How To: Dash Blend Door Actuator Replacement 05-09 Mustang

Discussion in 'DIY Tech Guides' started by Dino Dino Bambino, Mar 16, 2021.

Car Parts
  1. Dino Dino Bambino

    Dino Dino Bambino I have a red car

    In total there are four:

    1. Floor/dash vent actuator on driver's side behind gauge cluster (Motorcraft part no. YH 1870).
    2. Defrost vent actuator on passenger side behind the center console (upper) (Motorcraft part no. YH 1870).
    3. Temperature blend door actuator on passenger side behind the center console (lower) (Motorcraft part no. YH 1865).
    4. Recirculate vent actuator under glove compartment next to blower motor (Motorcraft part no. YH 1869).

    I'm going to concentrate on the first two as these are the most challenging and the ones I've just replaced on my '06 GT. So what were the symptoms?
    Firstly I could hear a brief whirring sound from behind the gauge cluster whenever I turned the heater switch in either direction from the 12 o' clock position (bad no.1 actuator).
    Secondly, I noticed that cold air was blowing from the defrost vents as well as the dash vents whenever I'd turn on the AC (bad no.2 actuator).
    Since the plastic gears inside the actuators are known to fail, I ordered all four from Rockauto and kept two of them as spares for a rainy day.

    1. Floor/dash vent actuator on driver's side behind gauge cluster (Motorcraft part no. YH 1870).

    Tools required:

    Small 1/4" drive ratchet with short extension, 7mm & 8mm hex sockets.
    Small but powerful flash light.
    Small hands with long thin fingers.
    Lots of patience.
    Your favorite collection of expletives.

    If you have gorilla-like hands with fat fingers, pay someone else to do the job! Fortunately I don't so I went the DIY route.


    1. Lower the steering wheel as far as it'll go.
    2. Carefully pull the gauge cluster bezel away from the dashboard.
    3. Remove the four 7mm bolts that hold the gauge cluster in place, disconnect the wiring harness from the back of the cluster, and ease the cluster out of the way.
    Floor Vent Door Actuator.jpg
    4. The floor/dash vent actuator will be visible on the right and it's held in place with two 8mm bolts that need to be removed. Begin by wedging an object between the dashboard structural bar and the vent duct to push the latter higher and gain better access. A screwdriver handle or an old gear knob would do, but I wedged in pieces of wood instead.
    The front bolt is easily visible but space to get your hand in and rotate the ratchet is very limited so you'll be turning it a couple of clicks at a time with your left hand. Disconnect the wiring harness first to allow a bit more room for the ratchet. However the rear bolt (white arrow shows direction in first photo) is an absolute bitch to get to and this is where you'll need your collection of expletives. Approaching it from the top will be blind as it's obscured by the vent duct, and you'll need to feel the bolt head and somehow direct the socket onto it (again with your left hand). Turning it loose will be one click at a time and an exercise in extreme patience. If you lie face up with your head above the pedals, you can just about see it from underneath the dash and approach it from that side, but it'll be almost equally as frustrating and you'll be lying in an uncomfortable position unless you elect to remove the driver's seat, especially if you're large framed or very tall. Midgets with long thin fingers will have a definite advantage.
    Behind Gauge Cluster.jpg
    5. Eventually the old actuator will come out and this will be the view.
    6. Take a break, grab a beer, and chill out for a few minutes.
    7. Carefully position the new actuator ensuring that the swing arm pin sits in its slot, and that it's correctly seated with the bolt holes properly aligned.
    8. Insert and tighten the two 8mm bolts one or two tedious, frustrating clicks at a time until they're eventually all the way down.
    9. Plug the electrical connector into the new actuator.
    10. Before you reinstall the gauge cluster and complete the procedure, start the engine and turn the heater control switch to all settings while observing the actuator swing arm to ensure that it moves in both directions.
    11. Breathe a huge sigh of relief and have a second beer to celebrate the sweet smell of success!

    Old part:
    YH 1870 OLD.jpg

    New part:
    YH 1870 NEW.jpg
    YH 1870.jpg

    2. Defrost vent actuator on passenger side behind the center console (upper) (Motorcraft part no. YH 1870).

    Tools required:

    Small 1/4" drive ratchet with 8mm hex socket.
    Small but powerful flash light.

    Fortunately the procedure for replacing this actuator is much easier than the aforementioned and can be completed in less than an hour.


    1. Move the passenger seat as far back as it'll go.
    2. Open the glove compartment, empty the contents, push the sides inwards until the rubber stops clear the recess, and allow the glove box to drop all the way down.
    3. If you look up behind the center console on the passenger side of the transmission tunnel, you'll see two actuators. The upper actuator operates the defroster vents while the lower actuator operates the temperature blend door.
    Defrost & Temp Door Actuators.jpg

    4. The procedure for removing either of the two actuators is essentially the same. The only difference is that the upper actuator has a swing arm (same part no. as floor/dash vent actuator) with a pin that needs to be engaged in the defroster vent swing arm slot during reinstallation, while the lower actuator just has a small gear that needs to slot into place (Motorcraft part no. YH 1865). You'll need to be lying on your back looking underneath the dash to perform this procedure.
    5. Disconnect the wiring harness by pushing in the small tab on the side and gently pulling it out. Move it out of the way.
    6. Using your left hand, loosen the two 8mm bolts and remove the actuator from its recess. Note the position of the swing arm as you remove it.
    7. Insert the new actuator into its recess ensuring that its swing arm pin is engaged in the defroster vent swing arm slot before manipulating it into its final position.
    8. Insert and tighten the two 8mm bolts, and plug in the electrical connector.
    9. Restore the glove compartment to its original closed position.

    To ensure correct operation of the new actuator, the HVAC system needs to be reset. This step is VERY important so don't skip it.

    10. Remove the kick panel in the passenger side footwell to gain access to the smart junction box (SJB). It's only clipped in place so pull carefully and ease it out of the way. You'll need to unclip the front part of the door sill plate first to make it easier.
    11. This will be the view of the SJB from the passenger side footwell.
    Smart Junction Box.jpg

    12. The fuse/relay box is at the bottom. After you carefully remove the cover, this will be the view.
    SMJ Fuses.jpg

    13. Use a pair of needle nose pliers to remove the two 5A fuses as indicated by the arrows (fuses no.10 & 12 in diagram). These control the HVAC system and the fuses need to be left out for at least one minute to reset it properly.
    Fuse Diagram.jpg
    14. Reinsert the fuses into their original positions, clip the SJB cover back into place, and reinstall the kick panel.

    3. Temperature blend door actuator on passenger side behind the center console (lower) (Motorcraft part no. YH 1865).

    The procedure for replacing this actuator is the same as for the defroster vent actuator, but it's much easier to reach without lying on your back facing up in the passenger side footwell.

    4. Recirculate vent actuator under glove compartment next to blower motor (Motorcraft part no. YH 1869).

    This one is the easiest of all to replace as it's under the dash to the right of the blower motor behind the glove compartment, and access is very good if you lay on your back looking under the dash.
    Recirculate Vent Door Actuator.jpg

    PS: I opened up both of the actuators that I'd removed to perform a post-mortem. Both had a broken plastic gear but since it was a different gear that broke in each actuator, I combined the good bits from both of them to create one good spare. :D
    Last edited: Mar 16, 2021
    DieHarder, MrBhp, 07 Boss and 3 others like this.
  2. mpm_1

    mpm_1 forum member

    Nice post thanks for the effort Dino. Hope I never have to do it but great reference.
  3. datmbn

    datmbn forum member

    I have done it 2 times already and ar upp for the 3 time when the car returns from winter hibernation
    I used cheep aftermarket ones that dont last but this time i using Motorcraft hopfully they last longer.
    I think that the potensiometer that tells how far the swingarm has traveld goos bad and then the accurators hits the end stop and destruct them selvs
    regards Mats
    GlassTop09 likes this.
  4. 86GT351

    86GT351 forum member

    Great post. We do a lot of them here at the dealer on all of our cars. Definitely a weak design for sure.
  5. MasterofDisaster

    MasterofDisaster Member

    Nice post. I hate under-dash. You're a braver man than I, Gunga Din.
  6. Hawgman

    Hawgman THE fucking bad guy Staff Member Administrator Super Moderator S197 Team Member

    Great write up man. Thanks
  7. 86GT351

    86GT351 forum member

    Guaranteed to draw blood. LOL!
    crjackson likes this.
  8. Rugermack

    Rugermack Junior Member

    Great write up, I have a #1 on my counter.
  9. DieHarder

    DieHarder Senior Member

    Absolute PITA. I consider myself Lucky I haven't had to do a driver's side yet...
  10. BrianW

    BrianW Junior Member

    Great guides! I’m trying to replace the upper passenger side actuator (tough to get out!) but I don’t really understand where the pin of the swing arm is supposed to go. Could anyone help me with this?
  11. FredB66

    FredB66 Member

    Dino's guide is great but it's still a PITA. When I reclined the passenger seat, head on the floor, legs over the back rest I could reach up and feel the lever arm where the pin engages with my fingertips. After several tries I gave up because I just couldn't get my hand far enough up there. I grabbed my skinny-ass 15 year old son and he was able to get his lankey arm up there and get it the first try, so my first suggestion is, if you're a large person, find someone small.
  12. crjackson

    crjackson Member

    Great guide.
    Over time, the potentiometer eventually gets covered in the grease that lubes the mechanical parts. This leads to a false position signal. With the position unknown or incorrect, the BDA ends up being driven beyond the physical limits of the door, stressing all of the plastic gears, stripping them out or cracking them.
    GlassTop09 likes this.
  13. Alan Russell

    Alan Russell Junior Member

    Thanks for this article, I did my driver side actuator this weekend. Today I look like I was in a fight with a cat my arms are so bruised, scratched and beat up. I invented new swears because quite frankly the old ones didn't work well enough.

    A few things I will add. Just get the one screw you can see out and then break the actuator off. It saves time and hassle.

    Get a set of tools like these:

    I used the thing in the middle with a set of long nose locking pliers:

    Clamped onto the flat part that helps you to manipulate it. I taped the screw to the socket (blue painters tape) and used a small electric screwdriver to put them in. Even the hidden one wasn't that hard. My major difficulty was getting the module back into the right place.

    Anyway, thought this might help someone else.
    GlassTop09, DieHarder and golkhl like this.
  14. Alan Russell

    Alan Russell Junior Member

    Here is what my tool looked like while using it:

    DieHarder and Dino Dino Bambino like this.
  15. GlassTop09

    GlassTop09 Senior Member

    Thanks for posting this Dino as it is now my turn to change these out.........just had the same scenario happen yesterday w\ my actuators as you had w\ yours.

    Ordered both MC YH1865, YH1869 & 1-YH1870 actuators (Rock Auto only had 1 YH1870 in stock so will be picking up the 2nd 1 once stock is refilled).
  16. GlassTop09

    GlassTop09 Senior Member

    Thanks for showing these pictures! I bought a full similar set off Amazon & these do make changing these blend door actuators out a hella lot easier.

  17. Rubyred54

    Rubyred54 Junior Member

    Does anyone know if the actuators are the same and/or in the same locations in the 10-14 S197s are they are in the 05-09 S197s? Think that my blend actuator is on the fritz. Refrigerant is OK, air blows cool (about 10 degrees below ambient), but not cold. Any help would be appreciated (live in Florida - it’s hot!!!!).
  18. Jack F

    Jack F Member

    The 10-14 HVAC plenum is different from the earlier S197s, so yes the actuators are in different locations.
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.