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1997 - 2003 Ford F150 General discussion on the Ford 1997 - 2003 F150 truck.

heat from vent/AC

Old 05-22-2009, 10:28 AM
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Default heat from vent/AC

I have a 1998 F150 and when I switch the heat/cold **** to cold for just vent air it comes out hot as if the heat was on, it also blows very hot air when the AC is turned on. I don't think its the selector switch because I can hear the air switching in the vaccum lines.
Is anyone aware of this issue?
I'm thinking its the hot cold switch...but I was also told it could be the blend door motor.
Old 05-22-2009, 01:54 PM
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Several other posts about the blend door comming apart. Suggest looking under panel at AC chamber, cycle the heat/cold, watch the actuator and if it moves OK then the door is busted inside.
Old 06-07-2009, 04:15 PM
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Same problem on my 98. Don't think its the **** controller as that is a simple rheostat. I took the door actuator off and found the door works fine. Opened up the actuator plastic and the gears move fine by hand, but no movement from the motor when **** is adjusted. I am assuming that power is fine and its just the motor that's blown. Everything seems to work mechanically.
As a temporary (summer) fix, I moved the door to block the heat and reinstalled the actuator to lock it closed. So now I have full cold AC, but no heat.
For the 98, the actuator is Dorman #604205, $38 at RockAuto.com (not a plug, just my general first resource for parts).
Removing the floor vent and getting the actuator out was a pain in the butt. There's hexhead screw way back under for the floor vent, and 3 for the actuator.
Hope that helps.
Old 06-07-2009, 06:43 PM
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A very common problem with 97' & 98's. Ford has admitted this problem, even has a TSB on it, but won't issue a recall. If your out of warranty, your out of luck. Do a google search on F-150 blend door, you'll be surprised how many F-150 owners are in the same boat.
It's a $700-$900 repair, to replace the door and / or actuator.
I suggest you contact the NHTSA, and add your complaint to the growing list. It may eventually lead to a recall as a safety issue.
Old 06-08-2009, 08:37 AM
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I replaced the **** and as you said still nothing. I guess its time to take the floor vent out and check the door or change the motor. Thanks
Old 07-22-2009, 08:05 PM
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Originally Posted by Good old Bill
Several other posts about the blend door comming apart. Suggest looking under panel at AC chamber, cycle the heat/cold, watch the actuator and if it moves OK then the door is busted inside.
I am having this same problem. I have pulled apart all of the panels under the dash and cannot see an actuator or anything like it for the hot cold. Are you refering to the actuator moving from a/c to feet to defrost etc etc? I did find that actuator.

I think my problem is the blend door but have no idea how to take things apart under there to check. It appears you have to remove the dash to actually get in and see the blend door. Is that correct?
Old 07-23-2009, 03:49 PM
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My guess is a +1 for the Blend door, which is apparently common. I had a similar issue with my Explorer.

There are some explanations of self fixes out there in several of the forums like:
http://www.conceptualedge.com/blend-door/

and I also saw this:
http://www.heatertreater.net/Ford%20F150%2097-04.htm

You can also Google F150 blend door
Old 07-23-2009, 09:01 PM
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The actuator is a small motor contained within a plastic enclosure, located on the passenger side of the lower central dash, right above the tranny hump, where the floor vent outlet is. The actuator box is not really visible, you have to grope around a little and contort yourself to see it and loosen the screws holding it in place. The blend door has an axle that has a + end that fits into a socket in the actuator gearing. Hard to explain, if I get a chance I'll get a photo uploaded.
Old 07-28-2009, 11:33 PM
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Ok, after a few extra hours of searching forums and doing some testing I have solved the problem. I am typing up a little summary so hopefully anyone else with my problem will only have to look in one place to find the answer. I hope this helps.

As you will probably find if you research it, there can be several different problems that cause the hot/cold to stay on either hot or cold. First, it could be a broken blend door. Second, it could be a fried blend door actuator motor. Third, it could be the module connected to the hot/cold **** itself.

The first place I would check out if you are looking to fix this problem yourself is www.heatertreater.net. These guys have an awesome step by step video on how to access the blend door actuator. They also have an easier solution in the event that your blend door itself is the problem.

Repair location....

If you are experiencing this problem the blend door actuator is actually pretty easy to access. Under the dash in the middle of the truck you will see a plastic cover (right on top of the transmission tunnel pretty much on the floor of the truck). It is held on with a couple push in trim bolts. Once removing that you will see the white blend door actuator and the bottom of the blend door box (black). Now you can pretty much see everything and can follow the video on www.heatertreater.net to remove the parts.

After pulling it all apart here are the things to check...

1 - If you remove the white blend door actuator and see black plastic particals fall out, chances are the blend door itself is broken. Obviously you have found the problem at this point and can look into the options for replacing the blend door (Not an easy thing to do if you are not handy with tools on cars).

2 - If no pieces fall out, take your fingers and grab the bottom of the blend door (it sticks out just enough to grab with your fingers). With the vehicle off you should be able to freely move the blend door about 60 degrees from hot to cold. If you can do this then the blend door is fine.

3 - If the blend door appears to be working then the next step is to check the blend door actuator. This is really simple but does require you to turn the vehicle on (some people may not like turning the vehicle on with things pulled apart though). As long as you don't unplug anything except the blend door actuator you should be fine (I was). With the vehicle turned on plug the blend door actuator back in and hold it in your hand. With it uninstalled from the blend door and in your hand you will easily be able to see if it is working. With the car on simply move the hot/cold **** from hot to cold. If you move it and the actuator does not work, there is a really good chance it is the actuator itself.

4 - If the actuator is not working there is a slight chance the **** is the problem. This is not very common and there doesn't appear to be a way to really test this unless you have electrical testing equipment and know what to test for. It is more likely the actuator itself.

After going through this testing I found my blend door actuator was the problem. I went to my local Advance Auto Parts and they had one in stock. For my 2002 Ford F-150 it was Dorman part number 604-205 and cost about $50. Put the new actuator in and now my a/c and heat work perfectly fine.

Hopefully this is helpful for anyone experiencing this problem. Good luck in your repairs.

Ray
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