A/C work - should i? must i?

[benIV]

I’ve narrowed down my a/c problem to a few things:

little fan is bad. compressor is bad.

i’m replacing these and the drier. Do i really need to drain the coolant (to remove a line or two) or can these components be replaced while leaving the coolant system alone?

 

[cwatson9510]

Is your whole compressor shot or just the clutch and coil? I'm going to be replacing mine this week. Just the clutch and coil is much cheaper, and you don't have to replace the drier or drain any coolant. You can do it without evacuating the system too. It's not often the compressor itself goes bad on our cars.

 

[VChristian]

I have run quite a few Mk4 TDI diesels over the years, and AC compressors are a constant problem. Like cwatson9510 says the problem is often that the clutch fails. Right now, I average between two and three clutch coils per compressor. So I just buy a bunch of coils, and swap them on when they fail. The failures are always exhibited as an open coil, which is quickly diagnosed.

It is pretty easy on the ALH to drop the compressor, connected to the cooling system, and with a bucket or something to rest the compressor on, to pull the clutch and pulley and swap out the coil. As I recall the routine is down to about an hour, not busting while doing it. Its hard to bust while doing it, because these coils seem to like to fail when it is 90F outside.

At one point I started getting compressors with "lifetime" warranties, but frankly it is cheaper and faster to just change an $19 coil, rather than do a bunch of work changing the compressor, and evac and recharging the coolant.

 

[KrashDH]

The RCV inside of the compressor is a known failure point. My clutch and coil was fine. I rebuilt the compressor as the internals were in great shape. Also replaced the drier, thermal expansion valve while I was doing things. I don't recall having to drain any coolant...

 

[VChristian]

The RCV inside of the compressor is a known failure point. My clutch and coil was fine. I rebuilt the compressor as the internals were in great shape. Also replaced the drier, thermal expansion valve while I was doing things. I don't recall having to drain any coolant...

I would be interested in how you replaced the dryer and the expansion valve without opening the refrigerant loop, and then subsequently evac and recharge.

 

[SoTxBill]

I would be interested in how you replaced the dryer and the expansion valve without opening the refrigerant loop, and then subsequently evac and recharge.

Freon and coolant?? one is Freon, the other is antifreeze. I think he said that he did not need to drain the antifreeze to change out the compressor. Not to be confused with r134 (coolant) freon.

 

[KrashDH]

Freon and coolant?? one is Freon, the other is antifreeze. I think he said that he did not need to drain the antifreeze to change out the compressor. Not to be confused with r134 (coolant) freon.

That is correct... I most definitely broke the refrigerant loop to do the a/c work...not to be confused with the antifreeze/coolant...

 

[AndyBees]

As others have stated...

Refrigerant is what's inside the AC system (in this case, R-134a)

Antifreeze/water (coolant) is what's inside the cooling system of the engine.

R-134a is not Freon........ Freon is a brand name for the Refrigerants R-12, R-13B1, R-22, R-502, and R-503 manufactured by The Chemours Company.

 

[BobnOH]

Thanks for that Andy. Might add the only correct method servicing these things if you open up the refrigerant lines is to purge it and refill by weight with x ounces of oil. Not to say many don't do this and still have working systems. It will cost an extra hundred or two, but a good workflow would be to take it to AC tech, have them purge it, do your repairs, then drive it back in to be filled.

 

[KrashDH]

Thanks for that Andy. Might add the only correct method servicing these things if you open up the refrigerant lines is to purge it and refill by weight with x ounces of oil. Not to say many don't do this and still have working systems. It will cost an extra hundred or two, but a good workflow would be to take it to AC tech, have them purge it, do your repairs, then drive it back in to be filled.

I used to be scared of A/C systems, it was really the only thing that I couldn't do (and I've torn down and rebuilt a few engines in my day).

After learning and diving into them, it's really a pretty simple process. I've done both the TDI and my Cummins systems, as well as my old Tacoma's as well.

I should clarify though, on the Golf I did take it to a reputable shop that does A/C work to recover the refrigerant that was in the car before I started on the work. Don't want that stuff going into the atmosphere or your lungs, it's NASTY.

I rebuilt and replaced as necessary, adding r134a by weight, ensuring that the pressures were in range for the ambient outside temperature for confirmation.

As far as the oil is concerned, the manual should state how many oz. should be added to each component replaced. So if you're not replacing any components, you should not add oil. Drawing a vac on the system should not pull oil from the system. I had removed the compressor, drained the oil from it and re-built it, as well as replaced the drier. I added only the amount of oil necessary for those 2 components in the system.

 

[BobnOH]

........................After learning and diving into them, it's really a pretty simple process. I've done both the TDI and my Cummins systems, as well as my old Tacoma's as well.................

Absolutely worth the plunge, some knowledge, couple tools, you will save a lot of time and effort. And all AC systems are basically the same, so your friends and family make out too.

But if you just pull it together from forum threads and other anecdotal evidence you may be disappointed in the results.

 

[KrashDH]

Absolutely worth the plunge, some knowledge, couple tools, you will save a lot of time and effort. And all AC systems are basically the same, so your friends and family make out too.

But if you just pull it together from forum threads and other anecdotal evidence you may be disappointed in the results.

Very true. In my conquest you learn to take a lot of posts with a grain of salt, and can usually determine the valuable ones that will get you to your goal. So far so good on the A/C front for me!