A/C 200q 20v

Bernie Benz b.benz at charter.net
Wed May 26 18:16:09 EDT 2004

Tom, that's one hell of a vacuum pump if it will pull 29 psi of hard vacuum!
One of a kind!  Don't fix what ain't broke, Guys.


> From: TooManyAudis at aol.com
> Date: Wed, 26 May 2004 17:29:24 EDT
> To: mdeltergo at hotmail.com, 200q20v at audifans.com, quattro at audifans.com
> Subject: Re: A/C 200q 20v
> Hi tom,
> I am looking at the same repairs to bring my 200 in to the R134 era.  Can
> you tell me what you did to your system and how much it costs.  I am looking
> at $450 to repalce dryer and recharge system with no guarantee of no leaks
> later.  They claim that they need to rechrge the sytem, them do the dye test
> for leaks.  Any insight appreciated.
> Mike
> Mike,
> I usually follow the approach that I would rather do the repairs myself,
> unless it is something that I absolutely don't want to touch.
> Items needed:
> Receiver Drier -- $35 to $40 Autozone had one that worked.
> Vacuum pump - $125 off Ebay or pawn shop
> Manifold and guages -- $50 off ebay or pawn shop
> Low Side and High Side Fittings -- $15
> Oil and R-134A -- $25
> Filling hose and connector -- $10
> Before I replace anything, I usually vacuum out the system and test if it
> holds a vacuum.  This will tell you if you need to track down leaks.  Leaks
> are 
> most common at the compressor, switches and joints betweens hoses.  If it is
> oily and dirty, you've got a leak.  You may be able to simply tighten the
> joint 
> or switch, but you will most likely have to replace a seal.
> The receiver/drier is located under the plastic shield between the firewall
> and the windshield.  You need to remove a wiper to get the plastic tray off.
> Removing the Receiver/Drier requires a couple of large wrenches or vice
> grips.  The tricky part comes with the clamp that holds the unit down -- you
> need a 
> 1/4 inch socket wrench and it is a tight fit.  I had to be creative and do
> some manuevering, but it was manageable.
> Look in your Bentley to see if you need to get the orifice tube out and clean
> it.  I didn't do this, but I wish I had, just to eliminate it as a possible
> problem area.
> Place the receiver/drier back on, then use new 134-A fittings over your
> existing service ports.  Low side is attached to the compressor.  High side is
> beside the condensor.
> Vacuum for at least an hour.  I then leave the guages attached and walk away
> for an hour or so (overnight if possible).  If there are any leaks, they will
> show up by then.  This isn't to say that just because your system holds vacuum
> that you are all set.  there's a big difference between -29 lbs and 250 lbs
> (or more) of pressure.)
> At this point, a pro shop should flush the system of any R-12 residue and
> oil.  I've never taken this step, and have had systems working for 4 and 5
> years 
> later, so to me, it's optional.  Then again I am having a few problems now,
> but I think it's unrelated to this step.
> If you have no leaks, fill with oil, then with as much 134-A as the system
> can take.  Then, jump the low pressure switch (right by the receiver drier),
> turn the car and fill system until it get up to 30 lbs or so on the low side,
> then check to see if your temps out of the vent are acceptable.  More
> refrigerant 
> doesn't always mean better cooling.  Make sure your high side isn't too high
> at this point.  You basically want the least amount of refrigerant to make the
> system run properly.  There should be a chart in the Bentley telling you the
> proper vent temps and pressures at given outside temps.
> A good estimate for R-134-A is to use 80% of the amount listed on the car for
> R-12.
> The other alternative is to use Freeze 12 instead of R-12.  I did this with a
> van at work, and there had no problems.  The advantage is that you don't have
> to flush the system or change oil with Freeze 12.  Some people just top off
> with the Freeze 12 with the remainder of the R-12 left from when it was a
> working system.  I don't know if I would do that or not.  Others on the list
> probably have more experience in these things than I do.
> That's a down and dirty overview, and certainly not the only one you'll get.
> Let me know if I can help.
> -- Tom
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