Cheeksyboy

I've read through several threads and can't find an answer to my problem which is this:

with heating set to max I get very little, barely luke warm air, coming through the vents. I've got Billy Boat complete exhaust system and I've checked the heater tubes from the headers (manifolds to UK readers!) which go to the control flap just inside the wheel arches and they're fine (i.e. no holes, tears or leaks) as far as I can tell. The two blowers mounted in the bulkhead also seem to be functioning normally as do the control motors which open and close them for cold air mixing. I've also checked the two heater tubes in the cabin footwells and they're similarly in good condition.

The cold air flap that is controlled by the button on the heater control is set to closed (and it is) and the aircon is switched off.

In addition to having very little warm air when I decelerate (whether from high speed at a rapid rate, or more slowly in normal traffic) I get a strong smell of exhaust gasses and figure this must be related.

Any ideas?

Computamedic

You didn't mention the most important part of the equation - the rear blower. If the rear blowqer isn't running (it should start pretty much as soon as you turn the heat control off the blue dot) there will be virtually no urge to the airflow through the heat exchangers. Usually, if this is the case, the cabin blowers will be stopped by the CCU but it's worth checking anyway.

Usual culprits with the rear blower are (1) the fuse, (2) the relay, (3) the ballast resistor and, finally, the blower motor itself.

A strong smell of exhaist gasses might imply that your exhaust manifold is leaking a little or the heat exchangers have a leak and are sucking in exhaust fumes.

Regards

Dave

Cheeksyboy

Thanks Dave,

I have checked and the rear blower is working fine (just replaced it acrtually as the old one's bearings were making an awful racket).

As for the smell, thanks for that idea, I'll have to have a better inspection to see if this is the case...hope not as returning them will be a pain !

Computamedic

OK - the next thing to check is the diverter flaps.

If you leave the CCU set to "heat", turn off the ignition and close the door (windows all closed). Do you hear the metallic "rattle" as you close the door??

If not, there is a chance your diverter flaps are lodged in place. Under these circumstances it's likely that the majority of the hot air from the heat exchangers is being diverted out into the rear wheel wells. If the engine is pretty warm you woulds likely be able to feel the hot air blast coming from there with the engine and rear blower running.

I have seen reports of the flaps becoming jammed although I think it's pretty rare.

Regards

Dave

Cheeksyboy

Not heard any metallic rattle (would've probably tried to cure it!) as I close the door and funny you should mention it but I have noticed the passenger side wheel well being a strong source of heat (mine's LH drive). I'll have a look at that then and let you know. Thanks for the advice.

jimq

check to see if the servo motors are opening the mixing chambers. Mine only will work part way after i tried to repair them. For Florida its plenty but I really need to get new ones.

Kahdmus

Jim, have you removed them, clean and realigned the metal contacts etc?

Cheeksy, it really sounds like the rear blower...you positive the fuse (located in the secondary fuse box in the engine bay) is good? When I had this exact problem the wire going to the rear blower had come lose and was dangling...hard to see and took me hours of fuse testing etc. before i worked it out!

jimq

Temporary Hijack but sort of related
yea 2 or 3 times. I even swapped parts between them. They will work fine for a couple of days then start partially openiing after then. They work fine for the little cold weather we get here.

Livefreeandrive

Cmedic, Thanks for explaining that "rattle". I thought something might be wrong? BTW: It sounds like a metal spoon being dropped into a coffee can.
Steve

breale01

I still feel new to all this 964 stuff, so pardon my ignorance. I too have no heat. I do hear a fan start however, when I turn the **** off blue. All the above is great info for troubleshooting, but it would be great to have a diagram showing all the motors, vents, flaps, ducting etc, to better understand the system. Anybody know where best to get one?

DarrylH

I saved these from ? Jason Andreas, hope he doesn't mind.

breale01

Wow! Now for the next question....is there a legend for what all the numbers are?

DarrylH

I've never seen one. But if you think through how the system works, you can figure out what's what. Just start at the back of the car, at the rear blower (#6), and follow the airflow...

breale01

Thanks, I'll give it a try. By the way (perhaps another newbish question), but who is Jason Andreas?

Rocket Rob

JasonAndreas is a regular contributor here. You can search and find him.