2000 Nissan Frontier a/c problems


#1

I have a 2000 nissan frontier and am having a/c problems. The compressor comes on but the air is not very cold. I had it in the shop 4 times last year for this and although the freon was topped off it still is not very cold. I recently read where removing the thermistor might fix the problem. Has anyone done this and what were the results?


#2

I can’t be of much help as there is no info to work with.

System evacuated and recharged, etc.? and most importantly; knowing what the high and low side pressures are.

Maybe there is an internal problem in the dash in which a blend door is not working properly and the problem is not even related to the system charge. This will allow air to flow through the heater core; A/C on or not.

Four times in one year with the only thing being done is topping off the refrigerant points to someone not being very proficient in A/C work, assuming it’s the same shop of course.


#3

I recently read where removing the thermistor might fix the problem.

I love that kind of advice. Do you really think the manufacturer would have wasted the cost of a thermosistor if it was not necessary for some reason?

If you were low on Freon, did they check for leaks?  Your A/C does not use Freon.  If it was low it means it has a leak.  Maybe a different A/C shop would be a good idea.

#4

I found the reciepts and it was actually 3 times that I took it back. Anyway, the first time in they replaced the expansion valve, the thermal control amplifier and recharged it. It seemed to work for about 3 weeks then started not cooling again. I took the car back a second time and this time they replaced a pressure hose they said had a pin hole leak and then recharged the system. This seemed to do the trick for about 2 more weeks and then the problem came back. The third and final time I took it in they said the pressures were all good but that the hose they put on was faulty. This seemed to be the answer up until about a month ago when summer weather started to hit here in Florida. Now it is ok in the morning but not cooling down at all in the afternoon.


#5

With the repeated trips, the pinhole leak followed by the alleged “bad” new hose diagnosis, and the advice to remove the thermistor leads me to believe they’re not terribly sharp on A/C work.

The cool in the morning, not so cool in the afternoon points to the refrigerant charge probably not being what it should.
Without knowing what kind of high/low pressures are involved it’s hard for me to say.


#6

Ok. Thanks for trying. I am planning to take the truck into the dealership and bite the dollar bullet. I saw this issue brought up on the cars.com website and the owner said he remoed his thermistor and the a/c problems were resolved. I just didn’t know if it was wise to do this or not. Thanks again.


#7

Didn’t think I was going to get reprimended because of this question! Geez!


#8

Just an FYI here. The thermistor is a temp controlled probe that fits into the evaporator case and has a pair of wires. This thermistor will cut the compressor on and off depending on the evaporator temparature; basically to keep the evaporator from freezing up.

I used to work for Nissan back in the 80s and some of their models did have problematic thermistors, even on new cars. The recommended solution was to pull the probe out a bit, but I found this to not work very well. However, I did discover that the thermistor has a very tiny paint sealed adjustment screw and I cured many of them by chipping the paint off and readjusting the thermistor. This was predominantly on new cars actually.

The thermistor could be bypassed but this could lead to evaporator freezing, which means warm air and less air unless the A/C is turned off and the evap. allowed to thaw out.

My feeling is that the thermistor may not be the problem. If the air is not that cold when the compressor is engaged then it sounds like a charging problem or possibly a faulty expansion valve.
The thermistor factor would only come into play if the compressor was short cycling; basically, turning off too quick.

You might consider inserting one of those cheap A/C thermometers into a dashboard vent and while traveling on the open road, check the temp output when the compressor is engaged.
A good system should produce about a 50 degree drop (at least)in comparison to the outside temps.

I hope some of that garbage helps anyway. :slight_smile:
(Still ok4450 and CarTalk has done went and logged me out yet again.)