I just got a new heater core installed in my 87 T2 and the heat decides when it wants to work. Today it worked for half of my drive home then started blowing cold air. Would it help to desolder and resolder the heater controls/logicon box? Please post all Ideas.

Thanks

 

maybe u have air in the system? did u bleed it?

 

sounds like the flap that moves inside may be acting up. Cycle through the buttons and listen to hear if it is moving.

 

air in the system would not cause something like that. Even if you had large air bubbles in the system, the only thing it would do is make the car run hotter, may throw the coolant signal too. (not sure)

 

I always thought that there were plugs in the heater coil ends to prevent debris from getting in there during shipping/handeling. Maybe you forgot to move them lol.

 

The system is bled and the buttons function properly.

 

The heat worked this morning and got weaker and weaker. This afternoon its back to no heat again..???

 

so basically it sounds like whenever you first start the heat up its good, then it fades away... let it sit a little bit, go back out and its hot again, then fades away? somethings obviously working then quitting. ide check the flapper door.

 

5 bucks on the air theory. I say you start the car, pop the hood and remove the rad cap let the car run awhile, allow themostat to open top up with rad fluid mix. let the car run 20 mins and keep topping up the rad fluid. Your problem could be that easy and it would cost you less then 5 bucks to fix just my to cents, i know its been said it was flushed. but they may not have flushed well.....

 

Where is the flapper door located? I will also try to let more air out of the system.