Tricky one here, just checking if it may be a common problem. If the car sits for a day, it will blow cold until I get it out on the highway. Upon initial start up, the compressor engages and all is right with the world. There is power to the compressor, tested with test light. The compressor just isn't engaging. I performed a leak check and nothing is leaking. Freon is full. Does anyone know of any faulty switches I should check and where they might be located? Thanks.

 

If there is power to the compressor and it is still not engaging, then there is something wrong with the compressor clutch.

The clutch gap may too large (worn down over time) and it will not engage. You would have to unbolt the pressure plate and remove a few of the shims. You may or may not be able to do this with the compressor bolted to the engine. It depends on how much room you have.

The other possibility is that the field coil is not working properly. You can do a resistance check on it. I don't know the proper resistance on an 03. A Haynes manual may have this information (~$20 at places like Autozone), but a shop manual will definitely have it.

 

do you know why it will engage after sitting overnight but quit after about 10 minutes? i measured the gap and it's in spec. I have heard of a lot of relays malfunctioning but there's still power to the compressor so i'm at a bit of a loss.

 

If there is power to the compressor, then the relay is working properly.

That pretty much narrows the problem to the coil or the clutch gap. The clutch gap would be much easier to fix.

The coil could get warm and start shorting internally and become weaker. It could be a bad/corroded ground.

The ground point is on the compressor and there is a Philips head screw on there. You may want to unscrew that connector and clean that contact with some sand paper to ensure that you have a good ground connection.

 

According to Helm, the compressor clutch coil resistance for 2003-2006 should be 3.9 to 4.3 ohms.

Energize it with a jumper to the battery, & the plate should move 0.35 to 0.6 mm (0.0138 to 0.0236 inch). They show that measurement being done with a dial indicator.