2001 S-10 Blazer Heater not working - Blazer Forum - Chevy Blazer Forums

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Old 12-12-2010, 12:57 PM
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Default 2001 S-10 Blazer Heater not working

Hi experts,

I am having an issue with my 2001 Blazer (s10 type) heater not working. It blows frigid cold air. Almost as if the air-conditioner was running. Now before I ask my question, let me tell you that I have done my dilegence on these GREAT forums and have found several VERY HELPFUL links to try different things. The thread for showing how to flush the heater core was awesome. I also saw the thread showing how to change out the belnd door actuator, another awesome link...both links were VERY WELL written and easy to understand.

1. Turn dial to heat (it's an manual system according to this forum - no temperature numbers, only red and blue color), I can hear the system act like it kicks over to heat (i think it is the air damper switching over - dunno really)

2. Turn blower all the way on in ANY position it only blows ice cold air no matter which position the directional vent switch is in.

3. When I set the directional vent switch to blow the air out of my dash vents, the air recirculator light stays on, depicting it is recirculating the air. However, in any other position, including the defrost it will only blink and go off. The Valvoline guy said that was not right....dunno...I am suspecting you guys know better and have a better answer for me on this. The Valvoline guy also said that when I turned it to heat the Air-Conditioner clutch was not engaged nor did it engage.

4.Temperature gauge warms up after engine runs a bit and stays right at 195-210 degrees.

5. According to "flush hearter core" thread on here, the pictures show that the inlet hose is the hose closest to the engine and the outlet is the hose closest to the fender well. SO with that said, after the truck has been running for at least 45 minutes, the outlet hose is VERY VERY hot, the inlet hose is warm...but not so hot that I cant hold it.

Side notes -
*Truck NEVER has overheated at all. Even during the hot summer months, it maintained between 195/210 temperature.
* Only blows ice cold air.
* I thought flushing the system would unplug my heater core. No luck, still blows cold.

What I have done to this point...
Took my blazer to Valvoline instant oil change and had them do a complete radiator flush. They technician said I had the green anitfreeze in there and this was a huge no no...so he replaced the entire system with DexTrol 50/50. He said he flushed with about 30 quarts of dextrol and got A LOT of sludge out. However, still no heat.

So here are my question(s).

a. Would the Radiator flush also flush the heater core, or do you experts recommend i still take my heater core hoses off and flush with a garden hose?
b. Could this be an electrical issue of some sort? Dunno what Im asking here really...just thinking that there may be some fuse out or something.
c. Is there a way to manually force the blend door to blow heat without using the actuator, and if so, anyone got a link to a thread on here to do it?
d. Any other ideas, suggestions, and tricks the experts can point me to would be greatly appreciated.

Thanks in advance all and I hope everyone has a Happy Holiday!

- Zed
Old 12-12-2010, 04:32 PM
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The way you describe the temps of the heater hoses, it sounds like the core is plugged. Try flushing it again with a bit of a stronger current.
Old 12-12-2010, 07:48 PM
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I believe that recirc only works when the dash outlets are selected.

I would recommend a heater core flush specifically if you are going to do it. Flushing the radiator cannot really assure that you will flush the core.

If flushing the core doesn't bring back the heat, then I would recommend that you remove the blend door actuator and manually manipulate the door to see if that works.
Old 01-17-2011, 08:46 PM
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I recently had ice build up in mine. To manually move the door, simply remove the actuator and turn the "top" by hand. It should move about 90 degres. You should be able to hear the blend door seal when turning. It will be easier with the blower off. With the blower on, the moving air will pull the door open/close. If the door is functioning correctly, it will "slam" shut both directions. hope this helps.
Old 01-18-2011, 10:43 AM
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From my understanding from some very reputable Mech's (friends) if you run the dex cool (orange) for too long even though it is "extended life" it turns acidic eating your gaskets. And if the green and orange mix it becomes jello like after a bit.

Try reverse flushing just the heater core. Remove the hoses and connect a 3/4 garden hose to the upper and check the flow and if need be work it back and forth i'll bet you get some nastiness that comes out. Most important watch you heater guage for fluctuations because that'll be you first indicature of a real (replacing gaskets/engine) type of problem.

I melted a piston in my last motor because of it!

Old 01-18-2011, 11:18 AM
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does water flow out of the core when you flush it?

ive heard of people using CLR or other harsh chemicals, and or compressed air. dont know if a weak core will hold up to it though, might not bother it at all who knows.

heres a good video.

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