Potenital heater problems?

[York]

Hello all, I have an '88 3.2 Carrera LHD which may have a problem, but may be a normal Porsche 'quirk' and would welcome any advice.

It seems that no matter where I position the heater controls hot air is blown inot the cabin, which can make it very uncomfortable to drive on a hot summers day (rare I know!).

Altering the settings just seems to alter where the hot air comes from, be it floor vent/centre vents or windscreen de-misters. Is this normal?! The only solution is to put the fresh air blower on full power, which seems to mask it at least but is rather noisy, especially on the motor way with all the other noise.

Thanks in advance for any advice.


Migration info. Legacy thread was 5654

 

[James Ball]

Hi York. What you describe is normal in that it happens a lot, but it is not correct. There is a flap (in the flapper box) that directs hot air from the heat exchanger either into the cabin or into the outside world can get jammed which means that hot air permanently pours in to the car. I believe the solution, if you don't want to replace the flapper box, is to jam the flappers in the position where the hot air is released out of the system.

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[York]

That sounds about right thanks James, just one question, whats the flapper box?

Jamming them open would suffice for the summer, and make driving much more enjoyable again!






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[James Ball]

Have a look at:
http://www.pelicanparts.com/techarticles/tom_sharpes/heater_box1.htm

Cheers, James


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[York]

Brilliant, cheers for that, gives me a mission for saturday!

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[Jamie Summers]

York,

I had the same problem on my '89 - now fixed. The flaps are operated bya cable attached to the twiddly knob between the seats - over time the cable can stretch or pull through its mounting. Nine times out of ten a good bit of WD40 on the flaps and retensioning the cable sorts the problem out.


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[York]

Thanks for the advice Jamie, haven't had chance to look at it yet but am relieved it's fixable and not just one of the famous 'quirks' of 911s!

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[Mr Duncan Platt]

Hello York,I have same car 1989 year and it was the cable. AFN sorted it out ,you should also test your heater motors because they needed replacing on mine.

Duncan911


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[York]

Thanks again Duncan, have finally had a chance to check it though and the flaps apprear to be working fine.

I've completely disconected the flexible hose leading to the flaps now to ensure that the hot air cannot get through, inspired by the current heat wave!!

The hose just vents straight to air now, pointing towards the wheel area, does anybody think this will lead to problems? Don't want anything frying!



Cheers, York.


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[R1gti]

Firstly Hello, and secondly sorry to drag up and old post!

I've been asked by a friend to have a look at a similar problem with his '85 3.2 911

The difference with his car and the car in the photo's linked above, is that his heater controls are in the dash and all that is between the seats is a round knob with heat temp 1-9 IIRC

when twisting this know it feels electronic and not attached to a cable, but the levers in the dash are so and I can see them moving the cable behind the dash, I just can't follow where it goes.

I intended to look at the round heater flap mechanism today but unfortunately the owner is off out for the weekend so I only had a few minutes to look.

Is the heater flap at the rear of the car the same despite the controls being located in a different area?

Many thanks for any advice in advance

Rich


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[adrianc]

hot air....

Forget for a moment the controls sliders on the dash, all they do is direct air......

If you have continous hot air do the following checks in this order;

1. Ignition on. turn your temp control knob between the seats to full cold, do you hear a little motor running? (if not you have a problem inside the unit).

2. by sticking your finger inside the control box you should feel a lever motoring to and fro as you alter the temp from hot to cold....you do, great... this lever pulls cables which open/shut the hot air valve/flap under the car.

If the above function it means you have a problem with the cables or flaps.

What goes wrong is this;

(a) the cable or cables sieze and dont not shut off the hot air..replace them or remove, clean, lubricate.

(b) the cables get so tight that the plastic universal joint insde the temp control box breaks or drops off (connecting to the lever)...if so do as above and replace the plastic joint with new.

(c) if all the above work, and the flaps are working/free its likely that the actual flap inside the underfloor flap box/valve has rotted away and is leaking hot air in which case you replace the flap box ( known as a heater control valve).

Its simple but hard to write about and covered better in my guide.

Hope this helps diagnosis.

Adrian Crawford.
www.911secrets.com
www.performance2and4.co.uk


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[R1gti]

Many thanks Adrian,

The problem is no hot air at all, and my first guess when I first posted was maybe the flaps under the car with the aid of your guide posted elswhere. So thanks again for popping the link back up and your advice. It was this small control box in the middle that was confusing me as I couldn't find any reference to it anywhere else.

The main heater controls in the dash are certainly moving cables so it must be the other compenents that are to blame.

As soon as I have the car back I to work on I will lift up the back end and have a proper look.

Many thanks again

Rich


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[Mick Cliff]

Just picked up on this post.

I had a similar problem on my '84 3.2. After much ferreting it turned out to be two things:

One of the rose joints connected to the servo operating arm (in the 'black box between the seats) had failed. A couple of self tappers to tighten the joints cured that.

After dismantling the 'black box' I found two microswitches under the cover and realised that one wasn't working. After 'exercising' & a little WD40 it has worked perfectly ever since (2 years).

Hope this helps & good luck




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[PETER MEADEN]

Hi Guys

I have recently bought my first Porsche, 89 3.2 which I love, and have subsequently logged onto the 911 forum. I too have hot air pumping into the footwell wherever I have the heater controls. All your helpfull tips will soon be put into action

Keep you updated

Peter


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