Porsche 911UK Forum

Welcome to the @Porsche911UK website. Register a free account today to become a member! Sign up is quick and easy, then you can view, participate in topics and posts across the site that covers all things Porsche.

Already registered and looking to recovery your account, select 'login in' and then the 'forget your password' option.

air conditioning

johne

Well-known member
Joined
7 Apr 2008
Messages
289
had a new air con pump and re gas when I bought the car but it dosent seem to blow out coldish air .its only been on a year .can I get it tested ?
 
johne said:
had a new air con pump and re gas when I bought the car but it dosent seem to blow out coldish air .its only been on a year .can I get it tested ?

This can be a very expensive problem to chase around and I know this personally!! However in replacing about 90% of the system I tracked my leak down to the hoses that run in the sills. When the system is tested they place it under vacuum conditions, this itself is a prblem as my system always passed this test. The problem being a rubber bracket that the pipework runs through rubs over time, wering a hole in the pipe. When the system is put under vacuum, it sucks the rubber bracket tight to the pipe, blocking the hole. Porsche did re-design the braccket as it was a known issue. Its a rather cheap fix compared to most other options so I'd check this 1st then go through the check list of condenser, evaporator etc etc you may be unlucky and have a few leaks like myself.
 
Double post....
 
I had the compressor replaced then a re gas, didn't work. Leak then traced to pipes in the sill & possibly the evaporator. As the evaporator change is very labour intensive (petrol tank out etc) I decided to just go for the pipes (these being quite a few hundred £'s each :eek: themselves)

So far so good :D

Good luck
 
My money is on the evaporator being knackered :what: It's only a matter of time.............

If you used Meccano as a kid you could DIY. Not very technical but labour charges aren't cheap. The part is less than £100

http://p-car.com/diy/ac/

Get it tested for leaks first :thumb:
 
Pipes replaced twice, because they used the old rubbers which were coated with Aluminim oxide, a very good abrasive. now the evaporator has gone. Luckily my mate Jim who has a 993 has done one on a 964, not that he liked doing it. He reckons it's just an age thing. He replaced the pump not long ago so I may as well get the condensor done at the same time. A good right up on pelican and pcar but not a practical diy unless you have the facilities.
 
How cool is the air coming out of the dash vents? Test conditions:
About 20 degrees ambient and no sun
Engine warm and idling
Doors and windows closed
CCU settings: Min temp, max fan, Resirc on, upper slider to leftmost position. (or big snowflake button pressed)
Measure at dashboard centre vents, you should read 7-9 degrees C.

Is the A/C compressor cycling on and off at engine idle? If so, pressure is OK in the cooling system, and you do not have a leak.

As mentioned above, the most common failing part in the A/C cooling system is the evaporator. This is easily checked by a A/C technician using a electronic sniffer. They can poke the instrument through the resirculation flap under the dashboard, right onto the evap radiator.

The most common fault in the ventilation system is failing servo motors. One or both of the mixer servos may have given up the ghost, and may have stopped in the open position. Heated air from the engine will then overshadow any A/C cooled air.

Servo testing is easy, see my DIY pages.
Cheers,
Tore
 
one question why is the cold air blower stronger than when I have the air con switched on . is this normal ?
 
Most probably by a non-functioning resirculation flap.
The Resirc flap is vacuum operated, and a leak somewhere will cause it to not open fully when needed. If the cabin temperature is sufficiently higher than the desired, (temp setting) the CCU will close all other air sources (fresh air and mixer flaps) when you press A/C and rely on tdrawing air through the resirc flap only. If this is not fully open, it will limit the air volume significantly.
I guess revving the engine will affect this, with a whoomph sound or similar at high fan speeds when the flap closes due to the reduced vacuum.
Details in chapter VACUUM OPERATED RECIRCULATION FLAP here:
https://www.bergvillfx.com/porschehvac2
Cheers,
Tore
 
well I tested the car yesterday .and the aircon is deffinatley not working properly . as for fixing not to sure I could do this myself haven't the tools,time and technical knowledge .unless the replacing of the lines and new rubber holders is do able by a non professional .I can easily live without the aircon but it seems a shame to have a brand new pump and for it not to work as the car is carrying the extra weight .so any advice on who to use and a ball park figure on cost .getting the check strap done this month so it may have to wait a couple of months. I still love this car :)
 
Get the fault diagnosed first by an AC specialist using the UV dye. That way you will have an idea what needs replacing as it could be simple.

Condensor should be a few hundred, evaporator near £1k because of labour. My Indy has experience of doing the evaporator as he has done one in my 993 and then 964 :roll: so he's got it sorted and will probably do a good deal.

Where you based?
 
As said above a vacuum hold leak test DOES NOT find all leaks. We us Nitrogen to fill the A/C system and then trace the leak that way.
 
johne said:
well I tested the car yesterday .and the aircon is deffinatley not working properly . as for fixing not to sure I could do this myself haven't the tools,time and technical knowledge .unless the replacing of the lines and new rubber holders is do able by a non professional .I can easily live without the aircon but it seems a shame to have a brand new pump and for it not to work as the car is carrying the extra weight .so any advice on who to use and a ball park figure on cost .getting the check strap done this month so it may have to wait a couple of months. I still love this car :)

Replacing the pipes and rubber supports isn't difficult, once you get the near side sill cover and wheel arch liners off its fairly obvious.

The other alternative as it sounds like a smallish loss is to get the system re-gassed (£30) compressor and air-con should then work, keep an eye on compressor engagement as an indication of vacuum loss.

You won't be the only 993 owner who gets the system re-gassed each year in the knowledge that it will only last a few months.
 

New Threads

Forum statistics

Threads
124,350
Messages
1,439,419
Members
48,707
Latest member
race911turbo
Back
Top