Hey everyone! I'm brand new to the forum. I'm a long time wrencher on various vehicles and have always enjoyed enthusiast forums when trying to solve probs. I was hoping there might be some smart folks here who can help direct me to some resources as I undertake...

A $14k repair on my wife's 2007 LR3 HSE V8 - US spec. Well, the stealership quoted that out to replace the AC compressor, desiccant bag, evaporator, evap expansion valve. LR tech said compressor was failing (inconsistent pressure), and there were restrictions in the evaporator and evap expansion valve. Line item on replacing each one was between $2-3k each. Obviously, quite a ridiculous quote and wasn't something I was going to have them do.

I'd theorize the AC compressor beat itself to **** with all the upstream restrictions (and from the tech's notes). So, it probably makes sense to replace components. I haven't worked much on car HVAC systems, but I know how how residential HVAC systems work. Concepts and processes are similar. Also, I've wrenched around on the LR3 for a bit on less invasive repairs. Swapping out sensors, replacing alternators, door lock actuators, blower fans and all that jazz.

Questions to the braintrust here:

- Are there any forum threads I can reference as I start my repair? I did a quick thread search above and I wasn't able to come up with any relevant hits (maybe there were some buried deep in search results)
- Any major issues or challenges I should familiarize myself with before I start in on this repair? Hopefully this isn't an engine out repair because there's some dumb fastener I need to get to and I'll have to spend 20-hours of wrenching just to get to it.
- Anyone have any links to factory service manuals, YouTube vids, or other resources I might be able to review so I can familiarize myself with the repair?
- How many cases of beer should I purchase to help me along my journey?

Thanks again for all of your thoughts, help, advice and patience.

 

I bought my 2007 LR3 HSE in February with bad a/c among a few other major problems.

I replaced the a/c compressor, condenser coil in front of the radiator and the dryer/filter/desiccant canister which is attached to the condenser.

I first noticed a refrigerant leak dye stain at the rear a/c unit connection that runs along the frame near where the suspension compressor is mounted. I replaced these o-rings, pulled a vacuum and it held just fine.




I charged the system, tried to get cold air and nothing. Kept watching the compressor clutch mounting bolt waiting for it to cycle on/off, but it never would. Then I tried to manually turn it with a wrench and realized the compressor was seized. Then I read that these are variable displacement compressors that spin all the time and adjust by controlling the on/off signal to a refrigerant solenoid. When they fail, the front plate shears off and allows the belts to continue to run the rest of the vehicle instead of leaving you stranded. This is the area you would normally find a magnetic clutch. You can see where it is sheared off below.



They say you should replace the condenser, dryer, and expansion valve when replacing a compressor due to the all the crap that flows out of the failed compressor. I don’t know about the evaporator coil. That would require dash removal.

They also say these variable displacement compressors cannot run without refrigerant or they will chew themselves up due to poor lubrication. I think that’s what happened to mine.

So, check for leaks fist. Look in that same spot by the suspension compressor and any other connections for dye stains.

The compressor is no fun to remove, but it is doable. You’re going to need various combinations of wrenches, sockets, extensions, wobbles, and a TON of patience. Take the power steering pump off at the bracket mount. There’s a recent thread on here about that. You don’t need to remove the hydraulic lines, you can lay it out of the way.

You’ll probably need to pull the radiator and condenser coil out as an assembly. It’s not fun. I think it might be easier to remove the body first. That’s a joke, sort of. I trimmed the mounting ear on the passenger side of the radiator to make it go back in easier.

After I got everything back together, I still could not get the compressor to pump refrigerant. I could manually apply battery voltage directly to the compressor and make it work, so I knew that mechanically everything was working.

After some deep electrical troubleshooting, I found that the temp control module had failed
internally at the circuit that controls the on/off signal to the compressor’s refrigerant pressure solenoid. I bought a used one on eBay. Now I have really nice cold air!

Look in the sticky’s tech post. There’s a link to a factory service manual. I also use Mitchel 1 DIY for my family fleet.

Good luck!

 

Really appreciate your write-up!

My wife took the LR3 into Land Rover for an evaluation, so I have a full write-up from techs what they believe is wrong. Here's what they state:
So, pretty much they've determined that the AC compressor is shot, there's restrictions in the evaporator and the expansion valve and components need to be replaced. Tech sounds like they isolated each component as part of diagnostic testing, so I'm pretty confident my task list is fairly accurate. Obviously, I'm going to replace the broken coin tray when I pull the dash

Again, thanks for your write-up. I've had to tinker around tight engine bays before and have a pretty healthy assortment of tools to get to tight places. Even though there's always a bolt or two which take a few hours figuring out how to get out (and get back in). I'll do some more reading up in the tech threads and review the FSM posted! Appreciate all the help and advice! Thanks again!

 

I would highly recommend starting with P-Bod’s suggestion of applying 12V directly to the AC compressor. That will at least verify if the compressor is the issue.

 

After you remove the expansion valve, you might consider trying to back flush the evaporator coil to remove any debris. If it flows free, you'll save yourself a lot of work on dash removal.

 

Really good idea! Thank you. I'm about to put in an order for parts and will start wrenching in a few weeks. Trying to game plan it out and figure out shortcuts ahead of time. This is going on the list, ha.

 

From the LR tech, sounded like there was inconsistent pressure readings from the compressor directly indicating it was going bad. High side restrictions could have caused it. What happens is the compressor tries to compress a liquid refrigerant which can't be compressed and compressor internals can get damaged. I'm pulling this from my experience with household HVAC systems, but the same concepts apply to automotive HVAC. Bypassing the refrigerant solenoid to test the compressor is a mute point since there's already evidence the compressor isn't able to produce consistent pressure.

Or was there something else I was missing?

 

@gorgalor, I will defer to your experience working with residential HVAC systems, but I will share my observations. There are a significant number of threads with people discussing AC issues on the LR3. A number of them end up replacing the compressor, which is a tremendous amount of labor, and among that group a small number seem to indicate that the issue was not resolved by replacing the compressor.

In my situation, AC output for many years was just noticeable on warm days and pretty much nonexistent on hot days. My Faultmate tool can read live values, and it was showing fluctuating current at the compressor, going from 0.75A down to 0 and then cycling back. Using an external power supply, I applied 12V DC directly to the compressor. Current reading then showed a steady 0.75A and the AC output was nice and cold. I wired up a 12V feed from an unused fuse location so that the compressor would turn on when the car was running. I let the car run like this for a week of occasional driving, but after giving it some thought, I didn't feel comfortable having the compressor powered in this manner. Our clutchless compressor normally receives a pulse width modulated 12V feed and the way I had wired things up was signalling the compressor to run at full output 100% of the time. On at least two occasions during testing, I heard the bypass valve open and could smell refrigerant.

I decided to disassemble the 12V feed I had made and reattach the original power connector. Surprisingly, the AC has been working fine ever since! Current values are steady and AC output has been strong and instantaneous. I'm not sure what changed. Perhaps forcing the compressor to run at full output unclogged something in the refrigerant pipes. Maybe the connector at the compressor was dirty. There is also the possibility that I've now damaged something on my AC system, though I don't see any evidence of that so far. One thing I have not done is compare the pressure readings from before and after.

My situation is a sample size of one and will not work in all cases. I'm just happy that my AC is working right before another hot summer starts. Wishing you the best on your repairs.