I have a probelm with the temperature inside my 964. When the temp setting is put to the min & the blower is off, heat is still coming out of the vents. The Porsche mechainc says I have a problem with the 'mixer'. He say's I need to replace part # 964 624 324 00 ('Mix flap motor') He said it is a common problem on the 964.

Is there one for passenger & drivers side? How difficult is it to replace? Could I do myself & how much is this part?


Thanks in advance for any recomendations/advice.

 

Alright, Tokyo! Would you be an ex-pat living in Tokyo, or Japanese? We were discussing Japan and Porsches recently on the 993 board:

Porsches in Japan Thread

To your question. Yep, this something you can do yourself. If you're having problems with heat coming out when it shouldn't, it should be limited to one side. As you suggest, there's a mixing servo motor for each side of the dash.

It's very easy to check all your servos for proper operation. Simply remove the flimsy black plastic cover inside the trunk, base of the windshield. Play with the controls on your climate control unit (CCU) until you can see each servo operate. For example, the mixing servos should reposition when you go from a cold setting to a warm setting. On the affected side (always hot), you may find that servo does not reposition.

There's a fabulous DIY on this subject, on John M.'s 964 site, written by Rennlist's own Roly Baldwin:

HVAC DIY

The part # you were given for the mixing chamber servo is correct. I think the servo motor is somewhere in the neighborhood of $80-100.

 

Thanks Randall for your reply.

I'm an expat living in Tokyo. I just had a look at the link you sent re the discussion of Porshces in Japan. Yes, Porsche & Ferrari are huge here.

There are a great number of 964's here, not sure why, possibly because of the bubble in the late 80's/early '90's & Japan picked up for weeker demand in other markets. I usually always see another 964 when I take mine out for a spin.

 

Absolutely can't fault the choice of your 2nd car. Been hankering after one of those since a Bagheera lived at the end of my road 25 years ago

 

Tok,

Check out the recent post "hvac woes". Three of us had the same problem and each fixed it on our own! There's plenty of good advice here.

No pressure!

 

I use the info here : http://www.porsche964.co.uk/technical/servos.htm
And repaired my servo unit today. It was about a 5-10min job to repair (I had to rebend the little contacts). It is easy to test by putting 12V to terminals 4 & 5 (the top two) and seeing if the servo moves. Switch the wires and it should run the other way.

john

 

>Absolutely can't fault the choice of your 2nd car. Been hankering after one of those since a Bagheera lived at the end of my road 25 years ago

Roly, these are great cars. As you're probally aware the Murena had the Galvinised chassis, fiberglass body, mid engine lay out, good looks, cheap to buy a good one now, availability of cheap parts of the Talbot shelf & the best thing nobody knows what it is!

Thanks for all replies re heater fix, pressure is on!!

 

Having a sudden heater prob on a RHD 89/90 C4 in Scotland - have read the other postings which are v useful, but not solving my problem.

UNtil last weekend, all heater vents working great and quickly from start up - hot and controllable both sites and screen .
Saturday - virtuall zero heat from any. 3 deg Arrrg. Sunday, heat in passenger side ok, cold to drivers.
Read threads re 4/5 servos in boot - all seem to work ok on checking re control panl moves - assumed I would find the ones feeding driver side U/S - not so.

Rear blower seems to work (comes on with ignition on, fuse is ok

Confused.
Have just cleaned thermo sensor for good measure - about to refit.

Any ideas?.

 

Dear Ian,
If you believe your mixing chamber temperature servos to be functioning the only other item is that heat is not getting to them.
I would advise you switch on the defrost and let it run for some time. If that never gets hot then you have a supply of hot air problem.
Your differential pressure valves on the heat exchangers could be frozen.
Check that the rear blower IS running. Start engine, turn heat to red dot position, get out, open up engine lid and confirm it is running.
Ciao,
Adrian
964C4

 

Adrian,

Thanks , will test defrost

Had assumed heat coming to passennger side would imply the upstream fans/ valves working ok.

But guess that might have accounted for the v low heat first symtom....

Is the rear blower at engine not on as soon as the ignition is on (sorry am new to this)


How do you check the ht exchanger valves?

Ian