Heater not blowing hot

Got a new problem that i noticed last week. turned on the heater... blows nice and strong but theres no heat. after reading many threads on this issue, i checked coolant level (after reaching operating temp) by adding coolant to the overflow tank... and have been checking it every day since. level seems to be fine. temp gauge never goes high. stays in the normal range (just above middle) so i'm not overheating. which leads me to believe the thermostat is fine.

what else could cause no heat?

 

The water control valve on the firewall might have failed in the closed position.

The cable might have broken . Blend door in closed position

The heater core is so covered in dirt no air will pass through . The internal tubes in the heater core are blocked with rust .

Good luck

 

checking the control valve... it will not move on its own. (looking at the engine, the lever is all the way to the left) and i cannot move it at all. But if i disconnect the cable, i can easily move it with my hand. i moved it to the right but the air still does not get hot. is it supposed to move on its own when i turn the temp to hot (red)? shouldnt the air get hot when i move it with my hand?

 

What year truck?

 

It could be an air pocket in the system. If you said the overflow tank was empty, I would suspect some air in the system.

I would bleed it with one of those no spill funnels.

it could also be a coolant leak somewhere that you wouldn’t see as often like the water pump or heater core

 

The blend door actuator controls coolant flow and airflow to heater core and AC coil.
Door flap may be stuck on AC.
What year truck ?
Some have all cable, others have electric actuators some have a combination of both.

 

2004 pre runner 4 cyl.

i think im starting to understand. i found the HVAC actuator under the dash... passenger side. when i turn the temp dial to hot, the cable does not move. i tapped the actuator a few times then it moved and the air got hot... BUT, THE CABLE WAS STILL DETACHED FROM THE VALVE UNDER THE HOOD. So i dont get why the air got hot if the cable did not open the valve. it looks like i need to replace the actuator. but i'm still confused.

 

Sounds like when you manually moved the valve it’s now stuck in the hot position. When you got the blend door to move, it just switch air moving from the evaporator core to the heater core. Without that actuator in the proper position you will never get hot air, even if the heater valve is in the right position.

 

ah... i see
so replacing the actuator should solve this bc then the air AND water will be in the right position to give heat? (is that right?)

 

yep...

 

Turn settings to AC
Still hot air ?
You can't move the cable from valve by hand unless it's disconnected from actuator.
Actuators with screw covers are serviceable to some extent.

 

gonna remove the actuator today and see if i can open it up and service it. maybe grease it up.

 

Looks like I actually fixed it. Removed the actuator… opened it up… broke like 3 clips in the process… removed the gears and greased them. Bent the contacts upward. Put it back together and reinstalled…. A little tricky getting it back in place… and it works like a charm.

 

Glad you have it fixed.

With my luck I would have another one ready to install.

Mine would quit the coldest day of the year one of those rare -20 degrees F with high winds.