No Heat

I replaced the heater coir on the 94 last year, and 2 mustangs in years past I didn’t take everything out but it did require you to drop the Steering remove A/C controls, stereo, console, and pool the dash out about 10 inches and up. Sounds like the same process for the Blend door. If I have to do all that for the Blend door it would be poor judgment not to remove 4 screws and the 2 hose clams under the hood and do teh heater coir at the same time. Knowing my lucks as soon as I reinstalled the dash that would be this time the coir would go out and is have to do it all over again because I didn’t spent the extra $40 on a coir at the same time. Heater coir and radiators don’t last forever and I rather do it in my driveway than out of town.
 
Frank, the main difference is you wouldn't take the heater box out. You can not remove the heater box to get to the heater core (not coil) without removing the dash or atleast almost completely.
 
Did they change the 98 from the 94 because on the 94 there is a little panel about 6x3inches that you remove 4 or so screws and the coir slides out without removing the box? BUT yes the dash must be lifted out of the way. Can’t tell from the pic but I believe that this is the panel
 

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That panel is the heater box WITHOUT the blend door "motor" attached. The blend door arm (black) and rod (rusty metal) and recirculation arm (grey) ar there, but the empty screw holes are where the blend door would attach (just above left middle finger and above and left of right middle finger). This is NOT where the heater core is. :) Just face it....you're fighting a losing battle, lol. I totally agree with your thought process, but doing a heater core in the 1 1/2 hours it took me to do the blend door is NOT feasible. Sure, add 2 hours on top of that and you can do the core as "preventative maintanence" but its another 2 hours fixing something that may never break. Might as well replace the blower motor, air suspension module, radio antenna coaxal, and the vacuum lines to the a/c module while you're replacing the heater core. :p
 
I have been on the Mark VIII forums for 13 years, with the blend door it is not a matter of if it will brake but when. I can't recall too many heater core failures if any at all. That being said I think he should go ahead and change it, with all this back and forth for sure we have jinxed him :D
 
Lol. I did go look at my 94 it looks like they did change the 98, I guaranty on the 94 that is the location. I have changed 4 coirs after they went out on me. 2 mustangs, 1 land rover and my 94 mark viii. It may be because I’m in Texas and it gets a lot hotter and there is a lot of dust in the air helping them to corrode. Heater cores are a problem in Texas like rusted bodies up north. you would be suprised how many cars are fo sale with no heat becous the coir was bipased.
 
Yes, they changed the entire air trunk between first and second gen. First gens only have one blend door, the second gens have two. That's why we have those arms on second gens: both arms work together using one actuator motor. First gens don't have those arms, hence they rarely break.

It annoys the piss out of me when people use the term "blend door" when referring to the actuator motor. That's not a blend door, it's a damn actuator motor! I think I'm gonna cut open that air trunk in the picture so everyone can see what's inside. The blend doors are inside the air trunk. You'll never see them unless you pull the whole thing apart. Sorry, just had to rant.

Greg - seriously - there is no need to replace the heater core unless it's leaking. That's like doing a heart transplant at the same time as an appendectomy because "you have to cut the patient open anyway". There are only a few fasteners and one plug to pull in order to pull the dash out the six inches needed to replace the actuator. In order to replace the heater core, you've got to completely remove the dash from the car, which means all the fasteners along with a few dozen wire harnesses to unplug (not only from under the dash but in the engine compartment and under the car), and all the hassle of putting it back together. The "PITA levels" between the two are like a 3 and a 9.

Look at it this way: I guarantee you that once you replace the blend door motor, you'll have the first part of the dash removal down to half the time, and it'll go much smoother in the unlikely event that you need to replace the heater core. But have at it if it makes you feel better.
 
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Yes im seeing it now. I quess Ford didnt like people fixing there owne cars so they made it harder to work on. I was suprised when i changed the core on my 94 that it had a cover and it was as easy as it was. That was the confusion i had worked on my 94 when everyone was talking about a 97-98. If the the 98 ac was like the 94 it would only be 10 more menits to change the core. I guess i owe everyone a beer now.
 
All that had to be seed was that they changed design for the 2nd gen. So anyways I believe it’s the gears in the actuator that are bad. Has anyone figured out a place to get parts and rebuild the actuator instead of buying new? I’ve seen a picture of one opened up and it looked like a cheap RC car motor and gears that you see in kid’s toys all the time. There has to be a place we can get all the little gears for 25cents each. If it’s the motor I bet Radio Shack or Fry’s or a hobby shop. I bet we could make a little cheep rebuild kit.
 

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I thought it was the arm that cracked, which allowed the "drive shaft?" of the motor to move without moving the attached arm... :rolleyes:
 
BadSax said:
I thought it was the arm that cracked, which allowed the "drive shaft?" of the motor to move without moving the attached arm... :rolleyes:
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You are correct sir.

shaft_fracture.jpg
 
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Blend door # 2

Blend door # 2

J said:
Just FYI. I'm working on a revised blend door write up. You DO NOT have to remove the dash so ichsnea the heater core idea. :)
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I would also like to receive a copy of your revised blend door write-up when you have it finished. In 2005 a dealer replaced mine on my '97 Mark (53k miles) to the tune of $453. Now with 78k it is bad again. If it is not necessary to remove the dash, I'll do it, so, I look forward to your report as it is cold up here in MN. Thanks for helping.
 
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