Hi. I have a major or maybe minor problem. I have changed the actuator doir, checked heater core and still have a problem. I have heat for about 1 minute then it turns really cold. I can not find any help on this. It is a 1999 F150. It has vacuum lines and is nondigital. We have tried everything. At first it would only give a little heat on defrost then it finally gives some heat on the face. But it ONLY gives heat for about 1 minute then nothing but cold. I can cut it off wait a while then i have heat again but only for a minute. Help please. ANY ideas?????

 

What t-stat is in there? These trucks need a 190* motorcraft t-stat. Does the truck get up to operating temp? Once it reaches operating temp are both hoses coming frome the passenger side firewall hot?

 

User has two identical threads going. Post here instead, -

https://www.f150forum.com/f6/heater-...s-help-330590/

 

Ahhh gotcha

 

Yea, figured I'd try to fix that before anyone else fell prey lol.

 

Lol I hate being the prey

 

First off, check BOTH heater hoses when you have heat and when you don't. An infared thermo is a good tool for this. Start from the heat source and work your way into the air box. SIMPLE things first! There may of may not be a restricting orifice in one of the hoses. The hose will have a solid hard spot in it, this is where the orifice is located. Also, you say you've checked your heater core. The water running through the core needs to be constant. If its restricted, either at the orifice or at the core, the temp will dissipate quickly and since the flow is restricted, it will not return. I would suggest disconnecting both hoses and check for restriction and back flush the core in the opposite direction. Put long hoses on so you can witness that the flow is sufficient and what else may being coming out, like rusty blockage crap. Let me know how you make out. Hope this helps!

 

Jeezzzz....

 

Well somebody doesn't lol.

Some good deeds are out of reach for some...doesn't matter how easy you make it I guess.

 

Whelp you gave it your best shot. Lol