I have a 93 aerostar.Front heat is barely warm.Flushed core.OK.I think blend door may have something holding it slightly open.How can I check this.I took heater cover off.When I open and close door it sounds like it is behind heater core.Any help is appreciated...Thanks...Jim

 

Do you have air coming out of the Defroster,vents and the floor vents ok? Or is it a heat problem?

 

I would check to make sure that the vacuum lines are still attached, They tend to "blow off" of the tree in the engine compartment. Take a look there first before tearing into the heating system.

 

everything is working ok.I have heard pencils and things can get stuck in damper door.I want to know where to get at damper door.I took off heater core cover and I still feel cold air coming in behind core when temp control **** is turned all the way up(or from blue to red).Is door right behind core?....Jim

 

I'm not sure with the 93 but I think the blend door is moved by a cable not a vaccum line. Will the temp **** move freely all the way from hot to cold and back. I had an ink pen fall down the defroster and block my door. It was a 91. Instead of a **** there was a slide control. It would not move all the way.

I removed the cover from the heater core like you. If I remember somewhere to the left or behind the core I could get to the door. I got the pen out and that fixed it.

Do you have rear heat? If so how is the heat in the back.?

Having a thermostat stick open can cause this too.

 

Rear heat is good.Just the front is not real hot.

 

First things first;
* Check coolant level, refill by the book if necessary. Instructions in owner's manual. If there's air in the system u loose heat.
* Check heater hoses for heat. The one going to upper intake is the inlet to heater core, the lower is the outlet. They should both become warm if coolant is present and circulating.
* Check rotating blend door function. Turn heat fully to red, blower to max. Check if there's air coming out of the proper outlets ; Def, Mix, Heat, Off, Vent a.s.o. If there's ANY air from VENT when there shouldn't be, your rotating blend door is stuck or damaged.
* Check vacuum hoses. Just if they're all attached...
* Check vacuum "motor" inside top of dash. Remove top of dash, fairly straight forward on pre-93. Check top of rot. blend door mecanism vac. motor on right side. Vac operated arm should turn small plastic rotating device on top of rot. blend door. Two positions; one for Heat-mix-def and one for Vent. ...Plastic details tend to break.

If this is the problem, (as often found), a fix will include some glueing and maybe new handmade details.
Access to bottom of rot. blend door is on the left side of heater core with the cover off.

I fixed mine making a new top attachment on the rot. blend door and it works fine.
Low coolant level still leads to cold inside air though...

Good luck

 

NorthernStar,

Some good ideas there. One correction though. The blend door only diverts air through or around the heater core. It doesn't effect the direction. If someting blocks the door from closing you get a mix of hot and cold air.

My 94 has a coolant bypass to keep the coolant from going through the core when not needed. LIke Max Cool and off. I don't think the 93 had this or I would have suggested looking at it.

There is a fresh air inlet that has a damper operated by a vacuum motor. Someone had a problem with his and blocked it closed to get more heat. Just an idea.