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Discussion Starter #1
I need to flush my heater core the in/ out lines. I have not done this before and I'm not positive on how to do it. Can anyone tell me how and post pix of the lines on the firewall? I just learned that since I bought my TB last summer there was no air filters inside. It was nasty to clean out. So that makes me think flushing the in/ out lines will increase flow of air. ? Help please
 

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Number 1.... there is no air inside that heater core passageways.
Number 2.... who told you you need to flush the core to remove bad odors? You can't
Number 3.... GM heater cores flush themselves out every time you start the engine, then they are either modulated, redirected or left wide open according to the HVAC system settings.

What you MIGHT be smelling is leaking coolant inside the plenum or sound deadened under the eash creating a funky order.

Is your carpet on the floor .... under the floor mats.... dribbling down the slanted floor? Puddles in the carpet or pad get really nasty smelling.

THEN there's always the possibility of condensate from the evaporator that's not draining correctly.
 

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Discussion Starter #3
No dead anything. I detail cars so it's very clean.

The in and out to the heater core I just flushed. Used a clean clear hose on the in and straight water hose on the out. Reverse flush! Heat is blowing like new now!
 

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Good on ya for fixing it.

I don't understand how cleaning out the heater cooling lines makes it any better - but you say it did so it must be so....

Cleaning the fins, OTOH -- different story.
 

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2004 chevy trailblazer_ls
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I think she meant she wasn't getting enough heat, reverse flushing the core fixed it for her. Must have been a pain in ass job.
 

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Syntax is important... and the written word tends to eliminate questions as to the statements being correct or not.

Then there's the possibility of sounding snarky when one asks if English is their primary tongue, and I didn't want to call the OP out for bad technical terminology.

Ah well... they are happy now.... that's what counts.
 

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2003 gmc envoy_sle
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I know it's outside the model year intended for the forum, but on my former '01 S-10 Blazer the heater core would plug up easily. The easiest way to determine the flow of the coolant is to cold start the car. Keep alternating feeling the heater hoses, where the go through the firewall. The one that warms up first, that's the one going in. The one that stays cool is the out one. On mine, the hoses were the same length. If I was away from home, I just switched the lines and back flushed the core somewhat as I drove. Heater cores have no moving parts. Coolant can flow in either direction.
 

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Discussion Starter #9
Yes I agree. I just attached two hoses and did the reverse flush. I wanted to see how bad it was. I bought my 02 Trailblazer and when I checked the cabin filters, I found there wasn't any there. It takes 2 that snug side by side. Same part number as the 2000 Silverado. It was not a hard job to reverse flush, just took me longer since I'm so short lol.
 
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