Will the air condiditing only run effectively when the car's going over 40mph?


Asked by Aug 24, 2013 at 04:03 PM about the 2000 Pontiac Sunfire

Question type: Maintenance & Repair

My brother bought a 2000 Pontiac Sunfire a few months ago. They were apparently assured by the mechanic when the took it in that they could get air conditioning working for $450. The air would seem to work for a little while then after a day or so it would only blow cold/cool air if the car is going over 40mph. $1300 and several return visits later supposedly the whole air conditioning system has been replace the mechanic is telling him that's just how the air for that particular model works. Is that accurate or BS and what are his best options at this point?

Thank you

6 Answers


Check to see if electric fan at radiator is coming on when ac is turned on.


He says it looks like the fan is coming on.

1 out of 1 people think this is helpful.

It should be very obvious that it is on. If its not coming on or not blowing real hard I would check into why not. This could cause ac not to cool properly at idle or low speeds.


Does your ac blow good and strong out the front vents when driving but blows weak or changes to defrost vents when you slow down?

1 out of 1 people think this is helpful.

It blows really strong out the front when its set to recirculating and driving. It weakens and gets warmer at slower speeds or in park but the doesn't change vents. Thank you for trying to help us figure this out.

2 out of 2 people think this is helpful.

Ok with what you have described it sure sounds like the radiator fan is not operating properly. If its not blowing properly the freon will not cool properly and will cause the compressor to turn off at lower speeds or at an idle. Look at the front of the compressor where the belt goes on it. Make sure that the clutch on compressor is ingaged and spinning. If not its either a radiator fan issue or a low freon issue. If it is spinning feel the ac lines. Are they cold? If so then check the dampers in the duct work of the vents. If yours is controlled by vacuum they could be closing when you slow down due to a vacuum leak somewhere.

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