No Heat 1996 Mark VIII

squirell

squirell

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Hi Guys,
My 96 Mark is not blowing any heat at all..car runs fairly cool (between O and R on temp gauge in 90 degree plus weather).
Did the self test on HVAC unit and code came up "2"

After this operation I noticed fuse #6 was blown (keyless entry,courtesy lamps,dome lamp switch,memory seat,power mirrors)

(I don't know if the self test had anything to do with it or maybe just coincidence )

Anyway I checked all around the internet and Mark VIII sites and all that came up was blend door 97-98 mark.
I looked for all the fixes and took the dash apart and glove box down ,
but apparently 96 is totally different then 97-98 because nothing was the same as described and on you tube vids.

Any suggestions ?
 
The blend door actuator motor does indeed go bad on Gen I's, my old 96 went out way back in 2005. Blend door motors for Gen I's are obsolete, but there is a solution:

Final Solution. As a last resort, before going the junk yard route, our super mechanic, Gary G., bought a "NEW" Blend Door Actuator for a 1997 Mark VIII; Motorcraft Part #YH-1842 (Ford Part #F7LZ-19E616-AD). He opened it up and the gear that everyone loses teeth on is a perfect match for the 1996 actuator. It is also the upgraded "hard black plastic" instead of the softer nylon gear in the original actuator. The new gear that was put in my original actuator is a double gear in 1 piece (small diameter gear on top of a large diameter gear, both 1 piece together).
The small electric motor spins a brass worm gear, that in turn spins the double gear that the teeth were sheared off.
Long story short, if you have a 1993-1996 Mark VIII with a stripped gear, buy a NEW Motorcraft Part #YH-1842 (1997 Mark VIII actuator). Use that new gear in your original actuator and it should work for you also. The rest of the 1997 actuator did not work in my 1996.
Click to expand...
 
Also check the passenger side of the firewall. There is a vacuum line, hard plastic, that can wear/break and cause all sorts of HVAC problems.
 
marked8 said:
The blend door actuator motor does indeed go bad on Gen I's, my old 96 went out way back in 2005. Blend door motors for Gen I's are obsolete, but there is a solution:
Click to expand...

Thanx for this info.
I don't know where the gear even is ....it's not behind the clock /message center like a gen 2.
I looked at you tube vids....took my dash apart and it's not the same
 
squirell said:
Thanx for this info.
I don't know where the gear even is ....it's not behind the clock /message center like a gen 2.
I looked at you tube vids....took my dash apart and it's not the same
Click to expand...

Actually the box is in almost the same location as the gen II, but it is a different design. It has no arm attached to it. The gear that needs to be replaced in the box is internal. Diagram (courtesy of Driller):

blenddoor.jpg
 
marked8 said:
Actually the box is in almost the same location as the gen II, but it is a different design. It has no arm attached to it. The gear that needs to be replaced in the box is internal. Diagram (courtesy of Driller):

Thanks for the info....drove the car today 1st time since messing with it last week.
heat is working.Maybe I jiggled something ? Cycled it to heat about 10 times, so I guess it may have been just stuck or something from not being used.
I hope it continues to work...really would rather spend my time on the Mark doing better things then taking the dash apart !
Click to expand...
 
Glad it is working again for you. Yes, it is a PITA and I have done it on both my old 96 and my 97
 
I'm not exactly too sure on the exact differences from 1st Gen to 2nd Gen as I've only owned one 1st Gen('94) and wasn't intimate with it as I am now with all my 2nd Gens, but maybe you can look underneath the glove compartment for a gray plastic tab with a thin piece of metal attached to it and check if it moves when you change the temperature on the EATC. It'll be close to the transmission hump and will move UP when on cold and DOWN when on hot.

If it turns out that it won't move when controlling the EATC, then you'll have to do it manually and GENTLY pull the gray tab down with your finger and you'll have heat again.
 
Scallywag said:
I'm not exactly too sure on the exact differences from 1st Gen to 2nd Gen as I've only owned one 1st Gen('94) and wasn't intimate with it as I am now with all my 2nd Gens, but maybe you can look underneath the glove compartment for a gray plastic tab with a thin piece of metal attached to it and check if it moves when you change the temperature on the EATC. It'll be close to the transmission hump and will move UP when on cold and DOWN when on hot.

If it turns out that it won't move when controlling the EATC, then you'll have to do it manually and GENTLY pull the gray tab down with your finger and you'll have heat again.
Click to expand...

Thanx,
I saw that posted somewhere on the board during a search...must be for a gen 2
I just went out and looked again and don't see anything like you described.
Also I can't see anything moving either under or behind the glovebox when turning the temp all the way up then down
 
squirell said:
Thanx,
I saw that posted somewhere on the board during a search...must be for a gen 2
I just went out and looked again and don't see anything like you described.
Also I can't see anything moving either under or behind the glovebox when turning the temp all the way up then down
Click to expand...

No, the Gen 1 unit has no external arm. Usually you will hear a clicking noise from behind the message center which is the stripped gear trying to move the blend door.
 
marked8 said:
No, the Gen 1 unit has no external arm. Usually you will hear a clicking noise from behind the message center which is the stripped gear trying to move the blend door.
Click to expand...

I know...I have searched high and low for an external arm.
I'm gonna say my problem isn't a stripped gear only because I have never heard the clicking from my car.

(I know the sound well,at work we have a fleet of 25 Fords and it's still a problem)

Today I had no heat going to work....coming home it was fine.

I left it at 90 degrees on defrost when I shut it off...hopefully it will work on the condensation tomorrow morning.
I don't know what else to do
 
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