AC compressor replacement
08-19-2007, 03:59 PM
#1
AC compressor replacement
After my AC got noisier an noisier it finally broke! Of course living in Dallas, TX, AC is mandatory.
Turned out that the AC clutch disintegrated (compressor still ok).
Here is a picture of the broken clutch:
<img src="http://pictureposter.audiworld.com/123884/acclutch.jpg">
Shop quoted $1300 to replace compressor. Sticker shock !!
Cheapest clutch I found was $480, cheapest new compressor + clutch was $289.
Because of clearance issues (AC clutch is real close to frame), it isn't possible to service the clutch while the compressor is installed and because a new compressor + clutch assembly was much cheaper than the clutch alone, I decided to replace both.
$1000 for professional installation?! -> time for DIY.
I've never repaired anything major on a car but wanted to try to save some money. Turned out to be a fairly simple task.
Steps to remove compressor:
* remove refrigerant (at AC shop).
* release accessory belt tension by locking tensioner.
* unplug AC clutch.
* jack up car safely
* remove plastic shield from bottom of engine bay and plastic cover to expose AC compressor.
* remove accessory belt (and note orientation).
* remove screws hold metal pipe between intercoolers.
* open rubber connector between pipe and left intercooler.
* move away the metal pipe to gain access to the air pump (? - black round item right of power steering pump).
* remove power steering pump pulley (attached witch allen screws).
* unplug power steering pump (sensor ?) cable.
* remove screws holding power steering pump.
* move power steering pump out of bracket and let dangle.
* remove nuts holding air pump.
* unplug air pump cable.
* move air pump out of bracket and tuck away to the left.
this gives access to the AC compressor back, where the AC lines are connected.
* unbolt allen screws attaching the AC lines to the compressor.
* remove AC lines and plug AC lines.
* unbolt AC compressor (held by two long screws).
* use crow bar to get AC compressor out of bracket.
* don't lose aluminum spacer (will fall out).
* snake AC compressor out through the back.
Remove drier:
* unbolt allen screw attaching the inlet line on top of the drier (required a LOT of torque).
* unbolt allen screw attaching the outlet line on bottom of drier.
* unbolt bracket holding the drier.
* remove drier.
Re-install new drier (two man job and challenge because of access and clearances and upper 90s ambient temperature didn't help things):
* change O-rings and oil O-rings.
* slide drier into inlet line holder.
* rotate drier to match holder screw hole with drier threaded hole (two-people required: one to look and one to rotate and hold drier).
* attach inlet line with allen screw, hand-tighten!
* attach outlet line with allen screw, hand-tighten!
* attach bracket.
* tighten allen screws holding inlet and outlet lines.
Steps to prepare new compressor:
* drain PAG oil from old compressor and measure.
* drain oil from new compressor.
* fill new compressor with new PAG oil with amount equal to what was in the old compressor + volume held in drier.
Steps to prepare new clutch:
* replace electrical connector with correct connector (from old compressor clutch).
Install new compressor:
* snake new compressor up to the compressor bracket.
* slide compressor into bottom part of compressor bracket.
* insert screw into bottom of bracket and hand tighten. Compressor should swivel.
* insert aluminum spacer between compressor and top of bracket and swivel compressor into top of bracket.
* insert screw into top of bracket.
* tighten both screws holding the compressor.
* change and oil O-rings on AC lines.
* attach AC lines to back of compressor.
Now its time to pull a vacuum and check, if it can hold a vacuum over a few hours.
I rented a vacuum pump from Autozone. I had to call 5 Autozones in the vicinity to find one that actually rents a vacuum pump to evacuate an auto AC system.
* rent vacuum pump.
* buy R134a manifold + gauges + hoses.
* attach manifold to low and high side as per instructions that come with manifold (open all valves).
* pull a vacuum as per instructions that come with pump.
If the installation can hold the vacuum for a day after the pump is shut down, it is probably tight.
* re-install air pump.
* re-install power steering pump.
* re-install intercooler metal pipe.
* re-install accessory belt.
* re-install plastic liners/covers.
* lower car/remove jacks.
* pull vacuum for an hour or so to boil off all moisture in the system.
* put on gloves and safety goggles.
* close low and high side valves on manifold.
* attach R134a can to manifold inlet hose and pierce can.
* shake can and open valve on can.
* purge air from manifold inlet hose by opening the inlet hose schrader valve on manifold for a few seconds (close valve again).
* start car and set AC to max cool.
* open low side valve on manifold (leave high side valve CLOSED !!).
* slowly shake can to get refrigerant into system. It took some 15 minutes !? for the first can to empty completely. After a while the AC clutch engages once enough pressure is in the system.
* close low side valve on manifold.
* replace R134a can with new can.
* purge air from manifold inlet hose by opening the inlet hose schrader valve on manifold for a few seconds (close valve again).
* slowly shake can to get refrigerant into system. It took some 40 minutes !? for the second can to empty completely.
* close low side valve on manifold.
* at this point the AC blew cold and the amount of refrigerant (700g) was almost what Audi specifies. The pressures fluctuated between 30-40 psi low side and 200-230 high side.
* close all valves and remove manifold + hoses.
* done.
While the list looks long, it took only about 4 hours total in a fairly relaxed fashion. The weather was HOT (Dallas summer) so I did it in four 1 hour segments over two weekends. The most difficult part was replacing the receiver drier. I didn't flush the system and didn't exchange the TXV valve (don't know where it is in the TT but I think it has one and not just an orifice valve) because the original compressor was not damaged and cooled perfectly fine right until the clutch went.
I think $1000 saved in 4 hours isn't too bad. And it was very interesting so no regrets (so far).
Turned out that the AC clutch disintegrated (compressor still ok).
Here is a picture of the broken clutch:
<img src="http://pictureposter.audiworld.com/123884/acclutch.jpg">
Shop quoted $1300 to replace compressor. Sticker shock !!
Cheapest clutch I found was $480, cheapest new compressor + clutch was $289.
Because of clearance issues (AC clutch is real close to frame), it isn't possible to service the clutch while the compressor is installed and because a new compressor + clutch assembly was much cheaper than the clutch alone, I decided to replace both.
$1000 for professional installation?! -> time for DIY.
I've never repaired anything major on a car but wanted to try to save some money. Turned out to be a fairly simple task.
Steps to remove compressor:
* remove refrigerant (at AC shop).
* release accessory belt tension by locking tensioner.
* unplug AC clutch.
* jack up car safely
* remove plastic shield from bottom of engine bay and plastic cover to expose AC compressor.
* remove accessory belt (and note orientation).
* remove screws hold metal pipe between intercoolers.
* open rubber connector between pipe and left intercooler.
* move away the metal pipe to gain access to the air pump (? - black round item right of power steering pump).
* remove power steering pump pulley (attached witch allen screws).
* unplug power steering pump (sensor ?) cable.
* remove screws holding power steering pump.
* move power steering pump out of bracket and let dangle.
* remove nuts holding air pump.
* unplug air pump cable.
* move air pump out of bracket and tuck away to the left.
this gives access to the AC compressor back, where the AC lines are connected.
* unbolt allen screws attaching the AC lines to the compressor.
* remove AC lines and plug AC lines.
* unbolt AC compressor (held by two long screws).
* use crow bar to get AC compressor out of bracket.
* don't lose aluminum spacer (will fall out).
* snake AC compressor out through the back.
Remove drier:
* unbolt allen screw attaching the inlet line on top of the drier (required a LOT of torque).
* unbolt allen screw attaching the outlet line on bottom of drier.
* unbolt bracket holding the drier.
* remove drier.
Re-install new drier (two man job and challenge because of access and clearances and upper 90s ambient temperature didn't help things):
* change O-rings and oil O-rings.
* slide drier into inlet line holder.
* rotate drier to match holder screw hole with drier threaded hole (two-people required: one to look and one to rotate and hold drier).
* attach inlet line with allen screw, hand-tighten!
* attach outlet line with allen screw, hand-tighten!
* attach bracket.
* tighten allen screws holding inlet and outlet lines.
Steps to prepare new compressor:
* drain PAG oil from old compressor and measure.
* drain oil from new compressor.
* fill new compressor with new PAG oil with amount equal to what was in the old compressor + volume held in drier.
Steps to prepare new clutch:
* replace electrical connector with correct connector (from old compressor clutch).
Install new compressor:
* snake new compressor up to the compressor bracket.
* slide compressor into bottom part of compressor bracket.
* insert screw into bottom of bracket and hand tighten. Compressor should swivel.
* insert aluminum spacer between compressor and top of bracket and swivel compressor into top of bracket.
* insert screw into top of bracket.
* tighten both screws holding the compressor.
* change and oil O-rings on AC lines.
* attach AC lines to back of compressor.
Now its time to pull a vacuum and check, if it can hold a vacuum over a few hours.
I rented a vacuum pump from Autozone. I had to call 5 Autozones in the vicinity to find one that actually rents a vacuum pump to evacuate an auto AC system.
* rent vacuum pump.
* buy R134a manifold + gauges + hoses.
* attach manifold to low and high side as per instructions that come with manifold (open all valves).
* pull a vacuum as per instructions that come with pump.
If the installation can hold the vacuum for a day after the pump is shut down, it is probably tight.
* re-install air pump.
* re-install power steering pump.
* re-install intercooler metal pipe.
* re-install accessory belt.
* re-install plastic liners/covers.
* lower car/remove jacks.
* pull vacuum for an hour or so to boil off all moisture in the system.
* put on gloves and safety goggles.
* close low and high side valves on manifold.
* attach R134a can to manifold inlet hose and pierce can.
* shake can and open valve on can.
* purge air from manifold inlet hose by opening the inlet hose schrader valve on manifold for a few seconds (close valve again).
* start car and set AC to max cool.
* open low side valve on manifold (leave high side valve CLOSED !!).
* slowly shake can to get refrigerant into system. It took some 15 minutes !? for the first can to empty completely. After a while the AC clutch engages once enough pressure is in the system.
* close low side valve on manifold.
* replace R134a can with new can.
* purge air from manifold inlet hose by opening the inlet hose schrader valve on manifold for a few seconds (close valve again).
* slowly shake can to get refrigerant into system. It took some 40 minutes !? for the second can to empty completely.
* close low side valve on manifold.
* at this point the AC blew cold and the amount of refrigerant (700g) was almost what Audi specifies. The pressures fluctuated between 30-40 psi low side and 200-230 high side.
* close all valves and remove manifold + hoses.
* done.
While the list looks long, it took only about 4 hours total in a fairly relaxed fashion. The weather was HOT (Dallas summer) so I did it in four 1 hour segments over two weekends. The most difficult part was replacing the receiver drier. I didn't flush the system and didn't exchange the TXV valve (don't know where it is in the TT but I think it has one and not just an orifice valve) because the original compressor was not damaged and cooled perfectly fine right until the clutch went.
I think $1000 saved in 4 hours isn't too bad. And it was very interesting so no regrets (so far).
The following users liked this post:
TTMK1Love (06-27-2019)
08-19-2007, 04:08 PM
#2
My Tech replaced my AC clutch with a used one from another VW
and didnt have to remove anything but the old clutch...Now the spline set up on my shaft differed but was fixed by a little creative drilling of the new clutch splines.An cool air is good in Florida ;-)
Marcus
Marcus
The following users liked this post:
TTMK1Love (06-27-2019)
The following users liked this post:
TTMK1Love (06-27-2019)
The following users liked this post:
TTMK1Love (06-27-2019)
08-19-2007, 05:34 PM
#7
So if you've never did anything major on your TT, where did you get all these in depth and highly
detailed instructions with parts names, locations, and specifications? I believe there's something you aren't telling us...
