A failed heater blend door or actuator can cause the temperature control for the HVAC system to stop working. A clicking sound from the dash area would commonly indicate an actuator fault. If the heater gets stuck on the hottest setting, the heater blend door may be broken requiring replacement of the heater box to repair the issue.
Heater Stuck on Hottest Setting Due to Broken Heater Blend Door on Mercury Mountaineer
Average mileage: 123,197 (44,000–230,000)
73 people reported this problem
34 people shared problem details
heater blend door not working. found broken vacuum line between firewall and engine. Repaired with plastic tape now works fine.
first there was a clicking sound, then the heat was stuck on the hottest setting. have called around town and its looking like $340 plus to fix. This is a very common problem with Fords. If the company knows this, they should fix it for free or discount a repair at the dealership. why keep making cars that are gonna have the same problem.
2005 Mercury Mountaineer167,000Visitor
Its actually stuck on cold with a click sound
2005 Mercury Mountaineer182,000Visitor
Blender door open on cold side. Not good timing in winter.
Mine was stuck on heat-no AC-bought aftermarket blend door online-after taking dash out found orig OK, but actuator motor broken.bought one at a national parts place, it wouldn't work, took to shop they replace w/ford actuator-now works, but knob to regulate air flow does not work, will cost another $600 to repair-don't have the $$ to do so
2003 Mercury Mountaineer124,000Visitor
Just purchased from local ford dealership, two days later clicking sound in heater.. took into service dept and was told not to worry about it... now two days later I have no heat.. taking in tomorrow to see what they will do for me
2003 Mercury MountaineerVisitor
Blender door broke - no heat in front of vehicle
2003 Mercury Mountaineer117,000Visitor
clicking when changing to heat, as far as I can tell the blend door actuator gear must have some stripped out teeth on it. The actuater being replaced should fix the problem.
1997 Mercury Mountaineer222,500Visitor
No Heat in side Mountaineer.
2005 Mercury Mountaineer137,770Visitor
My heater started making a loud noise and then it finally went out. I replaced the blend door actuator several times but they kept going out. Everytime I put the actuator in the only thing that will works is my heater. So if I unplug the blend door actuator my air conditioning works. If I plug the blend door actuator in the heater works and my air conditional won't. So in order for me to have air I have to unplug my blend door actuator every summer and in order for me to have heat I have to plug my blend door actuator back in everyone winter which means I have to buy a new one every winter. It's so frustrating don't nobody know what's going on or how the fix the problem please help me!!!!!!
2005 Mercury Mountaineer65,000Visitor
blend door thumps and has troble changing from warm too cold.not fixed dealer told me it will cost a thousands dollars to fix it.
2007 Mercury Mountaineer84,000Visitor
Air conditioner ;lows heat on passenger side. Driver side cool.
Doesn't get cold enough or hot air comes out
2007 Mercury Mountaineer82,000Visitor
passenger side air conditioner blows hot air.
2003 Mercury Mountaineer105,000Visitor
No air flow from heater through defrost, floor or dash vents.
2002 Mercury Mountaineer130,000Visitor
turn on ac its hot then I put on maxac and it gets cold.
2007 Mercury Mountaineer83,000Visitor
passenger side temperature control not working. do not know if pneumatic, electric or mechanical problem
2004 Mercury Mountaineer135,000Visitor
Air conditioning blows hot air.
2005 Mercury Mountaineer130,000Visitor
No heat or cool air. I must keep the dial on the coolest setting or I will get a click click click click noise until I turn it back to the coolest setting.
2000 Mercury Mountaineer221,881Visitor
replaced blend door, however no heat.
my heater blows warm air then cold air,it keeps alternating when i have the heat on
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