Heater

[91S10]

My truck wont blow hot air. i left it warm up for 10 mins, and still no hot air whats wrong.

[jsgold]

Several possibilities. Themostat stuck open, clogged heater core, or vacuum leak causing the heater door to stay closed. Could be any of these, including low coolant in radiator.

[hakogen]

what year is the truck and what kind of thermostat do you ahve?

i bought a failsafe from autozone, and it locked open on my '01. took me like a week to think to check the thermostat. lo and behold, it was just that.

[91S10]

Its a 91, and its just the stock thermostat so we it is idk.

[hakogen]

go to your local parts store and buy a plain jane thermostat and slap it in. the stat and gasket should cost less than 10 bucks and you can change it in about a half hour. this is where you should start.

[hakogen]

crap i forgot to mention:

if you ahve an actual temp guage in the dash, it should be up around 180. otherwise it might not be the stat. if its down aroun 100 - 120 its prob the thermostat

[dmbrisket 51]

ive got a vacume leak and not saying its the same for all vehicals, but my 98 has a vl and its stuck open, hot as hell in the summer time

[hakogen]

you need one of those busdriver type mini fans, brisket. hehehe.

[dmbrisket 51]

Originally Posted by hakogen

you need one of those busdriver type mini fans, brisket. hehehe.

lol, my girlfriends grandpa has the same exact truck, and one day we finaly said Fu*k this and put ball valves on the heater intake, let it flush through every now and again in the summer

[91S10]

My temp gauge is stuck at 100, it wont move from that. Probably next week ill pick up the thermostat and stuff, b/c i dont get paid till then and i dont drive it that much either so ill change it later. Thanks

[hakogen]

Originally Posted by 91S10

My temp gauge is stuck at 100, it wont move from that. Probably next week ill pick up the thermostat and stuff, b/c i dont get paid till then and i dont drive it that much either so ill change it later. Thanks

thats most definately the thermostat locked open. dont forget the gasket. good luck!

[sector95]

Originally Posted by 91S10

My truck wont blow hot air. i left it warm up for 10 mins, and still no hot air whats wrong.

Changing the t-stat for the engine *probably* won't fix your problem. I mean even if you have no thermostat, the coolant will eventually get hot and, unless you're driving around in sub-zero temps, there will be some heat coming out of the heater.

I have an '85 S10 and I had a '93 S10 and they both use vacuum motors to control valves (or doors) in the HVAC plenum under the dash; if this were my truck, that where I'd focus my attention. My guess is one of these vacuum motors has gone bad (has a leak) or one (or more) of the vacuum lines is leaking or fallen off. You don't say what year your truck is (a '91 maybe?). On the older style (pre '93) S-10's there is a main vacuum connection to the Heat/Vent/AC dash control panel; the panel has a multifunction valve that routes vacuum to the selected motors depending on what you've selected...that valve could be broken or leaking. The source of the vacuum is from the engine intake mainfold and you may have to do a little searching to find where it ties in.

Are there any other selctions/functions (defrost, vent, etc) that don't work?

Go ahead and change the t-stat, but I think you'll find it won't solve your problem....

...just my humble 2 cents.

Mike

[gijim19]

suggestion: If the thermostat doesn't help the problem, check the heater core. The easiest way to do this is to check the passenger compartment for water on the flooorboar. Also, when the core cracks anti-freeze is blown out the vents and fogs up your windows from the inside. If any of this shows, I suggest going to a shop and letting them struggle with it. It's a job and a half to change the core. These are just a couple of humble suggestions. Oh yeah. If you should see a leak at the fitting going into the block, go gentle on it. I broke the fitting off inside the block and had to take the whole intake manifold off to re-tap the hole. oops

[dmbrisket 51]

Originally Posted by gijim19

I broke the fitting off inside the block and had to take the whole intake manifold off to re-tap the hole. oops

gijm19, that must have really sucked, funny as hell from where im sitten, but that must have taken hours

[91S10]

Sometimes there is a big puddle in the passenger seat floor. i figured i had a leak somewhere, but i guess its that