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Heater Blower Query

Darthmjh

Well-known member
Joined
22 Aug 2017
Messages
103
Hi,

I was using the heaters in the 993 today and noticed the screen defrosts quicker with the blower on drivers site (RH) than the passenger. Putting my hand over the screen vents I can feel it stronger on the driver's side.

Also, strangely the centre vents show similar characteristics but are more pronounced. If I open both centre vents the driver's side is a lot more powerful and I cannot feel much from the passenger side. If I close off the drivers vent I can then feel the passenger vent. I thought they were joined, obviously not!

Is this normal? If not, any ideas what it can be?

Thanks for looking

Mike
 
I guess you have a problem with one of the mixer valve servos.
This is a common issue, there's servos in both foot wells that regulates the hot air flow for the left and right side of the dashboard. The servo motors wear out and the vent might be stuck, resulting in a lower air flow on one side. See details here: https://www.bergvillfx.com/porschehvac1

These servos must be changed in a new part or refurbished in order to correct this problem.

Cheers,
Tore
 
My word Tore, that's a quick reply.

Do you have 'heater blower' as some kind of key word alert to get you scrambling to your keyboard!

:)

On another note, the remote central locking I had from you for my 964 is brilliant.

:thumb:
 
Thanks PeterS.

You could turn the temp knob to minimum, if the air flow then behaves normally you have a mixer servo issue indeed.

However, there will be a difference between the two centre vents, the air flow isn't the same on these. This is due to the HVAC air box construction.
Cheers,
Tore
 
Thanks for the advice Tore. My car a 1995 pre varioram. Interestingly from what I have read post 96 cars, the servos are under the bonnet.

Mike
 
The 993 have the Defrost, Foot Well and Fresh Air servos in the luggage compartment, under the windscreen. Both Mixer servos are behind the carpet walls in the foot wells.

The Porsche 964 and (some of) the 1994 993's have all five servos in the luggage compartment.

Cheers,
Tore
 

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