fdoyen

Replaced the heater core, now the heat works great. Problem is that the heat is now always on, even when I select A/C. I can't hear the blend door actuating, as I did before. The temp **** has no effect on heat temp.

When replacing the core, the blend door was hard open, and I couldn't move it. I was able to pull it out, straight up. I replaced it when I had the core in place.

Should I have been able to manually move the blend door? Any ideas on what my problem is? Do I have to remove the dash again to fix this problem?

mbb

In college I installed a 1/2" valve from hardware store in heater core hose for similar problem. Closed in warm weather.

yeah, PITA but price and time spent was right at time.

Never fixed it....traded vehicle in when got job.

I remember my dad putting cardboard in front of his radiator in the winter to increase the heater air temp in his old truck

Aahh. The good old days.

fdoyen

I'm in Texas, mbb, and have to have A/C in summer. With the blend door not moving, I don't have A/C, AND it's still pumping heat to the cab.

Why won't the blend move?

mbb

Im only familiar with EATC, if you have a **** I font know.

On EATC vacuum loss due to old. Oring causes it.

So does the very common broken blend door, or actuator.

Theres a fix for broken door, where you take out glove box and cut hole in evap core case to replace door. You can search for it. Avoids taking dash apart.

white89gt

Best thing to do is remove the actuator and see if it is working. If it is, you're going to have to pull it all apart. If it doesn't move, you have missed plugging something in somewhere.

fdoyen

Bought a new F250, but still driving the F150 to work. It's been a great truck, except for the heater core, so I'll be keeping it. Thanks for the advice. If the weather's nice during Christmas vacation, I'll work it then. I WILL fix it before May.

white89gt

FYI - Dorman does sell a kit that you can cut into the box from behind the glove box. It runs about 30 dollars. The part number is Dorman 902-220 . It saves a lot of time, if you don't mind hacking up your heater box, etc. Of course, this is IF you find that something got damaged with the new door you put in.

Here's a video of an install of one.

Hexxus

I cant say what your problem is though I just did a heater core on a 2001 and the door wasn't moving back and forth manually and indeed was difficult to remove.