AC compressor replacement DIY?

[Addamsonflint]

Hey everyone,

I have searched all over and can't find a basic DIY thread for ac compressor replacement. There's tons of thread of "what's wrong with my AC???", trouble-shooting, etc. But I can't seem to find a DIY for replacement.

Any help would be appreciated.

Thanks,

 

[firehawk618]

It's pretty simple.

Jack the car up, remove the cover under the engine, remove the serpentine belt, unhook one electrical connector on the a/c compressor, remove the 2 bolts holding the compressor to the engine, remove the hoses.

This is assuming your system has already been discharged. If not discharge the system first.

 

[freakwithracket]

I'll add to firehawk's statement. The compressor will be in there tight. You won't be able to remove it with your bare hands. You will need a crowbar. Simply wedge it out of there.

 

[Addamsonflint]

That is good news to hear- thank you gentlemen. I had read something somewhere that, you not only had to take off your serpentine belt, but remove a lot more crap before you could take it out. And there sure isn't much room for doing work at the bottom of our engines.


On a side note- how hard do you guys feel a clutch install is?

I've looked over the DIY for that- I'm a "decent" mechanic, but it still looks pretty damn daunting, many many hours in fact, especially if you haven't done one before.

 

[PDJetta]

For the compressor, use new O-rings on the connections (get them from the dealer, the ones designed for the A/C) and coat them with compressor oil. You will have to figure out how much (if any, the compressor may come with oil in it) oil you need to add to the compressor. The '05.5 I just reinstalled a compressor on takes PAG 46 oil. I would imagine yours is the same, but verify. Evacuate the system with an A/C vacuum pump and see if it holds vacuum for 15 minutes or so. If it does, charge the required amount of refrigerant gas through the low servcice port. I used a food scale to weigh the last can of refrigerant tapped. It worked fine.

As for the clutch, figure if you've never replaced one, two solid days. I did it solo using a floor jack and $75 harbor freight transmission jack and a home made engine support brace. Drain the dransaxle of gear oil and remove the passenger side inner CV joint drive flange from the transaxle for clearance.

--Nate

 

[KLXD]

Loosen the two mount bolts about a turn and whack them with a hammer and punch. This will drive the sliding bushings back so you don't need a pry bar to get it out. (Hopefully)

 

[firehawk618]

Loosen the two mount bolts about a turn and whack them with a hammer and punch. This will drive the sliding bushings back so you don't need a pry bar to get it out. (Hopefully)

Yes, or after you use a pry bar to walk it out, put the bolts in a ways and smack the bolt with a hammer. Makes re-installation so much easier.

 

[john_tsouris@hotmail.com]

For the compressor, charge the REQUIRED AMOUNT of refrigerant gas through the low servcice port. I used a food scale to weigh the last can of refrigerant tapped. It worked fine.


--Nate

Where does one find information on the required amount of oil and required amount of refrigerant?

Also, is there a way using VCDS to monitor how much refrigerant to install?

Does the system need to be evacuated only to leak check it, or to remove moist air prior to refrigerant installation?

I'm on my third compressor and I don't really want to pop $1200 for a part that costs $300, especially when the VW ECU doesn't monitor for high pressure to shut down and prevent damage to the compressor.... causing us to buy multiple compressors......

Thanks.

 

[PDJetta]

John:

If you are on your third compressor, you may have trash or debris from a previous compressor failure in the A/C refrigerant circuit. What were the other two compressors replaced?

To be absolutely the system is clean, it should be discharged, flushed, the receiver drier and expansion valve replaced, the correct amount of PAG 46 oil installed, a vacuum drawn on the system, and the refrigerant weighed in.

What vehicle do you ned to know the refrigerant and compressor oil capacities for? They are quire different for the A4 and A5.

From my Bentley manual:
For the A4, 26 +- 1.8 ounces of refrigerant are used and 135 +- 15 cc of oil are used.

For the A5, 18.8 +- .9 ounces of refrigerant are used and 110 +- 10 cc of compressor oil is used.

The VCDS does not monitor the compressor, as far as I know.

--Nate

 

[john_tsouris@hotmail.com]

Thanks for the info.

I don't understand "What were the compressors replaced?" Did you mean why? Did you mean when? What they were were two factory compressors....

Someone flushed the system last time.

Looking at the trouble and expense on this repair, I think I'm ready to leave VW and just trade this in. I've spent about $10,000 on repairs on this TDI since I bought it new in 2006. And now it's another $1,000.

This last compressor failure was because I hit a pothole which wiggled a connector and gave me a throttle position sensor error, which put the car in limp mode. Know what limp mode does? It shuts the damn cooling fans off, but lets the AC compressor pump away..... destroying it the second you sit at a red light. I mean, c'mon VW.

The first compressor went for almost the same reason. A fan got sand in the brushes and shut down. VW does not have a safety switch in the AC system for overpressure, so that took out the compressor.

Thanks again.

 

[workinman]

compressor

Hey everyone,

I have searched all over and can't find a basic DIY thread for ac compressor replacement. There's tons of thread of "what's wrong with my AC???", trouble-shooting, etc. But I can't seem to find a DIY for replacement.

Any help would be appreciated.

Thanks,

I ordered a new compressor and drier reciever for my car last week . Was not real hard to replace the compressor. The drier was a little hard to remove. I got a kit that had the orings included. The compressor had the clutch installed . I had the parts the next day after ordering . works good now . Jim

 

[MoBeau]

My TDi Mk7 AC is starting to fail at 120k miles. I noticed the the fan runs every time engin is shut down. Engine temp gauge seems normal 200f. What could be the cause?

 

[wonneber]

They do run for a few minutes if it hot.
The dash gauge does not have to show over heating.
My 2014 Jetta Sport wagon and 2021 Atlas do this also.

 

[Nuje]

Engine temp gauge seems normal 200f. What could be the cause?

Engine temp gauge is nearly useless - it reads straight up (90C / 190F) from around 75-105C. I've done a 30km long climb through the mountains and had the oil and coolant temp well over 100C (closer to 110°C = ~225°F) and the dash gauge never budges past that straight up 90°C mark.

 

[Rob Mayercik]

This last compressor failure was because I hit a pothole which wiggled a connector and gave me a throttle position sensor error, which put the car in limp mode. Know what limp mode does? It shuts the damn cooling fans off, but lets the AC compressor pump away..... destroying it the second you sit at a red light. I mean, c'mon VW.

The bit about limp mode disabling the cooling fans caught my eye - don't think I've heard this before. Guess they were trying to reduce load on the engine by reducing electrical consumption (and hence alternator drag), but that does seem to invite risk of overheating (and, of course, the collateral damage to the A/C system as mentioned).

I wonder if that particular "feature" (locking out the cooling fans in limp mode) is something that a tuner could address?

 

[BobnOH]

The bit about limp mode disabling the cooling fans caught my eye - don't think I've heard this before.................snip.................

Perhaps that's true, IDK, but it doesn't make sense.

 

[KLXD]

Not clear to me why it would hurt the pump anyway. The system pressure would go up and the cooling would get worse but is there not a high pressure cutoff switch?

Even if there's not, the pump is just going to see a higher inlet pressure and discharge pressure.

At some point the R/V on the pump might let go but it's replaceable, no?

Also I find it unlikely VW would put in a failure mode that could damage the motor. Limp is supposed to protect it.

 

[Genesis]

No, what happens is the RCV bypasses internally, but the problem is that the only thing that COOLS the compressor is the circulating gas. So if most of it is being bypassed it will cook the oil in it and destroy it.

That is why non-working fans destroy the compressor even though the engine does not overheat.

 

[John Wesley Hardin]

compressor


I ordered a new compressor and drier reciever for my car last week . Was not real hard to replace the compressor. The drier was a little hard to remove. I got a kit that had the orings included. The compressor had the clutch installed . I had the parts the next day after ordering . works good now . Jim

You mind if I ask where you bought the compressor kit ? Im about to do the same thing.

 

[John Wesley Hardin]

No, what happens is the RCV bypasses internally, but the problem is that the only thing that COOLS the compressor is the circulating gas. So if most of it is being bypassed it will cook the oil in it and destroy it.

That is why non-working fans destroy the compressor even though the engine does not overheat.

True that. Thats why I believe my compressor bit the dust

 

[KLXD]

No, what happens is the RCV bypasses internally, but the problem is that the only thing that COOLS the compressor is the circulating gas. So if most of it is being bypassed it will cook the oil in it and destroy it.

That is why non-working fans destroy the compressor even though the engine does not overheat.

Fair enough but the high pressure switch should shut it off long before this happens. While I haven't checked the wiring diagram to verify it has one I've seen enough references to one to think it's there.

Is there a limp mode that shuts the fans off when the TPS quits? I guess the bump that killed the TPS couldn't have also killed the fans. (sarcasm)

 

[benIV]

when you vac the lines after assembly, does that pull the oil out too, so you have an empty system and just need to refill with oil and refrigerant per spec?

 

[Genesis]

No; the oil is not volatile.

MOST of the oil is normally in the compressor, but not all. A new compressor usually comes pre-charged with oil, so you will actually be over-oiled by an ounce or so if you do not completely flush the system (or replace all the components.) Check with whoever is supplying your compressor assuming you are replacing it to see if it has oil in it already and, if so, how much.

 

[KLXD]

Yep. The book has the expected oil in each component so if you replace the pump without flushing you're supposed to drain it and add back only the requisite amount for any replaced part.