1999 ford f150 only blows cold air, blend door works fine and the heat core is getting hot. I moved the temperature dial towards cold the other day and the heat hasn't worked since. Please help. Thanks

May a a vacuum or electrical problem that actuates the blend door.

Check the water hoses from your heater when the engine has run and is hot. Both heater hoses should be evenly hot. If the water valve is the problem, one hose will not be hot because the water is not circulating. If both hoses are hot, the dash ductwork is the problem.

The blend door motor should not have its own fuse.

I like that you were knowledgeable to check both coolant lines tells me you are getting hot coolant through the heater core next thing to check will be the blend door on the inside of your vehicle. The blend door is a door that switches from cold air duct to heater duct depending on what you are using at the time. If it is stuck on the cold air duct you will not get any heat sometimes these doors are vacuum actuated and sometimes they are electrically actuated most the time you are able to see the movement of the motor from inside if you don't see any movement but you hear it move chances are it is the door blend I hope this helps.

Check for correct coolant mixture. Also you could have a thermostat that is stuck completely open causing it to flow straight threw the engine block, cylinder heads, heater core, an radiator without stopping long enough to heat the coolant up to provide cab heat. It could also be a clogged heater core. Or a blend door on the HVAC box that is not allowing the heater core door to open. Hope this helps.

If you are sure the engine is getting up to temperature then your problem will be a part called the electrically positioned blend door and or the little motor that moves the blend door. The blend door moves back and forth between the AC core and the heater core to provide a mix of hot and cold air or hot or just cold depending on what you set the air temperature control at, blue being cold and red being hotter. This is all to common a problem on Ford rangers and Explorers which share the same components of the heating and AC systems. When the door fails it is usually on the cold setting position. The kicker here is that you must remove the dash to replace the parts, the blend door and the blend door actuator motor should both be replaced at the same time, the common reason for the motor to fail is a sticking hard to move blend door due to warping of the plastic it is made from.

there are few things you need to check out:
1. if the compressor is overcharged it will shut down and you won't get any cool air
2. the thermostat for your cooling system is bad
3. the link to adjust the temperature is too short (did you feel the switch loose when changing temperature from hot to cold)?
hope this helps.

I ASSUME THIS IS A 98, THIS PROBLEM IS CAUSED BY A PART CALLED AN "AIR TEMPERATURE CONTROL BLEND DOOR ACTUATOR MOTOR" THIS MOVES A DOOR BETWEEN THE COLD AIR FROM THE AC AND THE HOT AIR FROM THE HEATER CORE, YOU WILL NEED TO REPLACE THAT ACTUATOR. .

your problem is caused by the air temperature control blend door actuator motor being defective, the little motor moves the door that gives either hot air or cold air or a blend of the 2.

where is the heat blend door located 97 ford e-350 van

try changing the thermostat if thats not it check and see if you have water leaking in the passenger side floor board if so then you need a new heater core