FJ heating issues
 

Hey FJ folks, Got a problem on my buddie's cruiser I was hoping to get a bit of help with. He has defrost and heat when he first starts the rig up, but it fades out completely as the rig warms up to temp. The blower motor runs at all speeds just fine, but no hot air. Any clues? I've never owned an FJ, or even worked on one before, just older trucks and 4Runners. Any input would be greatly appreciated as It's starting to get cold enough to freeze in Idaho. Thanks in advance.

On other trucks - probably same as on the FJ Cruiser, these are needed in order to have heat:
1) Hot coolant flows from engine block to the hose on firewall,
2) Heater control valve opens to allow hot coolant flow to flow through the heater core from one hose, and back through the other hose to the engine.
3) The air flow controlled by the heater control slider / knob directs air through the heater core fins so air picks up heat before it gets blown into the cabin.

So the hoses to the heater core are getting warm when and where they should, the heater control valve is functioning as it should, warm air is coming from the vents, but the fan slowly winds down to not running at all as the vehicle warms up. the warm air continues to rise to the windshield defrosting it, but the blower just putters out. Is this a resistor issue or a switch/sensor of some type?

Contradicting statements. Pls clarify.

I got more information from my friend about what was happening. it runs fine until it warms up, the slows down to a dead stop.