Hey guys I was just driving my truck the other day when I turned the heater on it was cold like if I had the a/c on. I really dont know what it could be. Has this happend to anyone? If so what can it be? Thanks
-Ivan

 

Did you switch temperature control over to hot? I think one of of two things has happened to your truck. Your lightning is no different from any other F150 ive worked on. You could have a bad temperature contol switch or a bad blend door actuator. You could diagnose this by removing that big black cover under the center of the dash near the floor board. If im not mistaken the blend door actuator is a square box, cream in color. Look at the rod on the end and see if it moves when you turn the temperature switch from cold to hot.

Good luck.

 

mine does that **** too... ill check that tonight

 

I don't know if this would translate to an L or not. But I remember having the same problem a long time ago in my GT and it was due to low coolant level. Just an idea.

 

i had that problem once the thermostat was stuck open

 

YEP
Usual problem when blowing cold is
NO fluid in the system YIKES
But you must have checked that already ? RIGHT ?

Sounds like n20 has ran into this before, I'd check out what he said

 

just happened to my wife's SUV. thermostat stuck open. replaced and was ok.

Dave

 

could also be a vacuum leak keeping things from changing correctly under the dash .. The function selector is vacuum operated AFAIK

 

Hey guys a need problem is the when I put it on defroster, The window gets all fogged up so I am guessing it is going to be the damn heater core. I will let you guys know what happen. Thanks alot for the info
-Ivan