2002 Expedition 5.4, 135k heater is not working(front or back) and I'm only getting cold air.

I used a Dremel to cut a small hole in my air plenum(sealed with jb and hvac aluminum tape) so I could get my eyes on my blend door before I ripped my dashboard apart. Much to my surprise my blend door was moving back and forward just fine when I adjusted the temperature on my dash. All of my vent selection controls are working fine and I can cycle floor to vent and everything without issue (although I swear sometimes it doesn't want to work, that's why I peeked at my blend door).

I did a full system flush and water flows both directions through the heater core no problem. If I let the car idle it reaches operating temperature and stays there so I know my thermostat is fine.

Why don't I have heat? I hear the ac compressor kick on when the vent selection is just on "panel" and not ac. Could my manual climate control ***** really be bad? I don't think I've ever seen these be bad I'm any vehicle in my life. Any thoughts?

Thanks, Steve

 

Since the blend door moves your climate control is likely working fine. I'd focus first on engine temperature. When you say it's reaching temperature are you going by the dash gauge or are you taking a reading off of the thermostat housing?

 

Thank you so much for your reply. I was referring to the reading on the dashboard.

 

You can't trust that in a no heat situation. Use one of those laser thermometers and take a reading off the t-stat housing. It should be up around 190 degrees. Even 10 degrees too low will make big difference in heat this time of year.

 

New thermostat this morning. Still no heat. Lines are hot going in and out.

 

If both lines to the heater core(s) are hot and the blend door is operating correctly so that airflow is directed through the heater core, you'd have plenty of heat. Therefore, at least one of your observations is incorrect or incomplete.

 

Define "hot". Are they comfortably hot where you can hold them for a period of time, or are they burning hot where you're lucky if you can hold them for even a few seconds?

 

You can still have flow through the core and no heat due to the design. Take it to someone to flush the core with something like lime-away GEL. Nothing caustic - the core is aluminum. If you have rear ac, you have another core there too. The entire system should be flushed as well to get flakes of cast iron from the block out of the cooling loop and once it's clean and working again, I'd suggest a cooling system filter.