My Attempt and Progress at a DIY AC Compressor Replacement

[Supermoto]

Good day all. This thread is to document the process of finding and fixing the noise coming from my engine when running. I will update it until the problem is solved.

For the past month or two, I have noticed a distinct sound coming from the engine. It started as an occasional squeak that would speed up and slow down with RPMs, and evolved into a constant metallic squealing/grinding noise that gets so loud you can hear it over my full exhaust system. At first I thought it was the alternator bearing, as it sounded like it was coming from there. I took off the belt and gave it a spin, and while it did have an occasional small squeak, it wasnt until I turned the AC compressor that I believe i found the cause of the noise.

This video tries to catch how the compressor sounds when I spin it:

Im pretty sure this is supposed to be silent when I spin it, so now starts the journy of learning how to replace and AC compressor myself. I contacted my mechanic to ask for some advice, as the AC still blows cold and I dont want to have to replace the entire system if I can help it. He said if the AC still blows cold, the failure is most likely the bearing and this wouldnt contaminate the system. The next step is to order a new compressor and take off the current one to see if theres any metal shavings in the lines. If so, this job is about to get a lot more involved and expensive.

Currently I am looking to buy a new compressor, options on RockAuto range from a $200 UAC compressor, all the way up to buying a brand new Denso unit for $330. Obviously the Denso is the best choice for longetivity, so this is most likely the route I will be taking. Straight from Denso.com its $374 plus tax and all that, so I hope partgeeks is reliable.

In order for this job to go well, I need to remove the compressor and flush the system. I plan to use this flush bottle kit and a solvent such as laquer thinner or an AC flush to clear it all out. Because the system will be flushed I also will need to replace the dryer/accumulator. They are pretty cheap, so its alright.

The part that has me stumped is the expansion valve. It has been recommended that I change it, however I have no clue where the hell it is in this car. From the online parts diagrams it seems to be inside the dash near the firewall. If this is the case, Im just gonna leave it and pray it all works out. If anyone can shine some more light on this it would be much appreciated.

Thread will be updated over the coming weeks/months as I sort this issue out.

 

[beardedGTI]

This video tries to catch how the compressor sounds when I spin it:

You’re not spinning the compressor, you’re spinning the pulley. The clutch isn’t engaged so what you’re hearing is the pulley bearing going bad.

Your mechanic is right, there’s no metal shavings in your system and there’s no reason to disconnect the compressor. Pull the clutch off and either swap the pulley or track down the bearing in the pulley and punch it out and swap it. The latter is a ~$15 dollar job compared to whatever he charges to evacuate the system + ~400 for a compressor/dryer/condenser + another 100 to vacuum and refill the lines.

 

[Supermoto]

You’re not spinning the compressor, you’re spinning the pulley. The clutch isn’t engaged so what you’re hearing is the pulley bearing going bad.

Your mechanic is right, there’s no metal shavings in your system and there’s no reason to disconnect the compressor. Pull the clutch off and either swap the pulley or track down the bearing in the pulley and punch it out and swap it. The latter is a ~$15 dollar job compared to whatever he charges to evacuate the system + ~400 for a compressor/dryer/condenser + another 100 to vacuum and refill the lines.

From what I have read about this system there is no clutch and compressor is essentially "on" at all times. The system is engaged and disengaged from the swashplate inside the compressor. This is why I am looking to replace the entire compressor. I'll look into it more and see if this information is wrong, as I'd love to just replace a clutch bearing over the entire compressor.

 

[beardedGTI]

Not saying you are wrong. But if this is truly how it works, then I question if any of those compressors you listed will work. The first one you posted at the very top says "w/ Clutch". The second link doesn't have the original part number for the Denso listed so I can't look it up. But if you look at the GPD before it and the 4 Seasons after it they both have clutches. If the OEM doesn't have a clutch, how will you wire an aftermarket one to engage?

 

[Supermoto]

Not saying you are wrong. But if this is truly how it works, then I question if any of those compressors you listed will work. The first one you posted at the very top says "w/ Clutch". The second link doesn't have the original part number for the Denso listed so I can't look it up. But if you look at the GPD before it and the 4 Seasons after it they both have clutches. If the OEM doesn't have a clutch, how will you wire an aftermarket one to engage?

I just assumed the images weren't the actual units, and "with clutch" meant with the pulley assembly.

 

[2018gti]

From what I have read about this system there is no clutch and compressor is essentially "on" at all times

This could be just another forum rumor - on my 2018 at least, there is definitely a clutch. I can’t think of another way that the outer part of the pulley spins, while the center of it doesn’t move (when AC is off).

 

[Supermoto]

This could be just another forum rumor - on my 2018 at least, there is definitely a clutch. I can’t think of another way that the outer part of the pulley spins, while the center of it doesn’t move (when AC is off).

That's the point, it's said to be a direct drive system where the entire thing is spinning at all times. I'll take a closer look though. Also, no parts websites have a clutch assembly for our compressors.

 

[beardedGTI]

https://parts.vw.com/p/Volkswagen_2...-Compressor-ASSEMBLY/70108554/5Q0820803K.html

An A/C Compressor that may or may not include an A/C Compressor Clutch. From 03/01/2017. Includes: Compressor Clutch. R134A Refrigerant.

FFS does it or does it not have a clutch? I don't know what else to say other than it seems like even VW doesn't know. FWIW I've worked on other cars where there was no separate part # for the clutch or the bearing. It was basically up to the community to figure those out. That's not saying that an MK7 has one, just that I wouldn't be surprised if there is one and it's not listed on any parts websites. Best of luck to you and keep us posted on what you find.

 

[Supermoto]

https://parts.vw.com/p/Volkswagen_2...-Compressor-ASSEMBLY/70108554/5Q0820803K.html

FFS does it or does it not have a clutch? I don't know what else to say other than it seems like even VW doesn't know. FWIW I've worked on other cars where there was no separate part # for the clutch or the bearing. It was basically up to the community to figure those out. That's not saying that an MK7 has one, just that I wouldn't be surprised if there is one and it's not listed on any parts websites. Best of luck to you and keep us posted on what you find.

The plot thickens once again I'll give vw a call and see what they say. I'll probably just pop the pulley off and see what happens.

 

[IWMTom]

Here's the two different part diagrams of without clutch and with clutch. There's an extra electrical connector if you have the compressor with clutch.

 

[beardedGTI]

So I had to take my wifes 2020 SE in for a software update this morning and chatted with their master tech. Sure enough VW uses both. He wasn't able to offer any explanation on why or what models had which. We popped the hood after mine was done and he looked at it and immediately confirmed it had a clutch.

 

[Supermoto]

Here's the two different part diagrams of without clutch and with clutch. There's an extra electrical connector if you have the compressor with clutch.

View attachment 220837

View attachment 220838

Very useful post, thank you for that. Based on the pulley alone it appears mine has a clutch (mine has that triangle shaped bit on the pulley) and it's thicker than the top pic. So I will pull it off today and check out the bearing. Thank you again. You might have saved me a load of money.

I suppose the next question is where do I get a clutch from if no one actually specifies the part number?

 

[beardedGTI]

I suppose the next question is where do I get a clutch from if no one actually specifies the part number?

Pull it off and verify that it is indeed the pulley bearing. If so, check for part number stamped on it.

 

[Supermoto]

Pull it off and verify that it is indeed the pulley bearing. If so, check for part number stamped on it.

Called VW with the VIN, they said its an entire compressor that needs to be replaced. I will pull the clutch off today and verify its the bearing. The thing is when I turn it by hand, it feels like im turning the entire compressor based on how much inertia it has behind it when I turn it. It doesn't feel like a freewheeling clutch pully. Regardless, next step is to pull it all apart. I will continue to update.

Edit: The other thing is the sound comes regardless if the AC is on or off. Am I right in assuming that when the AC is on and the clutch is engaged, the clutch bearing is no longer spinning as the entire unit is moving together?

 

[Strange Mud]

although VW would replace the entire compressor a good DIY Mechanic may be able to rebuild/replace bearing if that's the problem. Do you have a way to recover/purge/replace the refrigerant?