AC compressor bypass

[leightonw]

An A/C line was cut from the compressor by the previous owner and don't want to spend over $300 on a new line. I've decided to remove compressor and bypass it, so before I start doing the what belt size fits ordeal, anyone know the belt size to bypass it? OE belt is K060625.

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[EuroxS4]

I dont see why you would remove it to by pass it with the a/c off the compressor pulley is in free wheel.Not causing any drag on the motor until the clutch is turned on.

[leightonw]

A compressor will eventually seize up without the freon in it and snap the belt. Had it happen to my chevy silverado.

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[jacobsen]

It's not a big expensive deal to fix that. If the car is in major disrepair and it's not worth it I can see skipping it. As has been mentioned it's free wheel. Which continuously lubricates the working parts of the compressor. I noticed that the B7 accessory belt is very tight, I would imagine you could use it.

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[EuroxS4]

A compressor will eventually seize up without the freon in it and snap the belt. Had it happen to my chevy silverado.

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Silverado and A4 are worlds apart.If your worried put a little of pag oil in.Seal the line.And leave the compressor in.In Freewheel it wount do anything either way.Waster of time removing it if you ask me.As for the belt here you go:


Gates K060450
Dayco 5060450
Napa 25-060450
Napa 25060450
Goodyear 4060450
Bando 6PK1143

IIRC you need to remove the idler thats it.

[Kevin C]

Since the AC pump is clutch-less, the guts are always spinning. When the system doesn't have refrigerant, the lubricant in the system can't circulate. That will seize the compressor. If the fuse links on the front pulley doesn't let go first, the compressor will grenade. This isn't theoretical, its happen to people that ran their cars after doing major work that damaged a compressor line and didn't get the system recharged.

The AC uses a variable displacement pump with no clutch. When set to off, the system is still pumping but at a very low capacity.

[texasboy21]

No need to remove the idler, just run the shorter belt.

[leightonw]

I'll try the belt with idler puller attached, I have no use for A/C being in Alaska. This is my first German car so its fairly new to me even being very mechanically inclined.

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[diagnosticator]

I'll try the belt with idler puller attached, I have no use for A/C being in Alaska. This is my first German car so its fairly new to me even being very mechanically inclined.

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Actually, the AC is very useful in winter and summer, the dehumidified air helps defogging and defrosting and helps keep the windows clear. Without the AC, the windows can fog up with no way to clear them.

[jacobsen]

Actually, the AC is very useful in winter and summer, the dehumidified air helps defogging and defrosting and helps keep the windows clear. Without the AC, the windows can fog up with no way to clear them.

Boom!

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[diagnosticator]

Silverado and A4 are worlds apart.If your worried put a little of pag oil in.Seal the line.And leave the compressor in.In Freewheel it wount do anything either way.Waster of time removing it if you ask me.As for the belt here you go:


Gates K060450
Dayco 5060450
Napa 25-060450
Napa 25060450
Goodyear 4060450
Bando 6PK1143

IIRC you need to remove the idler thats it.

I ran the shorter bypass belt, Gates K060450 for awhile, and the idler is necessary. The smooth side of the belt runs against the idler and the tensioner, the ribbed side runs on the crank pulley, power steering pulley and alternator.

Other that running a shorter belt, the compressor is designed to retain lubrication oil in a reservoir inside allowing the compressor to be lubricated with no R134A in the system. Without refrigerant pressure in the system the compressor is locked at effectively zero pumping output position.

[diagnosticator]

The constantly driven compressor on our Audis is designed with an internal oil reservoir that holds lubricating oil inside the compressor. This provides compressor lubrication when there is no refrigerant circulating in the AC system. The presence of lubrication oil in the compressor reservoir assumes that the lubrication oil has not escaped from the system from any leaks however. If the compressor has be running with an open system, there is no way to know if there is enough lubrication oil in the compressor to lubricate it properly with no R134A in the system.

I have run with the bypass belt, Gates K060450 for awhile, and the idler pulley is required. The bypass belt fits properly with the compressor installed. The smooth side of the belt runs on the idler pulley and the belt tensioner. The ribbed side runs on the crankshaft pulley, power steering pulley and alternator pulley.

The cut AC line can be repaired for a lot less cost than $300. With the line repaired, the system can be recharged and the AC function restored. As noted before, having a functional AC system provides important benefits in winter as well as summer. The automatic Climatronic HVAC system will not work properly without the AC system operational.

[Kevin C]

The constantly driven compressor on our Audi's is designed with an internal oil reservoir that holds lubricating oil inside the compressor. This provides compressor lubrication when there is no refrigerant circulating in the AC system. The presence of lubrication oil in the compressor reservoir assumes that the lubrication oil has not escaped from the system from any leaks however. If the compressor has be running with an open system, there is no way to know if there is enough lubrication oil in the compressor to lubricate it properly with no R134A in the system.

There are examples on the forums of this not being true, the compressor exploded shortly after being run with the refrigerant discharged. There are more than enough examples of the compressors failing on closed systems, why would this ever be a good idea?


Good one on a B7:

Hi all,

Can it cause the A/C compressor to fail if I run the car without refrigerant in the system? My compressor is making a rattling noise since yesterday and I don't have refrigerant in there since few weeks.

Benthley manual says that these kind of compressor has not clutch and that we should avoid to run the engine over 2500RPM

http://www.audizine.com/forum/showth...ut-refrigerant



While the Bentley says you can run on the internal reserve on the B6, they backtracked on that for the B7. Probably because it doesn't work very well.

http://www.audizine.com/forum/showth...p-this-weekend

Example of a B6:

Driving down the road at 70 when I hear a pop and all of a sudden I see a white looking color billowing out the back of the car like crazy and all of a sudden my car shuts down. My thoughts were, great I blew my engine again at 1500 miles. Stop the car and look around and see a greyish fluid caked in metal all over the drivers side engine compartment. Since I could not see the green color from the freon I thought I had blown a rod through the block or something. Get towed home and started working on the problem. The serpentine belt wheel on the compressor seized frozen so the serpentine belt would not spin which is why my engine shut down. There was zero pressure in my ac system so that crap got everywhere when it popped.

Empty of R134, green everywhere from the oil but it still blew up?

[diagnosticator]

There are examples on the forums of this not being true, the compressor exploded shortly after being run with the refrigerant discharged. There are more than enough examples of the compressors failing on closed systems, why would this ever be a good idea?


Good one on a B7:






http://www.audizine.com/forum/showth...ut-refrigerant



While the Bentley says you can run on the internal reserve on the B6, they backtracked on that for the B7. Probably because it doesn't work very well.

http://www.audizine.com/forum/showth...p-this-weekend

Example of a B6:



Empty of R134, green everywhere from the oil but it still blew up?

I know Kevin, the compressor is supposed to retain lubrication in a reservoir as designed, but there is no way to know how much oil is in the compressor. Particularly a system that has lost refrigerant.

That is why I ran with a bypass belt before I could get my new compressor and system recharged. A new Denso compressor is filled with the total system requirement of oil from the factory, but even then I did not trust the compressor to run without R134A.

[jacobsen]

I know Kevin, the compressor is supposed to retain lubrication in a reservoir as designed, but there is no way to know how much oil is in the compressor. Particularly a system that has lost refrigerant.

That is why I ran with a bypass belt before I could get my new compressor and system recharged. A new Denso compressor is filled with the total system requirement of oil from the factory, but even then I did not trust the compressor to run without R134A.

So there's no way to know how much oil you have in your system? I added some Ester oil when I recharge my system. I just added like a third of the bottle. For that very reason that I could not tell how much was in. Now I'll say that that's something they need to design in the system, a way to tell how much oil is in it.

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[diagnosticator]

So there's no way to know how much oil you have in your system? I added some Ester oil when I recharge my system. I just added like a third of the bottle. For that very reason that I could not tell how much was in. Now I'll say that that's something they need to design in the system, a way to tell how much oil is in it.

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If you just added oil of course you would know at least how much oil is in the system. Most of the time, after running the system for a few years or longer, it is not really known for sure. If the AC system has been flushed, then the specified amount of oil added then recharged with R134A, that is the only situation where it is known exactly how much oil is in the system.

[DeViLz x DeMoN]

The system shouldn't let you run it with no gas. There are pressure sensors that will not allow pressure activation. The AC is activated by an electromagnetic clutch engaging the drive of the compressor. So when the compressor is not engaged the pully just free wheels. So you should be okay to leave it just as basically an idler pully. But if it is a continuous run system then this may not apply haha

[jacobsen]

The system shouldn't let you run it with no gas. There are pressure sensors that will not allow pressure activation. The AC is activated by an electromagnetic clutch engaging the drive of the compressor. So when the compressor is not engaged the pully just free wheels. So you should be okay to leave it just as basically an idler pully. But if it is a continuous run system then this may not apply haha

There is an internal solenoid that opens not a magnetic clutch. It spins all the time to keep the moving parts lubricated.

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[DeViLz x DeMoN]

There is an internal solenoid that opens not a magnetic clutch. It spins all the time to keep the moving parts lubricated.

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Oh okay. It must be one of the ones with the swashplates that can vary the output of the compressor. So when there is no demand on the AC system it just displaces little to no gas. And on high demand it displaces a lot more gas. In that case you would want to do the delete for compressor. As there is no gas in the system. And some of the lubricant will have escaped. Plus moisture getting in. It probably would eventually seize up.

[john_gonzo]

Oh okay. It must be one of the ones with the swashplates that can vary the output of the compressor. So when there is no demand on the AC system it just displaces little to know gas. And on high demand it displaces a lot more gas...

Yep, like this: Air-conditioning-compressor-swash-plate-vs-clutch

[leightonw]

Bypassed:) Just got done with the timing belt too at 134,760 miles.

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