Heat/Heater not working?

[creosote7]

I have a 98 Suburban that doesn't seem to put any heat out of the vents. When I turn the thermostat to the red section and turn up the fan all I get is normal air with a little burst of heat every now and then.
Worked fine last year and now that the cold weather is coming this is the first we tried it this year.
The engine is completely warmed up and everything else seems normal.
I called a the service dept at the GMC in town and all they said was bring it in for us to look at.

Any ideas what would cause this? If there is a easy fix I would much rather do it myself before the dealer looks at it.


thanks,

Wayne

[2000CAYukon]

Usually, this can be one of two things.

1) The heater core is clogged.
2) The actuator is not working (or not getting vacuum). The actuator controls the amount of air from the heater or a/c.

First thing is to check the temp of the heater hoses going to the heater core. With the engine warmed up, both hoses should feel about the same temp. If one hose is hot and the other is much cooler, than the heater core is clogged and should be back flushed.

If both hoses are the same temp, then you need to look at the actuator and it's vacuum source.

//2000CAYukon

[kevin_msu]

I'm having the EXACT same problem with my 97


heater is going in and out, i turn the fan off, then turn it back on and the heat comes back for like 30 seconds, then goes out again

then this just happened:

i look down and notice that the 'check gauges' light is on

then i notice the engine is at 250 friggin' degrees!

'holy bleep' and i turn the heat all the way up, it starts working and boom, the needle drops all the way back to 180 in about ten seconds.

this sucks.

[kevin_msu]

PS:
got any pictures so i know what to look at?
its like 5 degrees out here in michigan and by the time you open the hood you can't feel your fingers anymore

[creosote7]

Well...I feel stupid even mentioning the solution to my problem.

The whole issue turned out to be my radiator coolant was low and the reserve tank was empty. As soon as I filled them up the problem disappeared. I'm sure that will be the answer to your issues as well.

Good luck

[kevin_msu]

^ oddly enough, i just checked it today.

i didn't think i would have too cuz i got a "full service" fluid and oil change.



M'n F'er was EMPTY. FRIGGIN EMPTY.

SOB took half a thingie of dex cool.

i think they drained it and forgot too replace it.

good thing its been like 15 out here with a wind chill of -5

[hitman98]

Originally Posted by kevin_msu

^ oddly enough, i just checked it today.

i didn't think i would have too cuz i got a "full service" fluid and oil change.



M'n F'er was EMPTY. FRIGGIN EMPTY.

SOB took half a thingie of dex cool.

i think they drained it and forgot too replace it.

good thing its been like 15 out here with a wind chill of -5

Buy a new heater control assembly at an auto wrecker, mine did the same thing, I unplugged the old controler from the dash, threw in the new one and wow heat gallore.