2002 LX470 AC issue please help (1 Viewer)

[brtn540]

Picked up N LX470 today for a good deal. AC wasn’t working so I took it to my friends shop to diagnose. He filled the refrigerant because it was no. Showed no signs of leaking after filling. Ac compressor would kick on for like 3 seconds then cut off. Relay is fine, he manually jumped the circuit in the relay box and it worked. Put the relay back and in and it AC still wont stay on. Any idea what it could be and how to fix?

 

[medtro]

What did your friend say?

 

[jLB]

This post, lists the things that would cause the vehicle to intentionally shut off the compressor:

New member .. need help

Thanks all for your responses. Julian Stead, the fan clutch is new less than week. I did that test for clutch but didn't see any difference while spinning the fan. Reall it's strange. I gave up with car.

forum.ih8mud.com

 

[brtn540]

What did your friend say?

He’s a master mechanic and owns his own shop. I had to leave before he could figure it out. Just wondered if anyone else had this problem.

 

[BullElk]

I had a very similar if not exact issue. @flintknapper solved my issue for me. Which was…. I suggest first checking the connector terminals on the compressor for corrosion. Then check resistance between the top two terminals, 1 and 2. If ohms aren’t between like 600 and 1050, then you need to replace compressor.

My A/C did same as yours and mine showed improper resistance. I replaced it and it works fine now.

 

[brtn540]

I had a very similar if not exact issue. @flintknapper solved my issue for me. Which was…. I suggest first checking the connector terminals on the compressor for corrosion. Then check resistance between the top two terminals, 1 and 2. If ohms aren’t between like 600 and 1050, then you need to replace compressor.

My A/C did same as yours and mine showed improper resistance. I replaced it and it works fine now.

Thank you so much for the info. We’ll try that.

 

[brtn540]

Looks like there's a pulse sensor on the back of the compressor that if it doesn't see the pulse it will tell the ECU to shut down the AC. Next step is checking out the wire to the sensor to see if there's a short. Will return back with our findings.

 

[brtn540]

Turns out a sensor is bad on the compressor and the entire compressor will need to be replaced.

 

[flintknapper]

Turns out a sensor is bad on the compressor and the entire compressor will need to be replaced.

The sensor is available by itself....but the cost (plus labor to install) puts it right in "New Compressor" territory.

The sensor is a speed sensor (lock out sensor). If it senses a compressor speed appreciably different than engine speed, it assumes the compressor is trying to seize up (or has). So in order to save the serpentine belt (which drives all your auxiliary items) it shuts down the compressor.

IF the sensor is determined to be bad....then yes, replacing the entire compressor is the way to go.

 

[brtn540]

Replaced the compressor today and the AC now works as it should.

 

[flintknapper]

Replaced the compressor today and the AC now works as it should.

Good work and thanks for the follow up. Most likely your 'lock out' sensor was bad. Replacing the compressor is the best course of action in that situation. Enjoy your cold air.