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Elated Technician
Elated Technician, ASE Advanced Master Technician
Category: Car
Satisfied Customers: 486
Experience:  16 yrs exp, Auto/Diesel Associates degree, ASE Master w/ Advanced cert, Saab Master and BMW level 4
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My car makes this loud screeching noise when I turn on the

Resolved Question:

My car makes this loud screeching noise when I turn on the air conditioner, and when I drive down the freeway it will makes that schreeching noise every so often, it only makes this screeching noise when I turn the air on, when the air os off it does not make that noise, I have already replaced the compressor and I have replaced the pulley that the compressor runs off of. I just don't know anymore. Please help!!!!! I swear the whole neiborhood can hear me when I turn the air on.
Submitted: 8 years ago.
Category: Car
Expert:  Elated Technician replied 8 years ago.



How did you tighten the belt? How much slack do you have?


Can you read the a/c system pressures when the car is running- high and low sides?




Customer: replied 8 years ago.
The belts are tight and no I dont know how to read the a/c system pressure when the car is running, I know that when I am driving the air is very cold and then it will get a litter warmer but then it goes back to being cold, it does that the whole time that I am driving.
Expert:  Elated Technician replied 8 years ago.



The reason I ask about the pressures is that they could be too high. This would cause the compressor to have too much load and make the belt slip on the pully. If you simply added a can of refrigerant, there is a good chance it is overcharged. Since you have a cold/warm duct, there is a chance the expansion valve is not operating properly or the condencer fan is not working well.


The next best step is to check the operating pressures to make sure you are not overcharged. The pressures should read 30/250 on a 70 degree day.




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