Just changed my heater core in 86 mustang.Got lucky and did it through the glove compartment.Problem is it didnt make any improvement much over the old one that took forever (15 min for a little heat)Blower fan does work though.
Im getting air through my vents but very little

So maybe my old core was ok after all.
I know it takes about 15 minutes for temperature gauge to reach halfway so
could it be my thermostat that is the problem or if it was my thermostat would temperature go up at all.
What about a heat control valve or is there one.
Thanks as Usual.

 

did you check your vacuum lines in the engine bay? There is a plastic line along the firewall that controls the vents. If that is broken or has a hole in it, your vents won't work or just blow very little air.

 

Does anyone have a picture of which one that is on a 86 mustang gt?

 

Is the car reaching operating temp? Are both heater hoses getting hot? Are all the vents working correctly when switched? It might just be a t-stat problem.

 

It takes about 15 minutes and then the temperature reaches the halfway point. Seems to take a little long.I will check and make sure both heater hoses are getting hot.I can feel heater core gets hot for sure and fan motor is blowing but im getting no hot air through vents.My blend door works but the foam around it is not that great.
On the diagram which is the vacume line in the engine bay that could be broken.The one that says from manifold that goes into check valve.Is that check valve the same as a heat control valve.
Sorry about all the question but my chilton manual doesnt explain CHIT!