DIY fixing heater blower. Where to start?

[Marlon Targa 86]

Hey guys,

My next project is fixing the heater blower.

Car: 1986 Targa

Problem: when I turn on the heater, no air comes out. My mechanic took a quick look at it a while ago and said the blower/motor is fine. He suspected an electrical/wiring problem

So, what steps do you recommend I go through, trying to track down the problem?

Thanks,

Marlon

[86 911 Targa]

Originally Posted by Marlon Targa 86

Hey guys,

My next project is fixing the heater blower.

Car: 1986 Targa

Problem: when I turn on the heater, no air comes out. My mechanic took a quick look at it a while ago and said the blower/motor is fine. He suspected an electrical/wiring problem

So, what steps do you recommend I go through, trying to track down the problem?

Thanks,

Marlon

Are you referring to the engine compartment blower,
or the footwell blowers?

[cgibson67]

Have you put 12v directly at the fan to make sure the motor isn't frozen? I did that to mine last night and nothing, so I'll be opening it up this weekend and try to fix it without having to buy a new blower ($$$)

[kidrock]

If you're not getting any heat at all, I'd check the heater boxes to see if the flappers are operative. I'm assuming that you have the 2 heat levers located at the E-brake?

[initial]

The problem must be with the engine compartment blower and NOT the footwell blowers.

I have a Carrera with non-working footwell blowers and there's more than enough heat. A little too much in my opinion.

I can't imagine having working footwell blowers.

[Marlon Targa 86]

When I turn the knob on the center console and slide the levers on the dashboard, I get nothing. No air is getting pushed out of the vents and I don't feel any heat.

[86 911 Targa]

Originally Posted by Marlon Targa 86

Hey guys,

My next project is fixing the heater blower.

Car: 1986 Targa

Problem: when I turn on the heater, no air comes out. My mechanic took a quick look at it a while ago and said the blower/motor is fine. He suspected an electrical/wiring problem

So, what steps do you recommend I go through, trying to track down the problem?

Thanks,

Marlon

Marlon,

Start simple.

We don't know what your mechanic checked.

But if it is the engine compartment blower,
check fuses #1 (16A) and #2 (25A) by rotating them in
the holders (contact corrosion), and replace as required.

Good luck,

Gerry

[Marlon Targa 86]

Originally Posted by 86 911 Targa

Marlon,

Start simple.

We don't know what your mechanic checked.

But if it is the engine compartment blower,
check fuses #1 (16A) and #2 (25A) by rotating them in
the holders (contact corrosion), and replace as required.

Good luck,

Gerry

Awesome. Will do that during the weekend.

[aj88cab]

Originally Posted by Marlon Targa 86

When I turn the knob on the center console and slide the levers on the dashboard, I get nothing. No air is getting pushed out of the vents and I don't feel any heat.

Please let us know if you have manual (two red levers at center console, dial numbered 0-3) or auto heat (dial on center console numbered 0-9).

Diagonsis will be different depending on this information

By what you describe above you may not even be turning on the heat if it is manual.

If auto heat you may have a disconnected flapper control servo rod.

[efhughes3]

It's auto heat. He's got some feedback on RL based on this.

[Marlon Targa 86]

UPDATE:

I now understand the air flow system... I think?! So I'm not getting fresh air flow nor do I get hot air flow. But they originate from 2 different places.

When I turn on the ignition ( not the engine) I do hear a whirring sound coming from the center knob, which gets a little louder as I turn the knob "up".

But when I slide the "handles" on the dash, all the way to the right to 3 (or III), no air is pushed through the vents.

I checked the fuses/relay and they seems fine.

Marlon

[86 911 Targa]

Originally Posted by Marlon Targa 86

UPDATE:

I now understand the air flow system... I think?! So I'm not getting fresh air flow nor do I get hot air flow. But they originate from 2 different places.

When I turn on the ignition ( not the engine) I do hear a whirring sound coming from the center knob, which gets a little louder as I turn the knob "up".

But when I slide the "handles" on the dash, all the way to the right to 3 (or III), no air is pushed through the vents.

I checked the fuses/relay and they seems fine.

Marlon

Marlon,

Here are the manual and auto heat controls.

If you have the sensor, you have auto heat.

The "whirring" sound you hear is the servo/actuator rod
in the auto heat controler which opens the butterfly valves on
the heat exchanger.

If your butterfly valves are not opening,
I suspect a broken actuator rod connector,
or seized butterfly valves.

Gerry

[Marlon Targa 86]

Ok, so:

1. butterfly valves don't close when I turn the heat on ( I can hear the servo running in the center console )

2. I don't get any current when I test voltage coming out of the cable plugged in the heater blower

What's next?

Marlon

[Scott R]

There is an arm that goes between the heat lever and the server inside the auto heat housing. On the end of the arm is a plastic socket that fits over a ball (just like the throttle linkage) If someone has pulled hard enough on the manual lever it will snap that ball and socket.

[Marlon Targa 86]

Originally Posted by Scott R

There is an arm that goes between the heat lever and the server inside the auto heat housing. On the end of the arm is a plastic socket that fits over a ball (just like the throttle linkage) If someone has pulled hard enough on the manual lever it will snap that ball and socket.

I have auto heat.

[Scott R]

Originally Posted by Marlon Targa 86

I have auto heat.

yes, but do you also have a single lever coming out of the auto-heat unit?

[Marlon Targa 86]

Originally Posted by Scott R

yes, but do you also have a single lever coming out of the auto-heat unit?

I do? I haven't seen it. It's a rotary switch and that's it. Am I missing a part?

[Marlon Targa 86]

Man, I made a typing error:

I DO get current when I test voltage coming out of the cable plugged in the heater blower

[Shadetree930]

Ok listen up.

If you have autoheat you must determine if the servo is actually attached to the rod that works the cables that close the dampers.

To do this you will have to remove the passenger seat and then pop the passenger side inspection door.

This is what you will be looking at inside the door.



Try the autoheat control knob to activate the servo.

Does the servo move? Yes? Good.

See the rod? It is still attached at the servo end?

Does the rod move? Yes? Good.

Now does the rod move the cable attachment at the other end?

My guess is that once you open this up and look you will find that one or the other ball clips has failed.

Replacement is a 1 or 2 buck over the counter part from your local Porsche dealer.

Pro-tip .... if you replace either ball, replace em both. Rod measurement should be 118mm center-of-ball to center-of-ball.

[86 911 Targa]

Originally Posted by Shadetree930

Ok listen up.

If you have autoheat you must determine if the servo is actually attached to the rod that works the cables that close the dampers.

To do this you will have to remove the passenger seat and then pop the passenger side inspection door.

This is what you will be looking at inside the door.



Try the autoheat control knob to activate the servo.

Does the servo move? Yes? Good.

See the rod? It is still attached at the servo end?

Does the rod move? Yes? Good.



Now does the rod move the cable attachment at the other end?

My guess is that once you open this up and look you will find that one or the other ball clips has failed.

Replacement is a 1 or 2 buck over the counter part from your local Porsche dealer.

Pro-tip .... if you replace either ball, replace em both. Rod measurement should be 118mm center-of-ball to center-of-ball.

The control rod connectors are visible with a penlight by removing the E-brake grommet.