'89 Sub Winter Issue/Firewall

[Chantz]

Alright, so my 1989 Chevy Suburban is driving great, but my defroster seems like it's lost pressure. Now, we've gotten a lot of snow recently, and whenever we get a fresh dump of the stuff I get snow blowing out the defroster onto the dash. Could it be that it's plugged with snow?

As well, I'm trying to run 4-Gauge wiring to the back of the truck from the engine compartment, and to do that I need to go through the firewall. Does anyone know of a particularily easy way to do this? Because it seems that there's another layer besides the firewall getting in my way every other place.

[idmetro]

Chantz;

On my 86 the air for the heater/defroster pulls from the louvered area at the base of the windshield. When it's full of snow I can also blow some into the cab but as the truck warms up that goes away. I'd suggest clearing that area out as best as you can to lessen the problem.

I don't know if the defrost deflector in your heater case is vacuum actuated (mine is) but you might check to make sure you don't have a leak in the vacuum hose to the actuator and/or if your's is cable actuated make sure the cable housing hasn't come loose from the clamp.

In addition there is a foam gasket between the heater housing and the duct that goes to the defrost vent. Yours might have degraded or fallen out.

As for running the wire to the back of the truck; why not run it inside the frame rail until you get to the back of the truck and then bring it through the floor? You'll probably have to drill a hole to do so but you could position it under the seat out of harms way.

[Old Dave]

Chantz:

Which ever way you run the wire (inside the vehicle or along the frame rail) MAKE SURE YOU PUT AN INLINE FUSE OR THERMAL BREAKER SOMEWHERE IN THE ENGINE COMPARTMENT AS CLOSE AS POSSIBLE TO THE +12V SOURCE. Any short anywhere on this wire will will pop the fuse or trip the breaker and not cause a fire. Wherever you run the wire through sheet metal, install a rubber grommet and run the wire through the grommet to keep from chaffing the wire and eliminating problems down the road.

[Chantz]

Originally Posted by idmetro

Chantz;

On my 86 the air for the heater/defroster pulls from the louvered area at the base of the windshield. When it's full of snow I can also blow some into the cab but as the truck warms up that goes away. I'd suggest clearing that area out as best as you can to lessen the problem.

I don't know if the defrost deflector in your heater case is vacuum actuated (mine is) but you might check to make sure you don't have a leak in the vacuum hose to the actuator and/or if your's is cable actuated make sure the cable housing hasn't come loose from the clamp.

In addition there is a foam gasket between the heater housing and the duct that goes to the defrost vent. Yours might have degraded or fallen out.

As for running the wire to the back of the truck; why not run it inside the frame rail until you get to the back of the truck and then bring it through the floor? You'll probably have to drill a hole to do so but you could position it under the seat out of harms way.

That's what I thought was the problem, but I wasn't really sure. And when the heater is on, there seems to be a vacuum leak somewhere, so I guess I'll just have to follow it and find out where the leak is.

As for running the cord along the rail, that might be a good idea. That dash just has too much stuff in it to attempt drilling.

Originally Posted by Old Dave

Chantz:

Which ever way you run the wire (inside the vehicle or along the frame rail) MAKE SURE YOU PUT AN INLINE FUSE OR THERMAL BREAKER SOMEWHERE IN THE ENGINE COMPARTMENT AS CLOSE AS POSSIBLE TO THE +12V SOURCE. Any short anywhere on this wire will will pop the fuse or trip the breaker and not cause a fire. Wherever you run the wire through sheet metal, install a rubber grommet and run the wire through the grommet to keep from chaffing the wire and eliminating problems down the road.

I actually work at the place where I bought the stereo, and they hooked me up with a fuse holder and some fuses, and I've been warned about the gromets already, but thanks anyway for the tip