Heater Stuck on Hottest Setting Due to Broken Heater Blend Door on Mercury Mountaineer

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.

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Average mileage: 122,007 (15,000–230,000)
14 model years affected: 1997, 1998, 1999, 2000, more2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
91 people reported this problem
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Viewing 1 - 20 of 49 problem details
2005 Mercury Mountaineer 167,000 mi,
Its actually stuck on cold with a click sound
2005 Mercury Mountaineer 182,000 mi,
Blender door open on cold side. Not good timing in winter.
2005 Mercury Mountaineer 137,770 mi,
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!!!!!!
heater blend door not working. found broken vacuum line between firewall and engine. Repaired with plastic tape now works fine.
2007 Mercury Mountaineer 84,000 mi,
Air conditioner ;lows heat on passenger side. Driver side cool.
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.
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
Blender door broke - no heat in front of vehicle
2003 Mercury Mountaineer 124,000 mi,
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
2007 Mercury Mountaineer 82,000 mi,
passenger side air conditioner blows hot air.
2005 Mercury Mountaineer 65,000 mi,
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.
1997 Mercury Mountaineer 222,500 mi,
No Heat in side Mountaineer.
2003 Mercury Mountaineer 117,000 mi,
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.
2004 Mercury Mountaineer 110,000 mi,
Hasn't been fixed yet but reading the source of the same problem of my vehicle not blowing hot air, let's me know it's the actuator.
1998 Mercury Mountaineer 196,000 mi,
vent door needs replaced
Problem with the heater blend actuator. When I want heat only cold air comes out. Makes a clicking sound all the time. I got if fix before and it worked for a while then it started again.
1997 Mercury Mountaineer 15,000 mi,
I had this repaired already and now 5 years later I am having to do it again! The first one cost me over $600.00 and now I am having to do it again? Cheap product!
Clicking noise coming from the dash, then the ac would blow cold from driver's side and hot on the passenger side. Be careful to get your correct part, as any actuator will not work. I ended up ordering the part from rockauto.com, but it was the actuator listed for a 2005 Lincoln Aviator.
2008 Mercury Mountaineer 120,000 mi,
Heater blend door broke. Took to shop to have it fixed.
1997 Mercury Mountaineer 202,365 mi,
Heat blend door half-break where actuator inserts. Ordered a replacement kit from Heater Treaters. Metal construction and instructions on how to replace without tearing dash apart.