[Pierre968]

Hello Everyone,

 

On summer back on road with my car , i noticed that my 968 is blowing hot air from side vent and lukewarm air from the front vent.

 

On running speed , it feel to get warmer.

On idle it's became cold on front vent and lukewarm from side vent.

 

Did you have idea ? 

 

Could be heater valve ? All motors and clip are working.

 

Any ideas ? 

 

Thanks.

 

Pierre 

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[MCL968]

The valve is vacuum actuated and it defaults to hot when the vacuum level is low. Start by checking your vacuum lines.

 

Mine would just go on and blow hot air at random times. I replaced the ignition switch and the problem disappeared. I noticed that when I bumped the keys with my knee when driving the heater would start blowing hot air. Strange, but the problem was fixed by a new ignition switch.

 

Bon chance!

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[Pierre968]

Hello, 


 

Thanks for your reply, you mean ignition switch on steering column ?


 

This Parts 944 613 024 01?


 

How can it be related to HVAC ? 


 

I will check vacum line also , may be the best way to start


 

I have change also heater core and all hose coming to the heater las year 


I have unbolt platisc protection under the dash and check all plastic clip , all are working like this video https://www.youtube.com/watch?v=AN96tJhDLS8

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[Waylander]

A worn ignition switch can have all sorts of weird effects, no side lights, no dash lights, no windscreen wipers, windows work intermittently

The switch feeds power to all the circuits in the car, the switch is quite a common fault



Air locks are another issue with these cars, the sound of rushing water in the heater box gives that away, always put the front left wheel up on 2-3 inches of wood so the header is higher than the engine, helps with the bleed process

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[J.Elenbaas]

Maybe it's just an broken plastic clip close to the servo that adjust the heat.

I had it once when during driving the temperature inside went sky high.

A plastic clip in the drivers side footwell at the middle console broke and the system ended up in blowing hot air only. 

It's one of the clips you see in the video at 0.37 seconds

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[Pierre968]

I made the diagnosis

 
What works:
- Clip not broken
- Check flaps
- Check little motors
 
What doesn't work:
- Defective heating valve: It stays open and does not close so the pipes are always hot inside
 
So I'm looking for the vacuum circuit lines:
- I have a Y on the injection rail and with a tube in the vacuum and the small blue black part
- Oddly enough, I can't find an air intake on the mastervac! like the schema
- Sealing of the vacuum lines circuit I do not feel any vacuum! Surely something plugged in the wrong way!
 
In fact ... On 968 there is no connection on the mastervac as in the PET show, I feel that at porsche they have taken all the pages of 944 but it is rather 951/968 the type of vacuum line.
 
I found where to go the empty air hose without vacuum line.
It goes to the injection page, which has nothing to do with the heating diagram!
 
Now The valve closes, so it works again.
 
It remains to do a road test but the residual heat from the radiator should leave once the valve is closed.
 
   
 
 

 
   
 
   
 

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[ds968]

Kudos !  Very nicely done Pierre , and also helpful diagrams and photos documentation.   

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