New heater core...now no heat
 

The heater core exploded while my truck was in getting a new transmission. The shop told they would replace it free of charge while I was getting a new tranny installed. Living in So Cal it does not get used very often so I finally tried the heater this morning on my way n to work and I had it on high and I did not feel any warmth. Any ideas?

Re: New heater core...now no heat
 

Maybe they hooked up the hoses backwards?

Re: New heater core...now no heat
 

Wouldnt that damage the vehicle?

Re: New heater core...now no heat
 

Might have a bubble in the cooling system? I'd pop the cap off the radiator while it was cold and run it for a while until all the bubbles (if any) come out and then fill as necessary... Just a cheap way to rule things out.

Re: New heater core...now no heat
 

I'll give it a shot

Re: New heater core...now no heat
 

They busted your flapper door and didn't fix it.

Re: New heater core...now no heat
 

The most common causes are water level low and bad valve.

Re: New heater core...now no heat
 

Bleed the heater hoses. Its kind of like bleeding the air out of brakes. Its been an awful long time since I bled a heater, but as I remember it you crack the top hose loose while its running and let it flow until there's a steady stream of water.

Re: New heater core...now no heat
 

open your glovebox and look on top of the heater housing you can see the steel cable going to it make sure its not jumped off or work it back and forth the cable to see if its opening up and closeing correctly pretty simple way to check it

Re: New heater core...now no heat
 

And if you don't have water flowing through the loose hose, there's no doubt you have a bad heater control valve.

Also, too low a thermostat will effect heater output. like a 160, or a 180 or none at all.