QuestionQUESTION: Roland,
Caught your answer to the one question about the intermittent A C and using the defrost control button and to self diagnosis. Unfortunately did not work on my car. I have the same problems would you have any other advice.
Things I had done.
Checked both fans circuits and relays with OTC scan tool. Added some freon. And pulled a lot of hair out.
ANSWER: Hi Paul,
Usually intermittent operation would most likely be that the level of refrigerant is marginal. How much R-134a did you put in, and how does that compare to the maximum amount that is needed as shown on the sticker located on the under side of the hood? How long prior to adding the refrigerant had it been since the system was last filled and operated?
So depending upon the answers to the above questions you may either need to add more refrigerant or seek to determine the pressure in the system at present to understand exactly where you stand as regards the level of refrigerant.
Does your OTC reader show any fault codes within the powertrain?
Please 'rate' my answer, and consider a 'nomination' of me (see the PS below).
Thanks,
Roland
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QUESTION: That was my thought, so I put in about 1/2 a can. All was good, sent them down the road. But they said it didn't change. Sometimes it would work/ not work. I noticed on the second visit that the AC did not come on at all and that the aux. fans weren't working. I did a physical relay check of operation and verified both were good as was the fans, (OTS scanner test for hi and low fans I found while checking codes. No codes by the way# everything except what was the trigger for the relays to turn on the fans. The sticker says 22.5 oz of R-134. No service to the AC system from time of purchase #original owner).
Right now the high side reads 165 psi and the low side is 24 psi.
I did a power cut from the battery for 30 min. at room temp. and that brought the system back on line, thought all was good to go. After the car set for 30 to 60 min. back to the fan and AC non op status.
Then I tried your defrost sequence but I got no response from the light but the fans and AC came back!?
It's sitting right now, will check shortly. But I still don't know what is wrong and want to figure it out.
I just tried it and it was back to non-op status. But, I played around with the defrost button and at first it didn't turn on the defroster and then it did come on. And so did the fans and AC! Interesting.
Paul
When the compressor is running with fans on the low side is 24 psi and the high side is 165 psi. currently.
I put about 1/3 to 1/2 a can which was my first mistake. Don't know how to determine what was in at the time when I added. But the sticker said 22.5 oz.
ANSWER: When you measure the high side pressure, you also need to know the temperature of the liquid line to decide if the system is undercharged, correctly charged, or overcharged. Do you have a thermocouple to do that measurement? If not, then that would be the next thing to do. Attach the probe as near as you can to the condenser outlet.
Thanks for the ratings/nominations.
Roland
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QUESTION: 3 Readings as you instructed
1. low side = 26 psi. high side = 170 psi. Temp. 83 degrees F
2. low side = 25 psi. high side = 165 psi. Temp. 84
3. 25 165 84
AnswerHi Paul,
According to the graph you are just slightly outside the proper charge range, on the overcharged side. At that temp the proper pressure should be between 130 and 160 psi, which is not far off from where you are. But that could explain why you are getting intermittent function. I wonder whether it would be worthwhile to draw out some refrigerant (less than 2 oz), or just live with the situation until through normal slight leakage losses it moves into the proper region. I don't have experience sufficient to advise you one way or the other, but you are close to the proper charge level. I also am not certain that being this close to the proper range would in and of itself be the cause for intermittency, but I can't ID another reason without a fault code. You might do well to measure the voltage on the pressure transducer when it refuses to run by measure between the wires on pins 1 and 3 of its plug (black/light blue and dark blue wires).
Roland
PS Thanks so much for the nominations which you are entitled to do again if you would like.
