Hi everyone.
We have a 2002 Ford F-150 4.2l V-6 with the automatic trans. If the truck is driven for more than an hour or so with the heat on full heat (**** towards full red) the center of the dash around the vents and the radio gets really hot. Inside the tape player gets hot enough so that you can't hold your hand in it. Also it smells of burning plastic once in a while. I am wondering if anyone has any suggestions on this? I don't think it's the blend door because it switches from hot to cold just fine. It just seems like the hot is way too hot. I also couldn't figure out if the heater core has a valve to control coolant flow or not?

Also the truck has a very irregular idle which we believe to be a vacuum leak which has not been found yet. If there is a heater core control valve and its vacuum i'm wondering if the two problems could be related?

Any help would be great as we're a little bit stuck.

 

I would pull the radio out and have someone else drive it so you can focus all of your attention in the radio opening to possably see where it is coming from. At that point you could also use an infra red temperature gun to find the hot spots. You can get one of those guns at Harbor Freight pretty cheap and it would be good enough to find that problem.
Good Luck and post your results!

 

We actually happen to have a thermal gun so I will fiddle with it today and let you know how it goes. If anyone has any other ideas it would most helpful

Thanks guys

 

Might be your Vacuum Control Motor Panel/Defrost Door unit is defective, the door it attaches to is broken or vacuum not getting to it from Heater Switch Panel. There's also the Vacuum Motor Floor/Panel Door unit to check for same conditions.

 

Could you explain what those two things are and where they are located? Also today I got a temp reading at the panel vents and the floor vents. The panel read about 160-165 degrees F and the floor was about 170-175 degrees F. I took a reading on my 2000 Honda Accord and the panel was about 135 and floor about 150 with our 2002 Focus being about the same as the accord. So it seems that the F-150 is putting out way too much heat. (Keep in mind all these reading's were with the temp control all the way on red) So I'm pretty sure its too hot just not sure why?

 

Perhaps you shouldn't run the heater temp **** pegged. I peg mine 1st thing in the morning then after the cab warms I run it at about half way. The motor runs at about 195* and that is where the heater gets it's heat. I don't know-just a thought.

 

I agree with you. In my car (the accord I spoke of) I turn it back after a bit but the truck is my dads and he tends to be a bit cold blooded. I still think its too hot because my car and his focus were soo much cooler. I believe most engines run at similar temps so I would think that they should put out about the same amount of heat or be regulated to do so?

 

You're right. I read the post as if there might be a door position problem. When it's -40 outside you'll be happy to drive with 195* heater core temp to heat the interior from an ice cube. I think the 'panel' position is designed more for the A/C aspect of the HVAC system which may account for the overheated plastics and radio area while under full heat. Most drive using the heater in Floor, Floor/Defrost or Defrost positions. The Floor/Defrost, Defrost positions use A/C as well to help distribute dryer air to the windshield.

yamaha225, According to my book you have to remove the heater cover between the dash and floor hump to access the door vacuum control motors if you want to check them out. Why not just read the owners manual. It should explain which areas air will flow from when each position is applied then check the motors if not correct.

 

Thats probably true. I know in my car i usually leave it on defrost or defrost heat. My father's dead set on taking it to the garage but the more i think about it the more I don't think they're going to find anything so maybe I'll just tell him to leave it on defrost.

 

That's the beauty of having manual controls, you can set it where you want and at what temp level and fan speed. I personally hate heat blowing at my face, it bothers my eyes. I prefer to leave the mode at floor or floor/defrost.


I had a 92 Lincoln LSC that I had bought with high mileage. I had to change the heater core in it. While trying to remove the whole heater assy it wouldn't come away from the firewall even though all the bolts were removed. I finally got it out with some force only to find the top of the heater box plastic had heat welded itself to some upper dash insulation with a hard rubber backing. I can only assume the previous owner had left the heat on Hi temp for an extreme amount of time during warm weather or the auto climate control had a malfunction at one point.

 

Ya it bothers my eyes too, but my dad likes to drive around with the heat out the panel on full heat which i've never understood. Oh well hes still gonna take it in so we will see what they have to say. Thanks so much guys

 

my trucks heater runs hot. I consider that a good thing and just turn the heat down when I cant take the heat.

 

The sensor for my water temp gauge is in the heater inlet hose. It shows 210 deg coolant headed for the heater box ...

 

Alright that tells me its probably putting out the right amount of heat. Thanks a lot

 

The temp will momentarily peak at 235 right before the thermostat opens. If I put my hand to the dash vent at this time, the air is scorching