This looks to be a problem with most of these trucks. I've read and read and read and tested and I'm still stuck with no heat. My front seat looks like Donald Duck lost his temper. I have to tell you, I'm pretty close....Heat has been working great till this year. I started hearing a flutter like a leaf in the air system. Next thing I know, no heat. AC will run you out cold.

No blown fuses or relays
No vac leaks
Heater core and system professionally flushed 2xs
No leaks from the core or fogged windows
Did the quickie and cut the air box....new actuator and blend door
Tested controls
Top heater hose is Hot, lower hose is hot, maybe not as hot though
Radiator hose is warm
Temp gauge is mid way and stays consistently
Not overheating or running cold even for the blistering hot summer we had and no issues with cold weather.....outside of no freaking heat

Only thing that has not been done is a thermostat and water pump. Water pump seems to be working fine.

HELP!!!

2001 F150 Screw lariat
4x4
5.4
150k miles

 

Something new....

I felt like the I have reached a dead end with the actuator and all the other potential problem areas, so I started to reassemble everything. For the heck of it, I took the radiator cap off to take a look at the level and start the truck. I was taking the lid off (before starting) and didn't think it was going to come off. When if finally broke free it sounded like I was opening an air ,lock on the space station. I let the truck run and about 15 minutes later I went to finish the assembly. To my surprise I am now getting warm air. Not hot by any means but noticeably warm. It's the same temp through all functions on the climate dial. AC still works great. I checked the water level in the reservoir and there has been no level change. Am I looking at a bad thermostat?

 

To start with, you need a new cap.

 

Well, put the new cap on and put in the new thermostat. Went ahead and buttoned up the air box and put all the actuator crap back together. Before I did, I did reach in and put my hand on the heater core and that thing was hot! The blend door does shut tight in both the AC and heat mode.

Now....I only replaced the coolant with plain water to take the variable of too much antifreeze out of the loop. Well, the temp gauge is going up and now sits just below half way. I have luke warm heat. Better than it was but still not like what I used to get as hot air.

So now what?

 

If the heater core is HOT but the heat isn't, you have a blend door issue or something else in the control system.

 

I cut the dash to examine the blend door. The control switch activates the door as it should for both AC and heat. The door has a nice tight seal and actuator holds it in place. No stripped gears in the actuator. I bought a new one just in case and put it in with the same results.

I was told that it is possible for there to be a clog in the heater hose and both of them be hot? Not sure about that. Like I said, I had the dash open to see the blend door and felt of the core while I was in there. It was pretty warm.

What else could be checked?

 

Well, I just got a call from my grandfather and he thinks he has it figured out. He suggested that it could be a large air pocket left in the core from when they flushed the system. He said that the heater hose should be so hot you can't hold on to it. I looked that up and there are others who have had that problem. It would be nice if it were that simple. I'm going to try that tomorrow.

Of course if I won that 1.3 Billion dollar lottery I would pay someone to fix it

Some would say buy a new truck But, other than the heat this old truck runs good. I could use that $60k to help a lot of people.

 

Maybe your heater core is all clogged up.

Have you tried to flush the heater core from the outlet pushing all the stuff back out the inlet?

If you do this make sure you disconnect the inlet hose and collect everything in a bucket so you don't put all the crud back into the system.

 

My plan when I get home this evening is to do just that. Actually I'm going to flush it both directions to make sure that the air and crud out. I have to do something....in the low 20's all this week. The wife will get more and more unimpressed as the week goes on. What makes it tough is we work at the same place and ride together. That means you get to experience the displeasure both ways along with your on freezing cold experience

 

If it's in the low 20's, you better get some antifreeze in there. Buy full strength, not premixed.

 

I have a 2000 f150 and a 01 f150 Harley Davidson Edition the heat went south. I tried just about everything I could think of on both vehicles I back flushed both cores and had the water flowing well what I think happens is the core has a couple of ventura tubes that are letting the water thru I cut into the plenum box to feel the core and it was hot but what I found is if it is working right it will burn your hand if you touch it so I determined I need a heater core and they want like a $1000 to replace it. So I decided being my air cond didn't work on 2000 I cut the lines and ran new heater hoses to my air cond evaporator now I have heat that's so hot you have to let the windows down for about $20.00 that's for hoses and clamps. The evaporator is like a small radiator. BE Sure to discharge Freeon gas before attempting this procedure.