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996 Climate control

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I have recently purchased my 996 (1999) carrera about a month ago and have noticed the whole heating and cooling climate control system seems to be having issues. I live in the UK so this is quite a big deal. To sum up, it won't blow cold or hot.

I drove the car for around an hour at the weekend and could not get any real heat out of the system, Cranked it all the way to the highest temperature but only felt the breeze of the fan blowing round. I tried with the snow flake button on, then tried with it off, no difference at all over a period of at least half an hour.

On the other hand the temperature won't blow freezing cold. I imagine that perhaps I need to take the car to have some gas added to the system.

If it is raining outside, it is almost impossible to clear the misty/ foggy windows and windscreen. My only hope is to turn the fan speed to max and crack open the window slightly.

My first thoughts were perhaps I need to replace a heater matrix, but despite many hours searching on the internet it certainly doesn't seem like a common issue for 996 or boxster owners. I imagine it is a very similar climate control set up in both cars?

Thanks for any help here, Driving will become even more fun when I can remove my coat and scarf in the car.

Edited by ckellum84
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I could be many things, but here are some ideas.

-Take a look at he aircon compressor in the rear and see if the clutch engages, making the inner part spin. If it does not it could indicate that you are missing gas on the aircon system, because there is a shot of valve. You need 900 grams R-134.

-Check the fuse box to see if any of the relevant fuses for the heating system and aircon is blown. You can find the relevant fuses using the search function on this site.

Just somewhere to start


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What a coincidence because today my 99' 996 HVAC started acting up. It's been flawless since I've owned the car, but with the summer coming up I need to fix it fast!

It blows "warm" air even at "Lo".

And the air con is no where near as cold as it once was.

I am thinking I have an opposite problem than yours though, perhaps heater core flap or mix flap is stuck or frozen.

I haven't had time to research it yet though

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The A/C clutch was engaging, which from what I understand if there is not enough gas in the system it might not engage.

And then see this post for my solution:

Curious what the original poster found out, if anything.

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  • 1 month later...

Following on from my initial post i took the car to have the air con gassed. The pressure test revealed a leak on the driver side under front bumper. I have ordered a new condenser which i will fit this week.

Hopefully the air con will then blow cold when gassed.

Doubt this sort out the issue of lack of hot air though. Not loosing coolant so no leak in matrix. Strange.

Edited by ckellum84
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I also had ineffective AC on my 1999MY 996 C2 until recently. I also had a slow coolant leak but no obvious signs of escape.

I hoped for a cheap fix and much against my better judgement took it to KwikFit (UK) for their £49 gas recharge. When I picked it up they told me the car was now like a fridge inside. It wasn't.

I took it to my Indy (Precision Porsche) for an unrelated matter and long story short ended up replacing the rads, condensors and receiver/drier, all OEM (not Porsche) parts from design911.

My aircon now works fine - the only good news is that they declared my compressor to be still A1.

As to the cause? Lets just say I will be fitting mesh to my bumper grilles in the very near futire...

Edited by le bouch
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Today I removed my front bumper to fit my new drivers side condenser. It certainly looks like I am the first person to remove the bumper and clean away the dust dirt and leaves, but luckily there wasn't much lodged behind. Nothing compared to some other cars i've seen on these forums. I think the car has always been kept in a garage during it's life so this may have helped.

The old condenser was in fairly good condition and didn't show any visible holes where the leak may have come from. I did notice the rubber o-rings were perhaps a little perished and stiff. These rings connect the pipes to the condenser. I swapped it for the shiney new one and fitted the new rubber rings. I also replaced the two o-rings on the passenger side condenser.

I will be taking the car for a gassing next Saturday. Fingers crossed.

When I disconnected the passenger side condenser, some oily liquid dribbled out of it. Only a small puddle. Does anybody know what this if for and if should be there?

Also i'm interested to know what the yellowy coloured hose that runs to the centre of the car then connects to the black hose is? See my front image, right in the centre under the metal bumper.




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