Hi all, I’m in the UK and have a 2001 RX300 with an odd problem - the air conditioning will not switch off. By that I mean that the compressor keeps turning and the lines are always cold in the engine bay along with a ton of water dripping from the evaporator. This is even if I switch the entire unit off inside the car. The green illuminated AC button does nothing if it is pressed and the compressor just spins permanently. Is there a relay/fuse on these that controls the compressor? Thanks everyone in advance.

 

Does the switch feel funny and or does the green light stay lit?
You may also like to see how the compressor responds when you move the temperature to Hot.

Try to locate an electrical diagram as that will help you trace from switch to compressor. There is an ECU that controls the electrical clutch on the compressor. Maybe the clutch is stuck mechanically or the clutch relay is fused together.

You can try reading the voltage on the wires leading to the clutch as you change the switch position.

Note: For copyright reasons we can not keep the diagram on site. If you dig through the net, you will find it some where. Good luck

Salim

 

Great! Thanks Salim, much appreciated. I’m actually leaning toward the clutch being stuck mechanically - I might get the big hammer to it (only joking). Also the condenser fan constantly cycles on and off every 10 or so seconds. The control unit in the dash seems to work fine ie all the buttons and functions work it’s just the actual AC is on permanently!

 

Is your vents direction dial on windows in any manner? As safety measure, AC will NOT turn off, if it is. Defogging. Even if the light comes off, it will still run.
Is clutch cycling or it runs permanently? Then you either have short somewhere locking power supply to the clutch or it froze.
There should be clutch connector at the top of it. You can unplug it. If it still spins, then it's mechanical, if it stopped - electrical.
Fast fix is to replace serpentine belt with non AC model one or simply take AC belt off. I do not remember if you have dedicated belt for AC or not, been a while since we sold our 99 RX.

 

AC is on the same belt as the alternator. Power steering is on its own belt.

 

Unplug it then. Or, pull AC fuse out. Same difference. Still spins non stop=seized clutch.