Topic: Heater - no heat...just cold air?

[Yota Up]

The other guy has a problem where his fan doesn't blow.
Mine blows just fine - except it won't blow hot air.

The coolant system is perfect.  Heats up and stays warm.  Hoses at radiator are HOT.

The hoses associated with the heater are not hot - big problem.
When I turn the switch from COLD to HOT on the control inside, the valve piece moves under the hood - so I don't understand why the hot is not running through it.

Seems like a mechanical problem, but by chance could it be something electrical, like a relay or fuse or something?

85 4x4...

[Tallchevy]

Your heater core might be plugged. Disconnect the hoses that goto the heater core & try to blow air through the heater core. Visually look in the heater control valve & make sure when the ar turns that it opens & closes. You might have an air bubble in the cooling system. Make sure the cooling system is full & with the heater valve in the open position, run the engine until the t-stat opens then top off the cooling system

[Yota Up [OP]]

I recently put in a hot shower system.  Basically put it inline to heater system.
However, everything worked perfect the first time I used it.  Then it sat, now no work.

I suspect the air in the system.  How to remove it?

Either that, or maybe the added line in the heater system is too long now - so that it can't travel the length due to lower pressure???  <-doubt it.  I think it's the air problem...

[Tallchevy]

You might have an air bubble in the cooling system. Make sure the cooling system is full & with the heater valve in the open position, run the engine until the t-stat opens then top off the cooling system

Leave the radiator cap off when doing this 

[Rocksurfer]

Pull the heater core return hose and see if it pumps coolant out, if it does that's not the problem. Next move the lever inside the cab from vent to heater and that should work...... maybe you want to try this in reverse order.

[RRMike]

Had the exact same problem.  Plugged heater core.  Pull both hoses and stick a garden hose up to the return line and have a helper turn the water on.  You want to blow water backwards through the core.  Mine puked a ton of muddy looking junk out for about 5 sec then cleared up and now it's HOT air coming out.  Took all of 10 mins to fix.