Heater Problem

[calebhaney]

Hey, I'm new to the TDR, pretty excited about it. I own a 92 3/4 ton fairly stock 12v. Runs amazing. Anywho, heres the scenario, my a/c works amazingly, never stop unless i turn it off. However when i turn on my heater it blows for about 5 seconds, then slowly stops blowing completely, no hot no cold, nothin. Any advice on what this could be?Vacuum line was my first guess?. .

Thanks alot

Caleb

 

[Tippin Spotted Cow]

The stone age heater control system we have on these trucks sometimes makes for some interesting outcomes. If your brake booster seals are going... your climate controls will suffer. Does the fan stop blowing, or can you still hear it blowing, but the ducts close up? Judging by the fact that your a/c works fine, I would say you're right with the vacuum line thought. As you loose vacuum in your lines to the climate control, the ductwork control moves and shuts.



Also, I'd hate to point out the obvious, but when you put the heat on, it switches to blow out the bottom vents under the dash. These trucks don't switch the ductwork very fast, so for about 5 seconds it blows out the top vents while the vacuum is changing the routing, thus making it seem like the heat is shutting off. Turn it on "vent" and crank the temps up to the top to get hot air out the high vents.