Automotive Air Conditioning Information Forum (Archives)

Provided by

We've updated our forums!
Click here to visit the new forum

Archive Home

Search Auto AC Forum Archives

ac only works when car is warmed up

herry08 on Wed June 11, 2008 6:04 PM User is offline

Year: 2002
Make: nissan
Model: sentra
Engine Size: 1.8l
Refrigerant Type: 134a

My ac starting acting up a few days ago. The compressor clutch would click on and off very fast like it couldn't decide what to do. It is at a very credible shop right now. I called him awhile ago and he said he was very puzzled. He said all the readings are normal and he know for sure the compressor is good. He also listed several other parts that he had deemed in good shape. He said in the morning he would check all the wiring and some sort of valve that starts with a p. It consisted of three letters starting with a p. He said if it wasn't either of those he was stumped. Also said this model could not be hooked up to diagnostics. Any ideas would be greatly appreciated.

He also said the ac works fine after the car has been ran for awhile.
2002 nissan sentra 1.8l

Chick on Wed June 11, 2008 6:57 PM User is offlineView users profile

Check the clutch gap, should be .02 or there abouts, make sure it is recovered and recharged to system weight, As the engine warms the pressures rise, could be low charge, not sure what the P valve is though..Hope this helps..

Email: Chick


Freedoms just another word for nothing left to lose

mk378 on Wed June 11, 2008 7:04 PM User is offline

If it happens only at idle, it's not an A/C problem exactly, the engine is not running properly. When the compressor comes on it is an additional load and it abnormally slows down. The engine computer detects that it is about to stall and shuts down the compressor. Then the engine speeds up a little and the computer turns the compressor back on; the same cycle happens over and over again.

This only applies if you can rev up the engine a little with the gas pedal and have the A/C work normally.

herry08 on Thu June 12, 2008 1:21 PM User is offline

went back to the shop today. the mechanic checked all the wiring and it was good. he even got the nissan dealer to let him "borrow" new parts to rule things out. also, one of the nissan techs came down and was also puzzled. he even hooked up another new compressor and it was also doing the same thing. he vacuumed and recharged the system and all pressures were still normal. when i got there he had the compressor jumpered and it was running fine, ice cold. He says the ac system is fine and is 90% sure its the computer. a new one is $600. he is looking for a used one now. anyone ever come across this problem? i really trust this guy and he swears everything else is in perfect operation.

mk378 on Thu June 12, 2008 2:02 PM User is offline

It does it all the time, not just at idle then? Is the check engine light on? Does the check engine light work? You can scan any post-1996 model car computer for basic trouble codes with a generic OBDII scanner.

Edited: Thu June 12, 2008 at 2:03 PM by mk378

herry08 on Sun June 15, 2008 3:21 PM User is offline

got the car back and still no luck. The check engine light does work but is not on. if the car is in park the compressor runs all the time. when you put it in gear it kicks off. when cruising down the road it kick on off on off so fast it feels like the car is missing. like i said the engine light is not on and the car runs as smooth as can be. i just don't get it. when it does work it is cool.

Back to Automotive Air Conditioning Forum

We've updated our forums!
Click here to visit the new forum

Archive Home

Copyright © 2016 Arizona Mobile Air Inc.