Prizm Heater Not Working - Blend Door?

[GeoPrizGirl]

I am running out of things to look at here, so I thought I would hopefully get more ideas on why my heater is not working very well.

My heater is slightly warm when the car is idling, but blows cool/cold air while driving and the faster I go the colder it gets. It's never hot, even on full blast. I replaced the heater core over the summer since it was leaking. Thermostat was replaced, car is running at normal temp (halfway mark), checked the heater valve, coolant is full, I doubt it has air in it anywhere. I can't think of what else to check EXCEPT the blend door, and I don't know how to check that. From what I could read up on it, it could be a problem.

Here is where I'm not sure if I messed anything up. When I was replacing the heater core, I completely removed the Evap core since it had the biggest mouse nest I've ever seen in it. The A/C didn't work as it was (it's got a leak somewhere) I decided not to spend the money for the new evap core. I don't use the A/C anyways, so I figured I wouldn't worry about putting the mouse-nest one back in. Now I'm not sure if this could have caused a problem with the blend door, or if maybe I messed up the blend door some how when replacing the heater core.

Frankly, I don't understand the HVAC system. I could just use a little insight. I understand how the heating system works (for the most part) I just don't understand how it relates to the A/C system.

Bottom line - Is it possible that removing the evap core caused this problem? If so, is there any way to fix this without actually fixing the A/C system or buying a new evap core? Does it seem like it could be the blend door? Is there any way to easily check the blend door? Or will I need to take the whole car apart again?

I tell you, that heater core sure was a PITA to get to and I don't want to do that again unless I have to!

Thanks in advance for the help!

[Bitter]

if you hold the engine at 2500rpm in park, what does your heater temperature do?

[GeoPrizGirl]

Haven't tried that. I'll try it this afternoon and see what it does.

I did try putting cardboard in front of the radiator to try to make it run hotter. Didn't affect it at all.

[Bitter]

I don't think its a blend door, it would be cold all the time because the flap would not move from cold to hot. sounds more like it could have air in it or the engine is cooling itself off. what temp thermostat did you put in? have you flushed the cooling system well? any gunk or debris?

[Zembonez]

Actually - It could easily be a stuck blend door. When stopped, less outside air is mixed with the heat - letting the heater work somewhat... but when moving, forced cold air would come through making it ineffective (and cold).

Get under the dash and see if you can see the blend door actuator. You may be able to at least manipulate it to the closed position so you have heat until you can get it fixed.

[GeoPrizGirl]

The cable that controls the Recirculation door had come unattached. Without the cable attached it was in the halfway open position. It was an easy fix, just put the cable back on it's hook and make sure it can't come off again!

Thanks for the help!

[Zembonez]

Great!