Dear Car Talk:
I have a 2013 Kia Soul. When I turn on the air conditioning, it doesn’t blow cold air at first. Once I get on the freeway and accelerate, it works for a few minutes. But soon after that, it goes back to only blowing room-temperature air — not cold air. It used to work fine. Do you know what could cause this and whether it’s going to be expensive to fix?
Thank you for your time. It’s nice to have someone knowledgeable and honest to ask!
— Rachel
Wait, Rachel. You have someone knowledgeable and honest to ask, and you still wrote to me?
Do I know what’s causing it and if it will be expensive to fix? Yes, and yes. The most likely cause of this problem is a bad air conditioning compressor.
If you remember your high school chemistry, you know that PV = nRT. Which, when translated from the scientific jargon, means you’re about to owe your mechanic at least $1,000.
Your air conditioning system uses a refrigerant, which starts out as a gas. The compressor “compresses” that gas into a liquid. And as that liquid gets converted back into a gas, its temperature drops. Ergo, air conditioning. The compressor is the most expensive part of your air conditioning system, unfortunately.
Now, you may get lucky, Rachel. Sometimes refrigerant can leak out from somewhere other than a bad compressor. That also would cause your AC to blow hot air. But your mechanic will check for a leak first by doing a vacuum test to see if your system holds a vacuum.
If you’re really lucky, you might just have a bad o-ring or hose, or a leak in your condenser or evaporator that let your coolant escape. All of those things are cheaper than a compressor. But at 11 years old, it’s likely that your compressor has failed. So, take it to your mechanic with a hopeful heart, but a full wallet, Rachel.
Got a question about cars? Write to Ray in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email by visiting the Car Talk website at www.cartalk.com.
