Heat blows in back, but only seeps out the front

[wwiding]

You guys have already been a tong of help in fixing up my Mercury Mountaineer. We've had a few cold spells these last few days so I turned my heat on. The heat blows just fine out of the back vent, but doesn't blow out the front vents at all. I can feel the heat seeping out, and my windows will defrost but it takes them forever. The heat worked great when I bought the truck, as did the air conditioning.


When I turn the wheel that controls the fan speed, I can hear a click some where near the glove box. My coolant is full and I don't have any issues with the truck overheating. The heat blowing out the back vent is hot, but doesn't get hot until I drive.

 

[koda2000]

Broken blend door or bad blend door actuator most likely. Do you have the manual or automatic HVAC controls?

 

[wwiding]

Broken blend door or bad blend door actuator most likely. Do you have the manual or automatic HVAC controls?

I have the automatic HVAC controls.

 

[Turdle]

when you select vent, does any air come out the vents, or does it still blow from defrost and floor only?

 

[koda2000]

I have the automatic HVAC controls.

Then you may want to begin by running Ford EATC diagnostics.


Have you been hearing any clicking/cluncking sounds coming from the area of the glove box?

If you mean that the air is coming out the defroster vents then you have a vacuum leak. The defroster vents are the default setting when you loose vacuum.

 

[nameskreen]

If you don't have any air flow from the front, then it's probably the blower motor. I just changed mine, I had air flow in the back but not in the front. If you Do have air flow, but it's not hot, then it's probably a blend door problem

 

[wwiding]

Then you may want to begin by running Ford EATC diagnostics.


Have you been hearing any clicking/cluncking sounds coming from the area of the glove box?

If you mean that the air is coming out the defroster vents then you have a vacuum leak. The defroster vents are the default setting when you loose vacuum.

I get a clicking sound from the glove box.

 

[wwiding]

If you don't have any air flow from the front, then it's probably the blower motor. I just changed mine, I had air flow in the back but not in the front. If you Do have air flow, but it's not hot, then it's probably a blend door problem

I'm getting a new gas tank put on this weekend. I'll look into replacing the blower motor as well

 

[wwiding]

when you select vent, does any air come out the vents, or does it still blow from defrost and floor only?

The air will come out of the vents, just not with much force.

 

[nameskreen]

i was able to get mine to work temporarily by tapping on the blower motor under the hood with a broom handle, that made it pretty easy to be certain that was the problem

 

[wwiding]

i was able to get mine to work temporarily by tapping on the blower motor under the hood with a broom handle, that made it pretty easy to be certain that was the problem

I'll give that a try. Thanks for the suggestion.

 

[koda2000]

I get a clicking sound from the glove box.

Ahhh, then I know exactly what your problem is. A stripped gear in the blend door actuator. The least expensive replacement is the Dorman 604-201 replacement actuator, which can be had on eBay for under $12. A Motorcraft replacement is over $50. I need 2 of them.

Link below:
HVAC Heater Blend Door Actuator Fits Ford OE # F87Z19E616AA Dorman 604-201 | eBay

Note: It comes with a plastic plate on the bottom which you simply snap off before installing. The following was posted today by member @bgk ...

"I went through a lot of trouble replacing my blend door actuator and wanted to help others who might be in this boat so posting this in all the places I searched the topic -- it is mentioned in many posts but the SINGLE MOST important thing to know up front in my case: know which type of HVAC system you have (EATC/automatic has the digital screen with buttons for temp settings; Manual just has knobs you turn manually) and then ENSURE the actuator you buy matches that type of system. Duh! It's not super easy to clarify, so take the time to ensure it's a match. In my case both types showed up as a perfect MATCH for my vehicle on the auto parts site, and not knowing any better I bought the cheapest one (which it turns out was for manual, which I do not have). Both types of actuators look exactly the same and even have the same plug configuration so you'll hook it up and think it's a perfect match, but unless you get the right one it will not work! You'll check fuses and waste time thinking you've got a short somewhere and read a thousand threads when all you had to do was buy the right type! For my 99 Eddie Bauer, the Dorman 604-201 worked first try once I knew the difference (it's EATC). The 604-202 Did not work (it's manual -- and unfortunately that's what I bough first). To add to the confusion, the 604-201 had an extra plastic base fitting attached to the unit, so online and in person it looks totally wrong, but that base fitting just pops off and viola it's perfect! P.S. If you can swing the blend door when the actuator is installed, there's a problem with the actuator -- the "D" shaped post should not move manually. If it does, sounds like the teeth are all busted inside the actuator. If you force it, you will break said teeth."

 

[wwiding]

Ahhh, then I know exactly what your problem is. A stripped gear in the blend door actuator. The least expensive replacement is the Dorman 604-201 replacement actuator, which can be had on eBay for under $12. A Motorcraft replacement is over $50. I need 2 of them.

Link below:
HVAC Heater Blend Door Actuator Fits Ford OE # F87Z19E616AA Dorman 604-201 | eBay

Note: It comes with a plastic plate on the bottom which you simply snap off before installing. The following was posted today by member bgk...

"I went through a lot of trouble replacing my blend door actuator and wanted to help others who might be in this boat so posting this in all the places I searched the topic -- it is mentioned in many posts but the SINGLE MOST important thing to know up front in my case: know which type of HVAC system you have (EATC/automatic has the digital screen with buttons for temp settings; Manual just has knobs you turn manually) and then ENSURE the actuator you buy matches that type of system. Duh! It's not super easy to clarify, so take the time to ensure it's a match. In my case both types showed up as a perfect MATCH for my vehicle on the auto parts site, and not knowing any better I bought the cheapest one (which it turns out was for manual, which I do not have). Both types of actuators look exactly the same and even have the same plug configuration so you'll hook it up and think it's a perfect match, but unless you get the right one it will not work! You'll check fuses and waste time thinking you've got a short somewhere and read a thousand threads when all you had to do was buy the right type! For my 99 Eddie Bauer, the Dorman 604-201 worked first try once I knew the difference (it's EATC). The 604-202 Did not work (it's manual -- and unfortunately that's what I bough first). To add to the confusion, the 604-201 had an extra plastic base fitting attached to the unit, so online and in person it looks totally wrong, but that base fitting just pops off and viola it's perfect! P.S. If you can swing the blend door when the actuator is installed, there's a problem with the actuator -- the "D" shaped post should not move manually. If it does, sounds like the teeth are all busted inside the actuator. If you force it, you will break said teeth."

Hey thanks for the tip. I just tried the EATC diagnostics and didn't get any error codes. I've got a friend coming over this weekend to help me put a tank in. I'll probably get the heat fixed then. I appreciate the help.

 

[koda2000]

The blend door actuator is located behind the glove box. Drop the glove box door by squeezing the sides in. The actuator is a black box with a wire connector on it. It's held in place by 3 small screws. 2 on the front and 1 on the rear. The one one the rear is a ***** to get at. I've done it before, but the next time I'm skipping that screw. It's really not necessary. The actuator has a "D" shaped hole on it and that's what fits over the "D" shaped post on the blend door.

 

[wwiding]

The blend door actuator is located behind the glove box. Drop the glove box door by squeezing the sides in. The actuator is a black box with a wire connector on it. It's held in place by 3 small screws. 2 on the front and 1 on the rear. The one one the rear is a ***** to get at. I've done it before, but the next time I'm skipping that screw. It's really not necessary. The actuator has a "D" shaped hole on it and that's what fits over the "D" shaped post on the blend door.

Yeah I watched a video a second ago on YouTube. If I have to replace it, I'll probably skip that screw too.

 

[koda2000]

Once you have your old blend door actuator off, you can take it apart and remove the large crescent shaped gear. Then you can place it in the blend door post and move the blend door open/closed to check it's movement/operation. Towards you is heat, away from you is A/C.

It's typically the smaller worm gear on the electric motor that strips.