Hi all - with summer heating up, I would like to fix my AC soon. Beyond recharging, I’ve done no AC work in the past and need guidance. I tried charging the system yesterday, but low never got above 12psi while the gap tool read between 500 and 525 psi depending on fan strength (it was about 68* outside).

The air is no cooler today.

I posted before I purchased the LR3 and was advised to look at a hex bolt and determine if it’s spinning. Beginner question here, but where am I looking? From top/bottom/through grille etc.

If the compressor is indeed toast, this forum suggests that it’s not hard, but rather annoying to replace. I think this can be said about basically everything on these vehicles. I would prefer to not mess with pulleys etc but if this can be done with minimal permanent damage, I’m willing to try. I may also ask a local Indy, if willing, what their labor would be if I supplied a compressor.

But I’m getting ahead of myself and need to diagnose the problem first. Any help would be appreciated.

 

It’s the rusty hex bolt in the center of the compressor pulley. You need a good flashlight. I tried to give perspective in this picture so you can see exactly where to look.

 

If the clutch on the compressor pulley is engaging you should see everything spinning. If you were low on gas it would not engage. It would also not engage if pressure were too high but that is unlikely unless there was a blockage somewhere. I think compressors are about the last thing to fail in an AC system. More likely incorrect charge or failure of a sensor. I did have a compressor fail on my L322 but in that case it was the drive pulley that failed. There are bolts that are designed to shear off in the event the compressor seizes up. Mine broke for no apparent reason. Nothing wrong with the compressor.

 

These compressors are variable displacement with no clutch. That’s why the center hex is always spinning with the motor and a quick indicator of compressor failure.

Here’s a good article on how they work.

https://axleaddict.com/auto-repair/V...nt-Compressors

 

I stand corrected. Will have to study up.

 

I had never heard of a variable displacement a/c compressor until I had to fix my 07 just over a year ago. It was a huge learning curve for me. I kept waiting for the clutch to engage while charging and nothing was happening. After much reading, I learned about the shear plate pulley system and realized my compressor was shot. After replacing the compressor and charging again, I still couldn't get the system to pump. Hours of troubleshooting, more reading, tracing wires, more reading, I finally narrowed it down to the climate control panel. This panel sends the PWM (on-off %) signal to the refrigerant solenoid on the compressor. Depending on demand, the solenoid adjusts the swashplate to increase or decrease the compression. This circuit was not working on mine.

It's really pretty cool how it works, but I had no clue what I was doing or getting into when I started.