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Q: I have a 2004 Kia SuV. Air conditioning works ok except when I go up a hill. Then it cuts out and may or may not come back on. I the

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I have a 2004 Kia SuV. Air conditioner works ok except when I go up a hill. Then it cuts out and may or may not come back on. I the car levels to a flat area, the air will still not work. any suggestions?

My car has 147000 miles.
My car has an automatic transmission.

A: I suspect you have a cooling system issue o...

I suspect you have a cooling system issue or low refrigerant. When you are climbing a hill, your car is experiencing increased load that produces as much a ten times more heat than if it were cruising on a flat. Your condenser is mounted at the front of your radiator and adds heat to the radiator. When you are climbing a hill, if your cooling system has any problems, it will not be able to dissipate the extra heat. Two things can occur as a result of this. The car can choose to turn your A/C system off or the condenser will not be able to keep the high side of the A/C system cool enough. When the high side of the A/C system gets to hot, the pressure rises and the pressure switch will turn the compressor off. Both of these issue has to do with insufficient cooling.

In the case of low refrigerant, as the system continues to run for an extended period of time, the low side pressure will become to low and the compressor will cycle quickly. At this point you will get intermittent moments of cool air. But never as cool as it should be. What's happening is once a low system pumps most of the refrigerant to the high side, it leaves the low side at a deficit. It will stay this way until the you turn the A/C off for a time and allow the pressures to equalize.

Either way, you should have both your A/C system serviced and your cooling system inspected by a certified technician, like one from YourMechanic. One of our mobile experts will be able to come to your home to do so.

Good luck!

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