What a brutal job this was. Getting the broken assembly out was difficult enough but installing the replacement proved to be even harder. Ultimately I removed all of the defroster duct to gain relatively clear access and that in itself was quite a chore.
I also replaced the heater controls since the originals had dried up and disintegrated. Also going to replace the heater valve o-rings while I'm in there.
Can't get the heater blower to run either so looks like I'll be removing that. I have a parts car with the blower still in it so I'll do that first for practice. I understand this is a very difficult task so any tips would be appreciated.
The dreaded heater blower.
Heater valves
New heater controls
