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Air conditioning question

1K views 5 replies 3 participants last post by  rogoman 
#1 ·
I have a question about my condenser fan. Basically when moving steady like on a highway my ac blows 41-45F but idling it’s 65-75F. I changed the cabin filter it wa a dirty. Then I blew water through the radiator to make sure there wasn’t any obstructions and at idle it went and stayed at 40ish for awhile or till the water evaporated. My question is even though the condenser fan is running is It the culprit? Not being able to pull enough air through at idle to cool the cabin? Any thoughts would be greatly appreciated thank you
 
#2 ·
When the car is moving, versus stopped, there is more air flow over the condenser (the heat exchanger in front of the radiator) and that airflow is essential to system operation. To maintain airflow when the car is in stop and go traffic, or is completely stopped, condenser fans will come on automatically. If the fans don’t come on, the circumstance you have could occur. You might also have a low state of refrigerant charge; to properly diagnose an AC system, the standard Manifold gauge set needs to be used to measure both the high and low sides of the system. Other possibilities are that the compressor clutch is not cycling as intended or that the condenser might be blocked or dirty. And, of course, you could have a combination of these issues.
 
#3 ·
Ill have to get a true AC manifold pressure gauge to check it properly. One issue i already found was the radiator fan seems to have little to no resistance when spun by hand, the condenser fan does work but it doesn't seem to cover very much of the condenser. I get the airflow and the reasons it could be doing what it is doing, it just seemed to have an airflow issue on the condenser side because of the normal operation at highway speeds versus relying on its own ability to draw air across the condenser at idle or stop and go traffic
 
#6 ·
One issue i already found was the radiator fan seems to have little to no resistance when spun by hand, the condenser fan does work but it doesn't seem to cover very much of the condenser. I get the airflow and the reasons it could be doing what it is doing, it just seemed to have an airflow issue on the condenser side because of the normal operation at highway speeds versus relying on its own ability to draw air across the condenser at idle or stop and go traffic
The engine cooling fan uses a viscous coupling clutch. Spin the fan as hard as you can on an engine that has not been started that day. If the fan rotates more than five times, you can bet the clutch is bad. You should feel some resistance and the fan may spin up to three times, depending on the ambient temperature.
 
#4 ·
You dont give year for your pathfinder.
Don't forget when at idle AC compressor is turning slowly so not pumping as much freon.
yes you need to check pressure, mainly low side but high can help diagnosis.
my 2003 had a variable displacement compressor, and although it still worked it didnt vary displacement correctly.
2003 also had an expansion valve, this was fine in this case. but compressor vendor required to be replaced to give warranty. The AC on these later vechicles is more complicated than older cars.

hope this helps. good luck
 
#5 ·
Reading your first post again my first guess is low freon, low low-side pressure at idle. lowest cost at fixing.
 
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