I picked up a 2009 997TT last week and 45min after driving it the AC went out. Air was blowing ice cold at first, then it just quit. No weird sounds or anything. I had a local indy take a look at it and they concluded that the compressor was likely bad. They wanted to charge me almost $2k just to replace the compressor and recharge the system. But after looking at it, this looks to be a fairly simple job. I consulted the workshop manual and it seems straight forward but I know there will be some inevitable annoyances with replacing it. Does anyone who's done this before have some advice for me? What should I look out for? Any little tricks to speed it up? I'm pretty handy with a wrench and did almost all the repairs to my 996 carrera with ease.

Also, I am noticing some different part numbers concerning the compressor. Porsche lists the correct part as 996.126.011.BX, however I see many parts listed as compatible that have different numbers at the end. Such as 52 instead of BX. Is this just a revision number? Are these parts still compatible? If so, I may have access to a spare compressor from another 997 that could potentially save me a few bucks.

 

I have an A/C compressor if you need one. I removed the A/C system from my car and have all the parts... The last two number often change and indicate revision parts.

 

Dang I wish I would have seen this sooner. Thanks anyway though. I got one cheap out of a 07 Carrera that had 18k on it. Its also warrantied for 30 days. When you pulled yours out did you have difficulty with anything? I just know with any German car, there is usually way more to it than the workshop manual implies. (For example: I replaced the door handle spring mechanism last night, no where did it mention I had to strip the door down all the the way to the door lock mechanism to replace the cable. Which included disassembling the window regulator motor.)

It appears to be just removing the airbox, accessory belt, intake tubes, and part of the throttle body assembly. This should grant access to the 3 bolts that secure the compressor the motor. Then removing the AC lines and the fuel cooler lines to completely remove it from the car. Seems simple...but...you know. Famous last words and such. :-)

 

At $2K for a new A/C compressor I'd want something a bit more definitive than "likely" bad.

The behavior doesn't necessarily suggest a bad A/C compressor to me. There are enough other explanations for the loss of A/C cooling and a bum A/C compressor is down on the list.

Up to you of course but I'd spend some money to have this properly diagnosed.

If the A/C compressor has to come out I think the proper procedure is to evacuate the system of refrigerant. Some oil is likely to be removed too.

After the system has had all its refrigerant removed and there is no low or high pressure in the system the lines are disconnected and the new compressor fitted then the lines connected. I do not know if any seals/o-rings should be replaced at this time.

Afterwards the system is again evacuated and held at a very low vacuum for a length of time to remove any moisture that might have gotten into the system -- via being exposed to atmospheric air -- and to check for any leaks.

After the system is deemed leak free then the required amount of refrigerant is added to the system along with the compressor oil that was removed, plus some extra that was lost when the compressor was replaced.

To ensure the system has the right amount of oil the factory manual has a chart that gives for every component in the system how much oil this component represents when it is replaced.

(With a used compressor I'm not sure how one knows if the unit has some oil and thus no extra is required or perhaps this oil has been allowed to drain away and some additional oil should be added to ensure the system has the right amount of oil in it.)

After all of the above the system is tested to ensure it blows the right temperature of air based on the ambient temperature and the system fittings disturbed during the compressor R&R are leak free.

 

UPDATE:

I tested the old compressor clutch with an external battery and confirmed that it was not engaging. Once I knew the clutch was bad, the decision to replace the whole thing was easy.

I really should have made a DIY, but it was hot as hell out there (it is Texas after all) and I wanted to finish the task in a reasonable amount of time. The process was fairly simple. Remove airbox, intake tubes, and throttle body. Then remove the lead for the compressor clutch, remove 3 bolts holding the compressor to the engine, disconnect the 2 I/O AC hose lines (one on the compressor, one on the right side of the engine bay) After that the compressor lifts right out with a small degree of wiggling. Then you remove the hoses from the old compressor, reinstall them on the new one, and reinstall everything. Pretty simple. I also replaced the expansion valve, drier, and all associated O-rings that go with these. Once I had it all back together I took the car to a local indy shop and had them evac and recharge. The left it on vacuum for a good while and informed that it was holding pressure perfectly. For each component removed you are supposed to replace 1 oz of PAG oil. The compressor already a small amount and since the system wasn't evacuated ahem "properly" while it was still pressurized (yeah I know, don't flame me) there was probably some still in the lines and in the condensers. I chose to add 2.5oz to the system.

edit: There was much consulting of the various online shop manuals, forum threads and multiple parts diagrams during this process. While they were indeed helpful, I think I am going to invest in the full workshop manual in the future for more involved repairs. Its never smart to do these things blind after all. The system has been blowing cold and flawless since. Very satisfied.

Costs for all of this not including my time:

AC Compressor (Used from 07 Carrera with 18k miles): $138
AC drier, expansion valve, temp sensor and O-ring kit (this also includes a new accessory belt that I replaced since I was in there anyway): $126
Evac & full recharge from indy Porsche shop: $165

Total: $429 and I learned a ton about my car. ;-)

 

More expensive to have lunch here in Miami... $429.00 I'd pay that bill with a smile!