Automotive Air Conditioning Information Forum

Success.

After doing more homework I found that the replacement ACC (air conditioning controller) which was a field replacement for a rash of failed controllers. Finding the literature for that states the original thermistor to be left in place, and to drill a small hole in the access panel and ...

I'd be tempted to just leave the troublesome one out of the picture and see what happens.

Thermistors are used in resi AC to help the controller that runs the variable speed fan motors (which is a hoax). These thermistors are constantly burning up, costing homeowners major bucks


That's what I ...

Yes. I had a list of the pressure specs and had incorrectly assumed the in compressor TEMP sensor was a LPCO switch. The specs say LP and HP cut off but only looking on another page did it show those numbers were for a binary switch, installed in the R/D. Which never sees low pressure.

The LP ...

That's the million dollar question. The service manual (online) shows a thermistor with yellow/yellow Red wire as the evap sensor. This was the one installed in the factory entry into the evap case, which at present doesn't do anything.

On top of the evap case is the AC Controller. Which is plugged ...

Making headway.

I opened the evap housing access hatch and removed the thermistor wires. There was ample wire in the harness to pull it down and out. Put my temp probe for my Fluke in the evap core. Temp probe in the center vent and gauges hooked up.

10 min run time
Ambient 75*f
Engine 1500 rpm ...

Think I may have an idea.

There is no LP cutoff switch. What I thought to be the LP cutoff switch is a refrigerant temp sensor in the compressor. The dual pressure switch (mounted on R/D only sees high side pressure and the specs for that are ON 28 +/-2 psi / OFF 428 psi (converted from Kpa).

I ...

'LP side at idle will hover 27-28 psi.'
What is wrong with that?

Don't know how much looser you can go. Be sure tension remains on the spring else it is going to come apart while operating...


The Low pressure switch cuts off at 28 psi. Clutch on off cycle is 10 seconds. Vent temps fluctuate ...

Had a chance to work on the Montero. Pulled the evap housing out, and turned the set screw 2 turns CCW.

I'm making headway, but problem continues. LP side at idle will hover 27-28 psi. Previous was high teens. I researched and found the low pressure switch numbers in the service manual. LP cutoff ...

How did you top off the system? Did you evacuate and recharge a known weight or did you use a can with the gauge?

Add a mister system to the front of the condenser. Use distilled water and a half dozen mister nozzles.