Skidog214

This vehicle is new to me, so this is my first winter with it. It is getting cold, so I am starting to use the heater. When I turn the red rotary **** between the seats, nothing happens.

When I pull-up the yellow levers, I can feel the heat. It sort of “wafts” from beneath the dash and can get REALLY hot. I fear it could damage some wiring inside/under the dash! I can also hear a very faint blower—-maybe from the engine compartment.

The levers on the dash work fine. When I activate the fan on the dash, it works fine. So, I can direct air up and down using the dash levers and fan.

I have done some research on this forum and understand the rotary know is supposed to activate “footwell” blowers. Not sure where they are. I saw they may be protected by separate fuses. I checked the fuse box in the trunk. No blown fuses. I understand the footwell blowers may only blow when the blower in engine compartment is on. As I mentioned, I can hear a very faint blower noise when the levers between the seats are raised, so if there is a blower in the engine compartment, I think it is working, at least a little.

I also understand there may be one or more fuses in the engine compartment. If so, I can’t find them. I have looked on YouTube as well. No luck.

I have seen comments by some that the heaters work so well one can put the top down and drive with the heaters on and be comfortable. I like that idea and would like to try it, but I think there must be blowers that are not working.

So, I would be grateful for any assistance you can offer.

Many thanks to this helpful community!

Skidog214

I found a thread that described the footwell blowers with more precision. So, I think I now know where they are.
Would still like help identifying/locating the applicable fuses and relay(s).

Thanks again.

Skidog214

Engine compartment blower definitely working. So, it is just the footwell blowers that are inoperative.
Thanks

oldskewel

The footwell blower motors in my '85 cab were dead. You are right about heat being good enough to drive at night with the top down, which is nice. And I think that also means the cab blowers burn out before others do, since they get a lot more work due to this. In a coupe, you'd not use the heat so much since it would cook you.

I recommend you go straight to the footwell blowers. They're in the outboard sides of the footwells, behind carpeted panels. A few screws to get the panels out and you will see them. Then I would apply 12V to them and see what happens.

Good luck.

Skidog214

Thank you very much!

Pavegeno928

When you get them working, they are great for cold nights with the top down or to aid in defrosting the windshield.

Skidog214

How do the footwell blowers help defrost the windshield???
Btw, I have read your Griffiths AC posts and intend to install the complete system this spring.

Pavegeno928

The footwell blowers boost the output of the engine compartment heater fan and gives you much greater airflow. Note: You must have the red levers pulled up to turn on the engine compartment heater fan in order for the red rotary dial to turn on the footwell blowers and boost the output. You cannot turn the footwell. blower red rotary dial and expect the footwell blowers to come. They only work if the red lever(s) is (are) up.

Skidog214

Understood about the center levers needing to be raised to activate the footwell blowers.

But when I turn the rotary **** to activate the footwell blowers, will warm air be directed through the vents on the dash at the bottom of the windshield? Asked differently, where is air from the footwell blowers directed? Does it go through the ventilation ducts controlled by the levers on the front of the dash? Or, does it direct air through other ducts/outlets?

Thanks for your help!

Pavegeno928

Yes, it will go to windshield if the red lever on your heater/vent panel is directed to the windshield. It will go to your feet if the red lever is full towards the bottom vents, and you can mix it with the red lever on the heater/vent panel somewhere in the middle. It will also come out of the a/c vents on the dash (the four controllable vents.

Attached is a picture of the flow. Note that no fresh air (fresh air fan) will come out of the left an right a/c vents. this is an error. Also, this is for the 1986 and later so your 85 might be slightly different.

Skidog214

Interesting! Thank you!

systemsc

Be aware that the rear blower power (current from the blower motor) activates a section of the heater relay in the engine compartment, which then powers the footwell blowers.
If the rear blower or the heater relay is non-functional, no power to the footwell blowers. The heater relay can be damaged when using a faulty battery charger.

Skidog214

Where/how do I find the heater relay in the engine compartment. I have looked and do not see anything that looks like a relay. As I open the deck lid, is it to the right, left, or center? Is it inside a box or cover? How do I check to see if it is bad?

Thanks to all!

Pavegeno928

Left side under the big black plastic cover secured with a wing nut. It 's immediately aft of the fuel filter. When you take the black cover off, you will see it is protecting several fuses and relays. One of them is the heater relay. Have you downloaded the Porsche PET parts guide for your 85? It has diagrams and blowups as well as part numbers/descriptions and should help you zero in on the correct relay.

https://www.porsche.com/usa/accessor...artscatalogue/

systemsc

Here's a picture;