89 blazer heater not working

[overcool]

On my 89 blazer the heater wont heat.I have flushed out the system and is not plugged anywhere,but still won't Heat.The heater hose will not get hot.

[wolfox]

Possibly a stuck open thermostat? Does the engine temp rise any at all, or does it have to be run hot and hard down the highway before the temp gage rises the slightest?

[overcool]

Originally Posted by wolfox

Possibly a stuck open thermostat? Does the engine temp rise any at all, or does it have to be run hot and hard down the highway before the temp gage rises the slightest?

I just got the blazer.I checked for themostat and it did have one.I put one it put it got a little to hot and scared me so i took i back out.

[WVPurpleJimmygirl]

I have a 1996 gmc jimmy, NO heat as well

The thermostat has been changed, whole system blown out by air and heat still is bad. Cold air is blowing out, but pressure of air is slow. There is not too much different between med and hi. Got any other suggestions? I really don't want to replace heater core..... temp runs up and down normally. Heat still not working. GOOD LUCK

[wolfox]

*Holds head* I am getting a headache already, not a good sign.

What's the temperature of the thermostat you put back in, Overcool? Stock t-stat on these trucks is 190 Degrees F., not 160, 180...whathaveyou. If you are certain that you have no heater core, radiator or block obstructions, putting back in your normal 190 degree 'stat is going to be the best thing for you.

Since you *just* got the truck, have you done all of the upkeep needed to keep it fully tuned up and happy? This would include a radtiator/cooling system flush given it's age. Make sure all of the scale and crud is out of the system, and do not forget to reverse flush & forward flush your heater core.

Refill with 50/50 mix of coolant to distilled water when done and "burp" the cooling system free of any air. There are extensive topics that cover your specific problem if you'll use the forum search feature to locate them. Of note, there was a recent FAQ-like posting that covered general cooling system maintenance.

EDIT: Take note that there is mention of using a "leave-in" for a few days cooling system cleaner. Not a flush or acid flush. System cleaner is left in for about a week, it's cleaning is done by the mechanical motion of fluid and engine heat. Thoroughly flushing the system out afterwards until all fluids are coming out clear is a great step to getting back heater performance. I did this last winter, and it went from luke-warm at best to blazing hot, sauna-like performance. All of the flushing/reverse flushing in the world is not going to get scale and rust out of a neglected cooling system.

[WVPurpleJimmygirl]

temp is at highest 160.

[wolfox]

Originally Posted by WVPurpleJimmygirl

temp is at highest 160.

Your thermostat's most likely stuck open, it will need to be replaced with an OEM, 190 degree 'stat.

[Cailen]

Originally Posted by overcool

I just got the blazer.I checked for themostat and it did have one.I put one it put it got a little to hot and scared me so i took i back out.

This could be because you picked up a faulty Tstat (which seems to be common) or, like me, you had a SHITLOAD of air in the system. When I replaced my Tstat the temp came close to red line before I shut it off. After I let it cool down I burped the rad, filled er up, took her for a drive and she worked great.