Thermistor?? vs 1700$

A thermistor changes resistance as its temperature changes. They've been part of electronics forever. I could buy a variety of them in all shapes, sizes and values for pennies each. It's very conceivable that a thermistor could be responsible for temperature feedback to the ODBII. Maybe even replacing such a thing as a pressure cycling switch which tells the ODBII the temperature by the pressure of the refrigerant inside the evaporator.

Could it be that the Coolant pressure is on the low side causing the high pressure sensor to shutdown the AC compressor. This would account for the intermittent operation. Also have heard a of bad high pressure sensor switch that has same symptoms. You may want to measure the switch resistance when AC is running OK, and when not. If resistance is same, the problem is somewhere else.

Not related to your problem, technically speaking, but why would you take it to Autochek or whatever without first going to the dealer from whom you originally purchased it? Even if it is inconvenient to go there, a phone call would have certainly been easy enough. You deal with Autochek and that's fine, but did you feel you had no recourse with the dealer? They fixed an AC problem originally, and now it has another, or the same AC problem again. So you go elsewhere , waste another repair shops time on what appears to be an inaccurate diagnosis, and finally do what should have been done in the first place -- call the original dealer! Now you are in a steamed state of mind, pissed at the dealer, based on the assumption that they screwed you, without even having given them the chance to correct the problem. I hope you had the decency to thank the dealer for correcting the problem.

A thermistor is an "electric thermometer". Essentially a resistor that changes it's resistance based upon temperature. Depending upon your particular thermistors location and intended function, it could theoretically "shut down" the AC partially or even altogether. AC systems do not lose and then regain their charge, so based upon your description, it is unlikely that you had a leak, but an electrical or control problem. Without a wiring diagram and possibly a diagnostic flow chart, it would be difficult to make an accurate diagnosis. Of course, the person interpreting this information is fairly important too.

I went to the dealer first and 19 year old at desk asked I bought the extended warranty and smiled blakly at me.

I then went to my salesman and in front of the other sales men who kind of looked at me like and suggested that it was probaly a relay. No help in getting it fixed there. That was when I decided to go waste the time of the AutoCheck, who I paid $25 to look at A/C. And give me a wrong diagnossis. That was when I got the manager involved. And I did thank him for taking care of the problem.

And thank you

My apologies. I made an erroneous assumption.

Rule 1: If you don't get satisfaction, go higher in the chain of command.

Rule 2: NEVER ask a salesman about repair work beyond if the sales department will cover it.

I do work in a dealership, so I have some insight into this stuff. Also makes me a bit defensive at times -- in case you hadn't noticed! :)

looks like the shop you went to made a guess and it was wrong.. like when the doctor says you need your (xyz) removed.. you get it done and dont think anything about it or you dont get it done and nothing happens.. you call back the doctor and say: hey man i am OK... what was wrong with you for telling me that my XYZ was bad and had to come out???? glad you got the a/c fixed....

maxxer wrote:

The local shop said something about low pressure. Told me the sensor was on the inside of the compressor, so the the whole compressor would have to be replaced. They told me there was a leak in the system but it wasn't low on freon because it was on the negative side. How could it be leaking and not losing something.