defroster works now, not later....

[gramps77]

Sometimes I have to slide the lever back and forth then other times it will just start working on its own after about 5 minutes. I replaced the selector levers with a new aftermarket one from LMC. I didnt replace the vacuum line box that goes on the back of it. Are those prone to cause this issue or does the truck just need to warm up before the defroster starts blowing air out the defroster vents?

[donut]

I'd prob start with the vacuum line from the engine to the firewall and look for crack/breaks.
The junction box shouldn't be an issue, but they're cheap if your in the area..
PO on my truck removed the vacuum junction, when it was re-installed, it was upside down. Flipped it over and voila!! actuators work.

[cory d]

A/C truck? i would just go through all the vacuum lines. when its cable diven some times the ends o fteh cables can pop off and the doors flop around adn have a mind of their own

[gramps77]

Yes its an AC truck. I suppose I'll ck all those lines. It just seemed weird that when it does work, it works great.