iowaredneck

I woke up this morning to having no heat in my 97 4.6L 150. Could it be a bad thermostat or heater core. It worked last night just fine but not today.

FOMOCO466

I had the same problem, except mine would change when I hit the gas, or the brakes.... in the center of the dash, just above the floor is the heater box, inside there is a $9.00 flapper door that decides hot or cold air... mine broke where the door sits onto the switch. I had to take the WHOLE dash out from door to door to get the top of the box off. I thought it was the actuator which is pressed between the bottom of the box and the floor,,, but when I got it open I found the broken parts. Got the whole assy from FORD for 13.00, and only needed the door(9.00) part of it. Took a week getting to it and then back together..... Go by the manual, cause there is stuff hidden everywhere. HOPE it's not that..... but it's what was wrong with my 99 Expedition.

Good old Bill

Could be either t-stat or blend door. T-stat if the engine temp gauge stays low, blend door if the gauge says normal but still no heat. If the heater hoses have near the same temps, would tend to believe the core is OK.

iowaredneck

Thanks for the help. Is the blend door that hard to change?

Good old Bill

Have never attacked the problem, sounds like a chore according to FOMOCO, am still assuming engine temp is normal and hoses are the same temp. Before someone gets on you, double posting isn't necessary immediately.

iowaredneck

Yes the hoses and engine temp are normal.

FOMOCO466

OK on my 99 the blend door is in the middle of the dash, judt above the carpet in the heater box. THE WHOLE DASH HAS TO COME OUT!! from door to door, airbags ect.... it was a week long job for me to do after work, just to change a 9 dollar part. I had the auto temp control.... you can check it somewhat.... I'd get on the gas hard and see if heat came out from anywhere.... same with getting on the brakes... trying to get that door to move to know for sure. That's what led me to the door....the end where the door sits on the actuator was broke in 5 spots... works like a champ now, but it's a task.... get the manual though.. you'll need it!

iowaredneck

Thanks for the help. I will have to try your trick and see what happens.

skibum7982

My blend door broke a couple years back and here's my poor-man fix that still works(knock on wood). My theory was that I couldn't break it any more!

Remove plenum cover(center cover, under dash). You might also need to remove the floor ductwork, but I think you can get by without doing so.
Remove glovebox.

Take a Dremel with a cutting wheel and cut a nice big hole in the heaterbox(it's black) above where the blend door actuator is (down by the floor). If you don't see it, turn the key to on and with the radio/fan/etc off(quiet), turn the heat from hot/cold...with your head down there, you'll hear it turn if it works. WHo knows, maybe your actuator is the problem...that can be unbolted and a new one put it.

Also cut through the plastic that was behind the glovebox. Once the box goes back together later, you'll never see it anyway. Here you can cut a massive hole, big enough to reach your arm in.

Once the holes are cut, you can see inside with a flashlight if the door is broken. Gotta love plastic parts!! I was able to feel around, gather my pieces, clean them up, then epoxy them back together before assembling it all back inside the heaterbox on top of the actuator spindle.

Give it a day to dry before doing anything with the truck. once dry, try turning the heat/cold ****...you should see the door move. If everything is working again, take some JB Weld or some more epoxy to glue the "windows" of the heaterbox back on. Reassemble the floor plenum and reinstall the glovebox.

You should be back in biz without coughing up $1200 to the dealer for their fix. If it doesn't work, well...it was worth a shot anyway. Goiod luck!

jgee747

hi is your truck a 99 f150 i have some heat but when i turn the fan it disappears . if this works iam very gratefull for the tip jgee747