1999 3/4 diesel

I have the blend door motor out, and I need to replace the adaptor to the door. I dont have the dash out (did that exercise already, and put it back in).

Do I pull straight down on the adaptor and then push the new one straight up in?

I replaced the motor when I had the dash and AC/heat unit out, but still same problem. Has to be the adaptor.

The motor moves each way when the temp control is moved.

Thanks

Mike in Tucson

 

Also, interesting difference between the old and new blend door motor

Old has 3 pins on its connector, and it moves over and stops at the full cold setting, and moves the other way and stops at the full hot setting, with small movements in-between when you move the temp control

The new has 4 pins on its connector, and it moves over and stops at the full cold setting, and moves the other way toward hot in increments when you adjust the temp setting. But, at about 3/4 way toward hot, it starts moving toward the full hot blend setting and never stops moving. The motor just keeps running, trying to get to the hottest blend setting.

Wiring harness that connects to the blend door motor only has 3 wires

???

Mike

 

The motor has a "built in" limiter. It doesn't actually know positions. It sees an amperage spike when the door stops and the motor knows to stop turning. I'm also guessing the motor is wrong. Have part numbers off old and new? I can run them to see if they are right.

 

I must have missed where you described the problem. I had a problem where the blend door stayed to the full cool side. I'm not sure why or what happened to cause that. It could have been a rushed installation when I put a new evaporator core in, but I was sure that was ok at the time.

Solution was to take a 1" spade bit, and carefully place a hole in the bottom of the case where the door was stuck. I then pried it loose. Certainly, damage could be an issue. However, the fix was cheap fast and very easy, with no bad effects at all.

Just be sure you know exactly where you are poking the hole, since there are things that hate having holes in there.

To cover the fix, I put a piece of black duct tape over the hole.

 

There are two problems.

1) There is an issue with the new blend door motor that I got from the dealership. It has 4 pins on the connector, where as the old part has 3 pins. The old part stops at each limit, without being connected to the blend door and responds to the temperature control. The new part stops at the cold limit, but does not stop at the hot limit, and responds to the temperature control.

The numbers off of each part are:
The old part number is:
AA 113800
2060
2828 B

The new part number is:
AA 113800
2610
1147 A

One of these parts might be the week and year it was made in, dont know.
Any help on this problem is appreciated.

The second problem, is that I believe the blend door motor coupling is cracked, which caused my initial probem of the blend door moving on its own, independent of the temp control.

I have the motor out, and I have a new coupling.

How do I get the coupling out from the bottom of the dash and replace it without removing the steering column, instrument panel, and heating/ac unit, like I did before?

Thanks

Mike

Also, anyone interested in going thru the whole procedure of removing the AC/Heat unit is welcome to ping me and I will give some insights and help on what not to do. Also, ALWAYS replace the heater core when you do this, its only $90 at Autozone, and it is well worth the trouble.

 

Also, its a Lucas part designed and made in Winona, MN. If I had a schematic of the new part, maybe I could short the extra pin to ground or something to get it to react like the old. Also, it moves much faster than the old part.

Mike

 

bigyoda, I used to work at the TRW (Lucas) plant that makes this stuff. While I did not work on the design of these I did do machine design engineering for assembly of this stuff. Since you have a 99 ( right?) it's past the 10 year mark so it would not surprise me in the slightest that the new part is a bit different. Whether you can take it apart or not depends on how careful you are about breaking it. Most of these are assembled using an automated ultrasonic welder. I think the material is ABS so you can easily glue them back together. There is probably a circuit board inside and it may not be possible to modify it. Some electrical eng. here might be able to come up with an electrical limiter so it doesn't overdrive it self as you noted. Maybe you can just put a small micro switch to limit travel if you can do some electrical work.

There were often changes to the circuit boards of these that required design changes in the assembly machine so even though it looks the same it may not be the same internally.

There are different spline drives on these too. I haven't had mine out so I don't know exactly which one is there. On some the splines are only different in position or clocking. You could not tell just by looking at an individual one.

I can't even begin to tell you how many actuators there are.

While it would be very, very unlikely that it was mis-packaged at assembly, it is possible that it may have been repackaged later and mixed up so you may indeed have the wrong one. No fault of the mfg.

 

I am not sure about the part number/motor issue. You would have to speak to the parts guys where you got the part.

As to the coupler, it should fall out of its position. Mine came out with the motor. If you have a set of picks, they should be able to get the coupler out.

 

I will try to pry out the coupler.

As far as the blend door actuator. I have both of them apart. The abs plastic assembly has four pry snaps, which if careful, the two halves come apart. The circuit boards are different, and the servo motor chips are different.

The new chip is an 8 pin device, with pin 4 of the connector connecting to it.

If you try to hold the actuator from moving while trying to go to the hot position, it wont stop, so there isnt a current limit to stop it, probably will snap the new coupler.

I believe that it stops when it sees a balance in the resistance coming from the temp control.

 

Old coupler is out, and it was cracked. new coupler is in, and old motor is in.

Still would like to use the new motor, if possible, but it would certainly crack the new coupler since it doesnt stop at the hot setting

 

That's exactly the problem that I discovered when I made the test machine for these.
The "powers" felt that the control **** position and as a result the actuator position was sufficient to prevent hard stopping and breaking the couplers.

When I questioned this I was told to

Why am I a frustrated engineer??? Oops (was) I'm retired now haha.