BikePilot

My 968's HVAC system has been a bit erratic for a few months. Sometimes when I turn it all the way hot I get no heat, other times I get heat and this morning I had heat all the time (even when set to cool). I have noted an odd clicking that sounds like it's behind the glovebox at times. Not sure if it's related or what's back there, a relay maybe?

Does the 968 use both blend doors and a valve to shut off coolant flow to the heater core? Any advice on what to check first? It's still erratic and it seems like everytime I get time to do some checking it starts working normally. If there are common failure points I'd be happy to just put new bits on and take it from there.

Thanks!

shortyboy

if the 968 blower setup is like the 951, try checking under the dash near where your right knee would be. Theres an arm that holds a flapper door shut with a clip and bar. If the clip has broken off or missing the bar will not hold it shut, thus getting hot air.

konakat

It sounds like the disc valve for the heater core. It is located between the head and the firewall and is controlled by a vacuum line. They are prone to failure, but I remember seeing a thread where someone found a drop-in replacement that was made of metal and much more reliable. The OEM part is 928 574 573 03.

NoRush993/951

I had the same problem on my 951 and it was the interior temperature sensor. It is behind the glove box and can be a d.i.y. replacement. The part was NLA and I had to get a used one. $75.00
Part # 94462401300.
I got it from www.DCAuto.com in FL.

Remove the glovebox to access the sensor.
Worked perfect after replacement.

BikePilot

Thanks guys! Sounds like I need to:

1. verify whether the blend door is operating correctly (under dash by my right knee)
2. replace failure prone heater core disc valve
3. Possibly replace int. temp sensor behind glovebox

bonus12

One more thing. sometimes the heater valve gets stuck, as mentioned, but i have found that turning the heat all the way on, then all the way off, then all the way on, and so forth, can unstick the valve. sometimes it takes a couple dozen cycles. then i found that turning the heat all the way off before shutting down the engine prevents the sticking from happening again. I would use this practice on any 944, because I bet it helps keep the components of the valve in fresher condition.

That's juts one way to diagnose the valve.

If you find the metal replacement, please let us know.

Thanks and good luck.

konakat

I found the thread for the alternate heater valve.

https://rennlist.com/forums/924-931-...rol-valve.html