Heater doesn't work

[whyte noize]

When I turn the fan on, nothing happens. I noticed that when I turn fan to high+hot+defrost, there is a little heat that comes out the vent on the dash and eventually defrosts the windshield. What should I look into? It'd be nice to have heat during these 25* mornings.
Posted via telepathic device

[JRANGER]

I am subscribed!!! I need info too as my defrost doesnt work and some vents dont work...Hope everyone can help ya

[motornut]

25 dam i'd break out the suntan lotion lol
try -25 lol........
check here

[JRANGER]

that under the dash?

[Corts60]

What year truck? Sounds like your fan is not kicking on. Did you check fuses?

[motornut]

Originally Posted by JRANGER

that under the dash?

yup behind the glove box

[whyte noize]

Originally Posted by motornut

25 dam i'd break out the suntan lotion lol
try -25 lol........
check here

Thanks for the pics. I'll check out those spots.

Originally Posted by Corts60

What year truck? Sounds like your fan is not kicking on. Did you check fuses?

Its an '86. I'll check fuses!

[JRANGER]

So another questions...How do i get the dash off??? The nuts above the glove box seem so embedded that i cant get a socket on them.....Im thinking about trying needle nose but dunno if ill be able to get a grip

[whyte noize]

Fuses are fine. The gadget near the gas pedal is intact.

Originally Posted by JRANGER

So another questions...How do i get the dash off??? The nuts above the glove box seem so embedded that i cant get a socket on them.....Im thinking about trying needle nose but dunno if ill be able to get a grip

That's funny. I was about to ask the same thing. I don't wanna go pulling things apart and not be able to put em back together.

[JRANGER]

Glad im not alone on that....You would think they could of used a phillips head like the rest of it in the dash bezel

[JRANGER]

tried needle nose and no luck

[whyte noize]

It's gettin dark out so I'm gonna save this project for later. BTW I have phillips screws that hold the dash on. There are phillips right above the glove box. Maybe my sh!t's rigged from the last owner

[JRANGER]

aww thats BS! lucky...Chevy or GMC?

[motornut]

don't need the pad off
screws under the glove door to remove it(arrows under door edge)
flap door behind it

[JRANGER]

i still need it off to restore it and my glove box is off...matter of fact i have to figure out how to put it on...I think its missing some pieces

[motornut]

as far as fan speed the resistor might be broken inside (arrows)

[motornut]

Originally Posted by whyte noize

It's gettin dark out so I'm gonna save this project for later. BTW I have phillips screws that hold the dash on. There are phillips right above the glove box. Maybe my sh!t's rigged from the last owner

try 7mm or like 9/32?

[JRANGER]

9/32 does the trick...rippped the 1 tube off for the heater though damnit...

[wilkin250r]

Like Motornut alluded to, I would check to see if the problem is the fan, or power getting to the fan. The first think I would check is the resistor pack that is built into the housing, it's the item that actually controls the fan speed. Your fan speed switch routes power to a set of coiled wires that add resistance to the circuit before going to the fan, and that controls the fan speed. If one or more of those coils are broken, your fan never gets power.

A simple multimeter will help significantly. Also, by analyzing the wiring, you could probably easily determine which connection is power to the fan, and which is ground. At that point, you could run a jumper wire directly to the battery to test the fan.

[whyte noize]

Originally Posted by JRANGER

aww thats BS! lucky...Chevy or GMC?

Do you want the short or long answer? It's a GMC. But the previous owner (2 owners prior) built the truck as a NAS Truck remake so it has Chevy tags. I think it was red with blue and yellow vinyl at the bottom, wrapping around to the rear bumper. The guy I bought it from removed the vinyl (most of it ) and painted it white. I'll post pics after I clean her up a bit and try to fix this heater issue.

[Ken 45LC]

Where does that actuator get its vacuum from? Or should i ask where does it attach to out by the motor? There are all kinds of vacuum lines unhooked by PO, and I'm not sure where they all go now. It's the wrong time of year not to have a heater, or be able to change from defrost to floor heat.

Thanks for the help,
Ken

[donut]

I'm currently trying to sort mine out also.
Non-AC trucks may not have the actuators, I believe heat only are cable operated. (please correct me if I'm wrong)

Vacuum lines go from intake to a "t", one side going to a vacuum ball, second going to a port between the dizzy and the AC box on the firewall. From there to the maze that is vacuum city under the dash.

Kinda off topic, but sorta related. There's an vacuum actuator in the cowl (vacuum comes from inside the cab) any ideas?
I do have the one next to the gas and one on the vent.

[Don SC]

Whyte noize, you said the fuse is good. did you check for voltage at the fan motor? You should get at least 10 volts dc. If you do, run another ground wire to a good ground and see if the motor runs with the new ground. If the fan motor still doesn't run, it needs replaced.

[Ken 45LC]

Donut, I believe you are correct that the heat only units only have cables. At least in my experience i've run across units with two or three cable hookups. But this is my first A/C equipped cab, and I'm not sure this mess is worth it. The PO installed an aluminum intake and a different carb, so needless to say, all the hookups for the vacuum are a little different. I did find the small vacuum line going in, but i didn't have time to check it for vacuum tonight.

Motornut, thank you very much for the photos, they are extremely helpful. When you change settings (from defrost to bi-level an so on) shouldn't you hear a small pssst of air noise? Or is my memory wrong again?

Thanks for the help,
Ken

[donut]

Both of my recent trucks had a vacuum "tree" in the intake (even the one I put an alum intake on) it ran the trans modulator (on the old truck) and current has dash vac, modulator, and I think my dizzy vac is there now.

"tree" would be just behind the carb, in your case, it may be just a pipe plug.