Hot under dash

por9116 · 08-26-2011, 06:44 PM

1985 - 911 coupe
After car warms up, excessive heat under drivers side dash. Hood release handle becomes too hot to touch. Oil temperature remains normal. Any thoughts?

DRACO A5OG · DRACO A5OG's Garage

Check Heater Lever that is is all the way down, if so then check the Flapper under car driver side. If it is not open all the way, you getting unwanted heat from engine.

Raise her safely and have a helper raise and lower the lever check that the flaps open and close properly, if not adjust. The nut may be rusted so be warned. While you are under there check the passenger side. That one may be functioning properly so use it as an sample where the driver side should open and close.

por9116 · 08-27-2011, 08:02 AM

Thanks for the response. So now here is the rest of the story.. Just before I put the car up for the season last year, my driver's side foot blower burned up so I removed it. I checked the other one and found it had burned up previously (before I acquired the car) so I removed that one as well. I guess I failed to realize that even with the heater off, there is a tremendous amount of hot air blowing up through the open duct (inlet to foot blowers - no longer installed) with the car in motion. Is that normal? Appears to be the same amount of heat on both sides entering the car. With the floor cover in place, the air got so warm behind the panel that it made the hood release handle heat up. Now when I turn on the Automatic heater control I get even more heat blowing up through the vent (as expected)

So the questions I have are as follows:
Is is normal to have that amount of hot air continuously blowing up into the car with the heater controls turned off? As I said before it only blows in with the car in motion. Since the engine compartment blower is providing the heat (via heat exchangers) I would have thought continuous heat coming into the car regardless if the car is moving or not but only if called for by the temperature control unit.
Do You think my servo control linkage is screwed up?
Is that the linkage that operates the flappers under the car that you were referring to?
If so, where exactly are they located?

Thanks,

Pete

DRACO A5OG · DRACO A5OG's Garage

No that is not normal, it appears from your description one of two things as I wrote. Lever may be lodge up causing the switches with the yellow wires to turn on the engine compartment heater blower or the flaps below are closed when they should be open with the levers down.

Best thing is to make sure the levers are all the way down, sometimes they bind up just enough to engage the switches when you pull the E-Brake. I am constantly checking my levers are down so I do not get unwanted heat in the cab. Just OCD like that :-)

If not, then it must be your flaps, They should be open. Those flaps tend to rust up and the cables may have rusted or stretched. You can replace them with nickle plated steel cable found at ACE hardware or get the OEM type from our host, pretty simple fix/

I would also try to service the foot blowers and place fuses on them to insure they will not burn out ever again.

Jim

por9116 · 08-28-2011, 06:16 AM

So I checked both of the flapper boxes for correct position. With the automatic temperature control switch (between the seats) in the “0” off position both flappers are fully open. When the switch is moved to the “1” thru “3” (blue) positions and “4” thru “6” (white) positions, nothing happens. When the switch is taken to positions “7” thru “9” (red), the servo linkage begins to move and the engine compartment blower turns on. At the max heat position (equivalent to “10") both flappers are fully closed. Although I may have to do some minor potentiometer adjustments, it appears that this part is functioning correctly. Note: I did take the opportunity to lubricate the flapper boxes when I had the car up on the ramps as they were definitely showing signs of corrosion.

I reinstalled the burnt out footwell blowers and connected up the hoses to close up the direct path for hot air entry into the cabin. This helped some, but with everything connected properly, the hot air now blows in through the side vents albeit not as much as through the open hole. As I mentioned previously, this only happens with the car in motion. The faster I go the more air that blows in. But with the flapper boxes open and the engine compartment blower off, it makes no sense. If I dial up the heat to turn on the engine compartment blower I get even more hot air regardless if the car is in motion (this obviously makes sense).

So any other thoughts? Also I’m not sure what you meant by checking that your levers are down next to the E- brake. Are your levers the equivalent to my temperature dial switch?

86 911 Targa · 08:53 AM

Quote:

Originally Posted by por9116

So I checked both of the flapper boxes for correct position. With the automatic temperature control switch (between the seats) in the “0” off position both flappers are fully open. When the switch is moved to the “1” thru “3” (blue) positions and “4” thru “6” (white) positions, nothing happens. When the switch is taken to positions “7” thru “9” (red), the servo linkage begins to move and the engine compartment blower turns on. At the max heat position (equivalent to “10") both flappers are fully closed. Although I may have to do some minor potentiometer adjustments, it appears that this part is functioning correctly. Note: I did take the opportunity to lubricate the flapper boxes when I had the car up on the ramps as they were definitely showing signs of corrosion.

I reinstalled the burnt out footwell blowers and connected up the hoses to close up the direct path for hot air entry into the cabin. This helped some, but with everything connected properly, the hot air now blows in through the side vents albeit not as much as through the open hole. As I mentioned previously, this only happens with the car in motion. The faster I go the more air that blows in. But with the flapper boxes open and the engine compartment blower off, it makes no sense. If I dial up the heat to turn on the engine compartment blower I get even more hot air regardless if the car is in motion (this obviously makes sense).

So any other thoughts? Also I’m not sure what you meant by checking that your levers are down next to the E- brake. Are your levers the equivalent to my temperature dial switch?

Here's a picture of a "fully" open butterfly with a broken cable.

Please compare the picture to your "fully" open butterfly.

Also, your servo unit has been trying to pull rusted cables,
which might have put excessive stress on the motor.

The existing cables can be removed and lubricated,
however, as per the previous post, I would replace them.

Check my post "Added Fuses and Relays".

pm me as needed.

Good luck,

Gerry

por9116 · 08-28-2011, 09:08 AM

The butterflies are as open as open they can be (just like your picture). When I finally get around to replacing the footwell blowers I will definately install additional fuses. Thanks. That is of course, as long as I can solve my excess heating problem.

86 911 Targa · 08-28-2011, 09:10 AM

Quote:

Originally Posted by por9116

The butterflies are as open as open they can be (just like your picture). When I finally get around to replacing the footwell blowers I will definately install additional fuses. Thanks. That is of course, as long as I can solve my excess heating problem.

Please add fuses to your dash lights, condenser/evaporator blowers ect... per my post.