I just finished reworking my 95.5 Rodeo A/C system for a trip I'm taking the family on tomorrow, and temperatures are pretty hot now, so A/C is a must...

Old compressor blew the front seal. The only reasonable reman compressor I could find around town today didn't have the temperature switch on the compressor to cut out the clutch at high temp.

(Horrible job, I had to run all over town to find a new reciever / dryer. One that I found didn't have the shipping plugs installed, the parts guy didn't see anything wrong with that <img src="/forums/images/graemlins/scared.gif" alt="" /> (hello, humidity in the air ruins the dessicant bag...) The parts guy where I bought the compressor insisted it was filled with oil. I only drained about 10 cc of oil out of it, if that. So I got a can of PAG oil and refilled the compressor, condensor, and dryer in accordance with the factory manual. (what is the correct viscosity for the PAG oil in a DKV-14D Zexel compressor anyway? Castrol and Johnson Lubricants show 150 visco for this compressor, which is what I used, but other literature I have on double vane type compressors claim to only use 46 visco PAG...

Anyway, replaced the compressor, flushed everything else really well (took the condensor out of the truck for the flush... it actually wasn't that dirty), drew a really good and deep vacuum with a rented pump, and added new refrigerant...too much at first (I was shooting for under 23 ounces (system takes 22.8 oz) with two 12 oz cans, and a bit of liquid slosh in the final can left should be just about 23 ounces. Anyway, wasn't paying attention and added nearly all 24 ounces and high side gauge started reading too high (going right for that 350 pressure switch cut out limit). Easy solution is to put the can (still connected to the gauge set) in a pan of icewater to chill it, then bleed some from the system (a squirt from the high side, with the system off of course and the pressure below 150 psig) Anyway, a couple of squirts back out of the system, let it stabilize, then ran it for a while and the pressures were not back down in the acceptable range and the bubbles in the sight glass on the dryer look perfect.

So this missing temperature switch... does it perform a vital safety role for the system? (But the pressure switch does that...) What does it do, and is there anyting I can do while operating the system and vehicle that can compensate for the lack of this switch? The system is running perfectly right now...

Thanks

The pressure switch will cut the compressor off if the pressures get too high or too low. The temperature switch should cut the compressor off if the temperature gets too low so that you don't start freezing the lines.

Richard <img src="/forums/images/graemlins/patriot.gif" alt="" />

all i can tell you is that the circuit schematic in my helms manuals FOR A 1992 TROOPER with 3.2l sohc engine, says the

A/C THERMO SENSOR
Closed 145* +/-5*C (293* +/-9*F)
Open 160* +/-5*C (320* +/-9*F)

which says to me that it cuts off the compressor when it's open, which is when the sensor senses the compressor has temps above 311*F to 329*F. search for a JLEMOND post fairly recently where he gives some info, i think.

i don't know what the chances are of this sensor actually needing to do its job. but, my guess is, it has some safety implications (or parts preservation function).

can't you just use the old sensor/switch? i don't know for sure, but i'd be surprised if the a/c compressor relay would function without input from the thermo sensor/swith.

have a good trip. . .

Thanks trooperbc! So the temp switch opens the contacts and kills the compressor clutch at high temperature, above 320 F, which actually is screaming hot for R-134A. It must do that so it doesn't overpressurize and blow out the line between the compressor and condensor, as the pressure switch on the dryer is located after refridgerant is pumped through the condensor and pressure could be lower there.

I couldn't reuse the old switch, as the new compressor has a pressed in plug where the switch resides.

Just got back from my trip, and the A/C ran like a champ.