started running, and my air started blowing cold. Only problem is that the "fix" doesn't last if you don't keep it powered. So... I'm assuming we need it there. Where did you find yours? I've been looking online with no luck so far...

That's not a revolution sensor. I'm pretty certain that it's an thermoswitch that will kick off the compressor if it overheats. Not all models have it, either.

 

As long as you confirm the compressor is not getting too hot, I don't think bypassing it is a problem.

The small one with the black plug is the revolution sensor. The larger sensor wih the green plug is probably a thermo-switch, as presslab said. I don't know that either of those sensors is available as a replacement part.

The small one with the black plug is the revolution sensor.

 

Sure? Looks like the clutch coil to me.

The compressor in that pic is not original equipment. No 90's Legacy A/C compressor had more than one connector (or any connector that looked like those), or a "revolution sensor". The single wire is for the magnet clutch. The part with 2 wires is a thermal protection switch. 96-98 had them. If the switch is open and the compressor is not pretty hot, the switch is faulty. Just connect the two wires together and bypass the switch.

fairtax4me is right -- it's the black one I was looking at, sorry for the confusion. Does ANYONE know where I can source one??