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Air-Con troubleshooting advice please

easttorks964cab

Well-known member
Joined
2 Jun 2008
Messages
163
Hi Guys,

my aircon hasn't worked for a while, so I decided to gas it up and see if she would fire up.

so its now gassed, when you switch aircon on, the compressor (I presume) kicks in, which you can hear and also the revs raise and the blowers go full tilt.

Unfortunately, no cold air! any advice at what I should be looking at next?


UPDATE::
It seems that the compressor clutch isn't engaging. you can spin it manually, so its not seized, but it doesn't spin when aircon is turned on.
ive checked the fuse, which is fine.
cheers
Chris
 
I think the next step really is to have a tester connected and look at the fault codes and values for the sensors ..

ie if a sensor is reading too cold for the interior then the car wont switch the A/C on .
 
Demort, just the man! I see in my Porsche bible that there is a relay on panel 2 for the air con compressor. it says this is at the rear of the passenger compartment. is it under the carpet behind the back seats? do you think this may be at fault?
 
Ok .. i just had to refresh myself on the system , they are all different and im old lol .

The relay on a coupe is behind the seats as you said .. do i think its this though .. hmm .. no .

It COULD be but ive never changed one for this system not working ..

My guess is its the interior temp sensor that is reading wrong and youll need a tester to check this , there might be a resistance chart for it somewhere but im afraid i dont have one .. it would be something like 100 ohms at 20 degrees , 150 ohms at 30 degrees etc etc .

This should be fitted behind the round dash trim on the left side of the dashboard , i belive later models and theres one in the Heater panel behind some small vents ( not sure what model or year you have )

There is also another sensor for the outlet temp that could also be faulty and the outside temp sensor in the o/s/f duct for the radiator.

Finally you also have the pressure sensor , rare for this to give an inaccurate reading but always possible .

For me i would connect a tester , check for fault codes then look at actual values , i would expect it would be an obvious fault and take 10 mins to prove what wasnt working .

I could also say at that point that if they where all ok on the tester ( which i doubt ) then your into a wiring or control unit fault which would be a bit involved to find .
 
that's great, it gives me a positive line of attack when I take it to the garage anyway! thanks again.
 
Just a question after rereading your fault .. the revs will raise even if the a/c system isnt working so thats normal but you say the fans run at full speed ?

They should only run at slow speed so thats a bit odd if thats the case .
 
As an update, it may help others......

It turns out the gauge on my gas very quickly leapt to the green"charged" reading, making me think it was now ok. so I simply kept adding gas until, lo and behold, the compressor kicked in and all is now fine.
 

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