I have an 88 F150 and the heater is not blowing hot air. It is blowing warm enough for the 40 and 50’s we are at now, but will freeze me out if it gets any colder. I have checked the usual (blend door opens and closes fine, heater core’s not leaking and has been replaced last year, heater hoses are not switched at the core). The truck gets to operating temp fine, but the air temp feels like you have it in the middle of the range instead of all the way to the right on high heat. Any ideas would be greatly appreciated.

Thanks
Lonnie

 

Are both heater hoses hot and the (nearly) same temp?

 

Yes they are both hot.

 

Upper and lower radiator hose hot? What temp thermostat is in there?

 

Yes both are hot. If memory serves me, the thermostat is a 180.

 

Sounds like maybe the blend door control isn't reacting properly to the temperature setting of the temperature control. Have you turned the control all the way to max and if so does the blend door close completely eliminating any entry of outside air?

John

 

Blend door is fine. I pulled the panel off exposing the heater core and I can see it open and close fine. I even disconnected the cable and checked it. The dadgummed thing has me stumped. I guess I should be glad it's not the AC stuck on and blowing cold.

 

My truck runs best with a 195 thermostat. Nice heat too.

 

Heater Core Is Clogged I Just Changed My Dads Cuz It Was Doing The Same Thing. So I Changed It Now It Will Burn You Out

 

Hi, believe it or not I went through the whole dash on my 92 F150 before I found out the plastic control **** was stripped on the temp control. It felt fine, but after I actually had the heater control out of the dash, I found the metal core was just turning around the center of the ****. Always the last thing. Heater works fine now. Had the same indications, usually luke warm air blowing through. Good luck. ***** are 18.50 from ford per. I'm looking for used now.

 

Did you feel the core to see if it is hot?

 

fokkersauras,

You don't know how much time your post saved me! I was ready to go in for battle with the blend door and all the other stuff and then, per your advice, pulled off the ****. BINGO! The plastic was cracked! Thank you, thank you!!

Tom99

 

Well heres what happened to me and I'd never heard/seen of it. When i got my truck it had the dealer installation shoebox a/c system. So i went to the yard and got a factory system, refoamed the blend doors and installed a new heater core. But i didn't do a good job at visually instpecting the new unit. So for 5 years I had marginal heat. I live in Ga so it doesn't freeze your nuts off. Well one day I smelled coolant in the vent air so I knew this was a good chance to see what was going on down there and keeping it from blowing hot air. I had already checked my hoses which were both getting hot. I even swapped them just for kicks-no change. So I ripped into it one day and come to find out, if you held the old core up to the sun, you coulnd't see light!! Very little light at that. When they made the core, all the fins were crushed in the inside of the core. It basically looked like somone stuffed a bunch of steel wool in the fins...kinda something like that but you could tell it was a bum from the factory when they finned it. So I installed a new one after looking through it and I got hot as ***** heat now. Hot coolant was flowing through it but air couldn't go over it! For 5 years!! Sheez! So this could be your prob too unless it stopped up on the inside.

 

Also, remember, it's always a good thing to run your heater halfway through summer sometime, when you're on the freeway. It keeps everything in order, same with running your AC when it's the middle of winter and cold outside.
I've done that my entire life, and rarely have AC or heating issues.

 

Lonnie, I would also make sure I had a thermostat rated at 195 degrees for your truck. Any Fuel Injected vehicle with a o2 sensor, the engine will perform better all around.

This is what your Ford engine was designed to run at. In a flushed and clean cooling system, your engine will also deliver peak MPG with the correct thermostat. With the price of today's gasoline, this is important. With a lower stat, your engine is wasting and burning more gasoline at cold start-up and through the warm up cycle than you might realize. Unneedlessly.

180 stat 160 stat are mainly designed for old, worn carberutor engines where radiator plugging, or restrictions from lack of maintenence through the engine block passages might be an issue.

Good luck!

Ed