OK...Today in about 4 hours is the day that I am going to replace the broken heater core in my 1999 Blazer 2-door 4WD. Gonna take a while I know, but here in KY it has finally become to where the mornings are in the 20's and 30's and I can't stand it anymore. Gotta fix it.

Anyway, while I am at it, I also have the common blend door problem in which the lower blend door going to the floor heat has stopped working. I have verified it is broken, and that the actuator is working as it should. However, where it had broken it also caused the spring to come off.

My question is this: Is the spring supposed to be mounted to where it keeps the door closed, or is it supposed to be mounted to where it keeps the door open? I can't recall as to if the actuator opens the door, or closes the door, but I would assume that the spring on the end of the shaft is going to do the exact opposite of the actuator - i.e., if the actuator opens the door, then the spring is mounted at to where it keeps the door closed.

Am I correct in this way of thinking - and if so - which way does the spring mount?

I dread this job as I know it is time consuming, and I have absolutely no help. I'm going to have to do it all by myself. But the weather has caused me to not put if off any longer. This morning it is 23 degrees. I leave for work at 5 AM through the weekdays, and have been freezing to death on the days it has been in the 30's and 40's. So....today the heater core must go in....

How about the spring? How does it mount? Keeps the blend door open or closed?

Thanks for the help,

HCII