Brrrr - heater blower function in an 83 cab

[mhackney]

Now that my "no start" issue is solved (bad fuel pump) it's on to the next thing. I am on the road this week and the car was left outside overnight at a hotel in Elmira, NY. It was covered with thick frost and the air temp was 15 deg (F) when I started her up. No problems there. The "problem" was I froze my rear off the entire trip to Rochester this morning.

I now understand how the heater and fresh air controls work in the 83 Cabs. On the dash I have 1 lever on top to control fresh air intake and fan. Then the middle lever controls where that fresh air goes (defrost or cabin). Below that is a red lever that controls where the heated air goes (defrost or cabin). There are two levers (red) between the seats to to control heated air from the engine compartment. My AC has been deleted but the AC fan and controls pump air through the center dash vents only (and I have it turned off now).

So, here's my question... I don't know how much hot air is supposed to be blowing when:

the top lever is all the way to the left to close fresh air completely
the middle lever is midway - and shouldn't this be irrelevant if no fresh air is coming in (top lever left)?
the bottom red lever controls the hot air between defrost and cabin. For this post, let's say it is set to defrost only.

Now, with the red levers between the seats all the way up and the car warmed up, I do feel a little warm air coming out of the defrost vents and the side door vents when driving. Not sure about standing still, I forgot to check that. How much hot air does the rear blower push? What's the best way to test that the blower is working?

thanks,
Michael

[Autoban]

Michael:

I have an '86 Cab and I get my cabin nice and warm. I also deleted my AC but left the controls in the center console since I use the fresh air blower of the AC (located in the smugglers box) to blow air into the cabin. My car has foot well blowers on each side (not sure about yours).
I turn the top lever on the dash off and the middle lever doesn't matter for the heat. Unless I need to get the windshield defrosted I keep the bottom lever to warm the cabin (lower outlets). I noticed I get more total air into the cabin this way (my wife loves to take her shoes off and warm her feet this way). I turn the two center vents in the dash off since they will only deliver cold air, while the two outside vents will do hot or cold.
To get a good flow of air flowing (especially during city driving) the blower in the engine compartment has to run. The blower in the engine compartment has to run or the foot well blowers will not run. The blower in the engine compartment should come on when you turn on the ignition and you pull the red levers between the seats (you should be able to physically hear the fan run when you open the hood). I have a turn dial between the seats with 0 to 3 settings on them. This dial controls the speed of the foot well blowers.
When I first got my car the blower in the engine compartment was not working thus the foot well blowers did not work either. Nevertheless I was still getting quite a bit of warm air on the highway(I picked up my car in Michigan and drove it to Virginia in the beginning of January 2012). There is a relay on the left hand side in the engine compartment (under the cover) which controls the functions of the blowers. In my case the relay was not turning on the engine compartment blower. I opened the relay and cleaned the contacts. Since then all my blowers are working fine. There was a thread detailing the same relay, you should be able to find it if you search.

Hope this helps,

Juergen

[pmax]

Minimal heat at idle usually means your engine compartment blower is burnt out.

Test it with a 12V source.

[mhackney]

Thanks Juergan. I don't have foot well blowers. But I do suspect my engine compartment blower is not working.

To be clear, can I just turn the key to accessory (engine not started) and be able to hear/feel the engine compartment blower run when I raise the red handles? If so, I am pretty sure it isn't. If that's the case, I can check the relay and will search for the thread.

Thanks!

[mhackney]

Thanks pmax, I missed your post responding.

Sounds like I'm on the right track - that my blower is not running most likely. I should be able to figure it out. I have some jumpers with me so I can check it also.

[mhackney]

Found this post that pmax replied to with relay and micro switch diagnostics:
Heater blower - no relay?

I'll start there after work tonight.

[Autoban]

Michael, just realized that you have an SC. On my '86 the engine blower runs by just turning the ignition on without running the engine. I started by unplugging the blower and measured if any voltage got to it (in my case it didn't). Then I traced it back to the relay having input voltage, but no output voltage.

Good luck,

Juergen

[mhackney]

Thanks. I haven't been able to determine yet if the SC blower comes on with the ignition in accessory position. But I can do the other checks and start the car and measure the voltage. It would just be easier to hear if it is supposed to energize in accessory.

It's a pain that I can't find a good high resolution wiring diagram for this car. The plight of owning a 1 model year car!

[wrxnofx]

I have an '87 so mine might be different, but if I put the car in accessory and turn on the heat, the blower fires up.

If this method does not work for you, you can pull the connector off the blower and put a 9V battery on the motor terminals. If it doesn't spin, it's fried.

If it does spin, then check and see if you've got voltage on the harness connector end. If not, then I'd move on to the relay.

People are on here all the time selling their used blower motors. That's how I got mine 3 years ago.

Here are a couple (I don't know if the motor for the '87 is the same as for the '83):
Misc parts / 911 1983
FS: Heater Blower Engine Compartment

[mhackney]

It was way too cold and dark (I'm on the road not at home) to do any debugging. But I can say that there is no blower running from the engine bay when the key is turned to accessory and the between-seat levers pulled up. Stopped there is just a little hot air coming out of the defrost. The faster I go the more air comes out. Tomorrow is supposed to be a bit warmer here in Rochester so I hope to be able to do a little detective work. It would be nice driving home on Thursday a little warmer.

I do think this is a recent thing, I recall driving in the snow with the top down back in April and the heater on full blast belting it up from the cabin vents. So much so that I had to turn it down. I was always confused by the dash levers so I thought that I just didn't have them adjust properly. now I understand how they work and what they do thanks to some posts here.

[wwest]

My 88 has a header blower control module that contain a relay that is activated by the lever switch.

Of the 3 fuses in the engine compartment the top one supplies power to the control module, the one down powers the blower.

[mhackney]

Thanks. I have a plan of action now, I just need some light and a little warmer weather (or wait until I get home on Thursday).

[mhackney]

Ok, finally got time to test. The motor is bad - took it apart and the brushes are gone. I tested the circuit and everything works as it should - even the micro switch. And to answer my question, the heater blower does run with the car in accessory (and the heater levers pulled up). Time to find a new motor.

[sugarwood]

What year included the additional footwell blowers? My '86 has them.

[wwest]

I think there is a blower available with full depth blower wheel, improved CFM.

[mhackney]

A friend had a blower motor "laying around". It made a bit of noise so I popped it open and cleaned and lubed it and now it is quite and works great. Heat!