1994 Ford Explorer Heater Problem

Ideas like a possible sticking thermostat?

That's where my temp gauge has always read when the truck is fully warmed up. Maybe you have an air pocket in the heater core or the heater core is plugged up.

Thanks PeterD, thats what I was considering at first then got to thinking that since the truck was warming up and the temperature gauge was staying consistent then I might need to look elsewhere.

Pulled out the repair manual to have a look at how the heater system is setup and came to the conclusion it might be the heater valve that is attached to the two heater hoses going into the firewall. This was replaced with an aftermarket part several years ago when Firestone broken the OEM one that had become brittle during another maintenance session.

Turns out this fixed it ($18.00 later) and now heat is hot as can be. The aftermarket part seems to be made rather cheaply and this one will probably do the same thing in a couple of years. The valve seems to have a tendency to stick where it slides on the outside on the steel pin.