[mavryk1971]

Just purchased a used 1998 ML320 last week. Cannot get the heat to turn to cool or cold, just full on heat. By searching forums here disovered it is related to blender door issue. Removed dash, radio, etc to gain acces to the door. With the ignition on the blender motor turns to close door regardless of position of heater control. If I manually push the linkage to open the door and then release it, the motor returns it to the closed/heat position. I am guessing that something in the control is bad and therefore not sending proper signal to motor. How may I test to confirm this?
Also found a plug with red wire and brown wire that originates from the main cabin wiring harness in the area behind the radio that was just dangling and not connected. I cannot locate where this plug might need to go. It appears it was connected at one time. Wondering if this might be related to the heater issue?

Thanks

 

[mavryk1971]

Forgot to mention that I already performed the test of the temp sensor with a small piece of paper and it stayed in place on the tube.

 

[mavryk1971]

Found a wiring diagram and I believe the wire that was unattached is supposed to go to the A/C compressor. Can anyone confirm this?

 

[boardboy330]

I am experiencing the same issue that I hope to resolve soon.

 

[43sqd]

Whenever you are able to manually move the lever, that means that the lever is broken or one of the gears in the Blend Door Motor is broken.

Replace the Blend Door Motor, 163 820 01 08. When you replace it, the motor must be be bolted down and then the elec. conn. connected. Do not hold the motor in your hand and attach the connector to see if it works.

 

[boardboy330]

When you replace it, the motor must be be bolted down and then the elec. conn. connected. Do not hold the motor in your hand and attach the connector to see if it works.

I imagine when I hear the answer I will realize how stupid the question is, but why?

 

[43sqd]

Because the only way for the stud to rotate in either direction is if the motor driven worm gear turns.

 

[RJV]

Because the only way for the stud to rotate in either direction is if the motor driven worm gear turns.

Jim, whilst my dash is apart and I have clear access to the blend door actuator, is it possible/advisable to disassemble the actuator to check the condition of the gear teeth and to relubricate? I don't have any clicking or other issues with the actuator. Seeing the photo above I wondered whether the actuator could be opened non-destructively.

 

[boardboy330]

Because the only way for the stud to rotate in either direction is if the motor driven worm gear turns.

Yup, figured it was a stupid question. I need to check mine so at least I'll know.

 

[mlfun]

Just purchased a used 1998 ML320 last week. ... If I manually push the linkage to open the door and then release it, the motor returns it to the closed/heat position. I am guessing that something in the control is bad and therefore not sending proper signal to motor. How may I test to confirm this?

Thanks

http://www.benzworld.org/forums/w163-m-class/1550441-ml320-air-blend-motor-i-need-2.html#post4723930

 

[43sqd]

Jim, whilst my dash is apart and I have clear access to the blend door actuator, is it possible/advisable to disassemble the actuator to check the condition of the gear teeth and to relubricate? I don't have any clicking or other issues with the actuator. Seeing the photo above I wondered whether the actuator could be opened non-destructively.

Yes Rob you can open it, but as you do, hold the lower portion of the stud when separating the two halves.

The position of the ORANGE gear relative to the largest gear is the keystone to the entire setup , so do not remove any gear, grease it as is and reassemble.

 

[Neo7]

Has anyone investigated alternatives to the A 163 820 01 08 blender motor?

The ACDelco one is pretty much identical at half the price.... Amazon.com: ACDelco 15-72507 GM Original Equipment Temperature Valve Actuator: [email protected]@[email protected]@http://ecx.images-amazon.com/images/I/[email protected]@[email protected]@41RJEQIv9WL

I understand there many be electrical and mechanical differences inside but still worthy of invetigation. :laugh


All the best
Neo