No heat in my 89. Heater core has never been flushed. Is that likely to be the problem?

 

There's a few things that could cause no heat... have you searched the forums at all? Many, many topics out there about diagnosing no heat.

I'm at work, so don't have the time to search for you right now..

The "google" option in the search function works pretty well though.

 

Thank you.

 

Before you flush, check to see if your heater control valve assembly is opening and closing when you change the temperature control lever from cold to hot. Mines was seized closed due to rust.

 

 

That is exactly the problem. It will pull the cable when moved to cool, but will not push when moved to heat. I lubricated the cable and worked by hand. At this point it still will not push the cable when moved to heat. I'll keep working on it. Thank you.

 

I pulled mines open with needle nose pliers and likely will leave it on heat until after winter. I plan to replace the assembly after deployment next year. It costs $91 on amazon.

 

Did the same thing, I leave the valve on heat, but oddly enough when I turn on the ac and cool air still works great even though my valve assembly doesn't move, I think the internal vents open and close to stop the warm air possibly. I flush my heater core about once a year before winter comes.