OK, I intend to do all the obvious stuff like change the t-stat(OEM of course), new filler cap, flush, logicon work, etc. But I thought I could save some time with a little advice. My '86 GXl has no heat!!!!!
Temp gauge reads low, about a quarter way up the meter. Logicon doesn't switch vents, AC works fine, but there is absolutely no heat-more importantly no defrost. Any ideas before I start tearing into everthing?

 

To begin with, these is no such thing as a dumb question only dumb answers.
My first guess is that you have a large air bubble in the system that is blocking moving the coolant into the core. I would first try purging all the coolant, flush the system and refill. I hope it works.

 

Look under the drivers side dash, upthere somewhere is an actuating rod for the heater control, mine have popped off a few times, I dont know why because everything looks allright and nothing is broken
Just reconnect it or move it by hand

 

Thanks!!!!! I'll try all the above this weekend and let you know how I do. ZSW