My hvac system seems to work ok, at least the different fan settings and the AC. My problem is I get no heat. It is probably the round cold-heat switch. Any thoughts?

 

No doubt that's where you're problem is if the fan is blowing. You certainly know the engine is heating things up.

Must be a disconnect between the **** and baffle.

 

what year truck???? if it's a newer truck. and your engine is heating to normal temp. and is full of coolant. the most common thing is the blend door actuator.

what year, and make.

 

turn your fan on high, select panel and change the temp setting from cold to high. If you hear a change in the noise that the air makes & you feel slightly (it's not that noticeable) less air coming out of the vents, that means the blend door is working.

IIRC, You can also pull off the center vents and stick a wire down there to feel it the blend door is moving.

 

sorry i just replaced two switches today. sound's like sw. or actuator. good luck.

 

Had the same problem. Check the temp ****. Mine was split on the back and would turn without turning the control.

 

OK, I replaced the cold-hot switch today. No Luck!
How do I check the blend door actuator?
It is a 97, F-150, Supercab.
Thanx

 

read my post above about the way to check if the blend door actuator is functioning.

 

OK, I turned the fan on high, changed the setting from cold to heat, and I heard a slight change in the noise. I believe the blend door is working. The coolant looks a little dirty, how can I tell if it is circulating through the heater core?

 

The cheapest/easiest way to check the flow through the core is to let the engine get up to operating temperature and set your contol to "floor" and the temp control to hot. Pop the hood and find the 2 heater hoses that go into the firewall and feel them. They both should be warm/hot to the touch.

 

OK Guys,
I'm really gettin' frustrated here. I have replaced the cold/hot rotating switch; I have flushed out the system and water does circulate through the heater core; I have checked the air flow when I turn the system from cold to hot and there is a definate difference in the air flow ( it is cut by 75% when it is turned to hot)so it seems as if the blend door actuator is working; NOW WHAT?
Cold in San Diego

 

Have you had anyone else verify that only cold air is coming out?

Maybe you're dead.