2004 Hyundai Sonata A/C

I have a 2004 Hyundai Sonata with a problem with the a/c. When at idle it will not blow cold. I notice the rpm change when turning the a/c on but it does not seem to engage the clutch on the compressor. However, while driving on the highway it will start blowing cold as it should. I was told by a friend it could be an issue with the drier or condenser and regarding a valve and could prevent the compressor clutch from engaging. I’m hoping I dont need to replace the compressor because the cost for a replacement alone is more than I’d like to spend. I can replace the part myself if need be, but I wanted some more insight to possible problems and solutions. If the clutch is not engaging but it still blows cold at highway speeds does it mean the compressor may not be the issue?

Raise the hood and see if the cooling fan is operating. Fans are not needed at high speeds but are necessary at low speeds.

An A/C shop could probably diagnose it and give a repair estimate for small or no cost.

Have a shop connect a set of refrigerant gauges to the AC system to check the state of charge of the system.

That’s the first thing done in your case.


I bought a recharge with gauge for low side. The charge showing on the gauge provided with the can says it’s normal. My friend was a mechanic for years before he lost his right eye. Now he makes parts for Harley-Davidson motor cycles. He said the valve he told me about being clogged or not operating properly could prevent the compressor clutch from engaging. If I fix that it may solve my problem. I’ll try what he suggested since he’s willing to look at it for me for free and if that doesn’t solve the issue then I guess I will have no choice but to have a shop diagnose the problem.