I just replaced the heater core. The air blows out good, but it's only warm, not hot. Lastnight coming back from Raleigh, the temp was in the mid-30's and the water temp seemed lower than normal. Running 70-80 for an hour should get it fairly heated up shouldn't it? I was thinking maybe the thermostat was stuck open, but would that keep the water cool enough to not give me heat inside? How do I check to see if the heater core is clogged? What are the odds of it being clogged after only having been installed three weeks ago? I was reaing in another forum, and the truck guys were discussing a "heater box" and a "blender door". Is that relevant to the aerostar? If so, where are they and how do I check them?

 

some quick things to check. if the two heater hoses stay warm , not hot, then i'd think the thermostat is stuck open. and yes, that will cause warm not hot air in the van. if one hose is hot!! and the other cold, then i would suspect a clogged core. the blend door is a common site for air temp mixture problems, but it is in the dash. it can be checked and adjusted, but i would rule out the thermostat first.
you can search the forum under "blend door" or heater issues. i checked mine by taking the cover off the heater core and the glove box out. then reached behind the heater core and flipped the lever cold to hot a bunch of thime. i have found ink pens and crayons in there, lost by my darling children. if you just did the core, you probably know how to get to it. chances of a clogged new core are slim i would say, unles it get fouled on install!! cold in raliegh? good luck rick

 

It's good to hear somebody say the chances of the core being clogged are slim. That was a nightmare! I don't know why Ford invented those "quick-disconnect" fittings. I'll check the thermostat first then.

Temp in Raleigh was in the mid 30's this weekend. Here in Charleston, we're at 51 currently.

 

Check to see if your heater control **** is adjusted correctly. Ive gone 3 winters without a mechanic being able to figure this one out. Haynes has a nice picture on how to adjust correctly if you have access to a manual. You can get to these cables by removing the screws on the top of the dash...

 

How would I know if it's adjusted correctly? Is that in the manuel? I have a Haynes, I'll check into it, thanks.

 

I would try to put all the way to the top and it would feel like it was binding before it reached the top. There also was wear on the controller itself like it wasnt working correctly. (mine also wouldnt get hot)