Automotive Air Conditioning Information Forum

Just replaced my old compressor with a new one.
Let me give you a back story why. I overfilled my old one and that broke it. Brought it to the dealer for an evac and recharge. That didnt work. They told me the clutch was bad. So instead of just buying a clutch, i just replaced it with a brand new one.

Now. After installing the new one, the ac clutch is always engaged. After 5 secs of starting the car, without the ac on, you will hear that click. Even without pressing the ac button the ac is still cold. I changed the relays, fuses. I dont really know what to do anymore as i am lost on why this is happening.

Pull the clutch relay, if it doesn't engage then, you'll know that something is telling the relay to energize.

wptski wrote:Pull the clutch relay, if it doesn't engage then, you'll know that something is telling the relay to energize.

I did. When the relay is out it doesnt engage. When its on it engages. What could it be?

You'll have to get a schematic and trace where the signal goes. In the older models anyway the control panel pulls a wire low to demand A/C. This ground signal passes through the pressure switch to the ECU / PCM. If the control panel is bad or the wire is shorted to ground, it will come on as soon as the engine reaches a stable rpm and stay on. Your compressor may have a thermal switch in the loop, if it has two small wires and one big wire. Check that the switch part isn't faulted to ground.

It may be all CAN bus now though.

mk378 wrote:You'll have to get a schematic and trace where the signal goes. In the older models anyway the control panel pulls a wire low to demand A/C. This ground signal passes through the pressure switch to the ECU / PCM. If the control panel is bad or the wire is shorted to ground, it will come on as soon as the engine reaches a stable rpm and stay on. Your compressor may have a thermal switch in the loop, if it has two small wires and one big wire. Check that the switch part isn't faulted to ground.

It may be all CAN bus now though.

So if it is not those wires? Its the pcu unit itself?