Blend door or heater core???

IrnBru · Oct 16, 2014

Is there a good way to tell which one is causing the lack of heat? I have an xlt with regular controls so things look mighty simple. I've watched the dash removal and glove box access videos on you tube but can't figure out which one is causing the issue. On 70* days I can switch to hot and get nothing but barely warm through the vents. Need help before the white stuff starts flying! :think:

Bedrck47 · Oct 16, 2014

check your heater hoses under the hood The two hoses should be about the same temps outlet may be slightly cooler than inlet.

See if you can see the blend door moving

IrnBru · Oct 16, 2014

OK, I'll check the hoses at lunch. Whats the best way to check the blend door without cutting holes?

Bedrck47 · Oct 16, 2014

can't give you a answer on that part Never had to check mine I'm sure someone will chime in and help

IMINYOURCHAIR · Oct 16, 2014

You can hear the airflow change and feel it flow less. The heater core doesn't pass as much air as the evaporator can.. Try turning the fan on hi and panel then go from cool all the way to hot quickly and listen and feel for a change in airflow. If you find you have a hot and cool heater hose you can try to back flush it but it will likely be too clogged to be effective at this point...

IrnBru · Oct 16, 2014

IMINYOURCHAIR said:
You can hear the airflow change and feel it flow less. The heater core doesn't pass as much air as the evaporator can.. Try turning the fan on hi and panel then go from cool all the way to hot quickly and listen and feel for a change in airflow. If you find you have a hot and cool heater hose you can try to back flush it but it will likely be too clogged to be effective at this point...

That did the trick. Flow of air definitely decreases when switched to hot. Guess my heater core is plugged. Any tips on clearing the clog?

IMINYOURCHAIR · Oct 16, 2014

get ready to just replace it... mine clogged when I bought the truck last november, I got it to flow but the heat wasn't good and it started leaking shortly after in july...

In the mean time, you will want to go get some 5/8 heater hose and some clamps, disconnect the core from the engine connections and hook up the heater hose you got, then you want to run hot water through it backwards.. some have soaked it in clr or something overnight but I don't recommend that

IrnBru · Oct 16, 2014

Okay, thanks for the help.

IMINYOURCHAIR · Oct 16, 2014

Here is some of what came out of mine at 280k.. much more than that came out when I ran more water through it, it was like mud/sand/rust

IrnBru · Oct 21, 2014

IMINYOURCHAIR said:
Here is some of what came out of mine at 280k.. much more than that came out when I ran more water through it, it was like mud/sand/rust

Went camping over the weekend and haven't had a chance to flush it yet. I suspect mine will look like that too.

Blend door or heater core???

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