Blend Door Actuator How to check
 

Ok I have a belnd door issue. I have read many threads. I proceeded to replace my blend door however when I took out the actuator and turned the control know nothing happened. So now I believe it is either the actuator or the control knob. I tried to check resistance/current but probably didnt do it right. But to me there is no power to the contol knob. Everything else works. :-banghead Fan and switching from defrost to floor no issues. Any one have any ideas. Many thanks.

Larry

So check the actuator with jumper wires.See if it works

Thank you for your reply. Im am not good with electrical. However seems like a good idea. Ther are 5 wires that go into the connector. Would I just try the positive (red) and negative (black)?

Sounds like a plan. If the red one does nothing run it to the other terminals with the ground hooked up still

Just connect actuator to his original harness and see is it turn. Don't forget check knob. In my case knob was cracked and just spin around his metal rod.

There is no significant power at the three wire plug at the control knob, the three wires are directly wired to a potentiometer. In the five wire plug on the actuator there is a ground and twelve volts. To test knob, use a multimeter to check for changes in resistance from the middle to the outsides, and for a constant resistance on the outsides. Use a voltmeter to check for 12 volts at the actuator plug, hooking to the two wires that are diff colors than the three that go to the control knob. If you have 0 volts with key in run position, you prolly have blown fuse. The knob resistance can be checked regardless of key position. If turning the knob varies the resistance, and you have twelve volts in run, then your actuator is probably bad. iF turning the knob yields no change in resistance, than the knob is slipping and not turning the shaft it sits on.

Thanks for proceedure noonespecialer. I will give that a try. I will post my finding but it will be this weekend before I have an opportunity to check. Thanks again for the great ideas.

Blend door actuator problem- power to door?
 

I have a similiar problem to dunerookie on my 1999 Econoline E350. The blend door actuator will work for while and then die. Sometimes there appears to be power to the actuator, and other times not. I'm thinking there is a short somewhere between fuse #13 and the actuator, but I can't find it. I'm also wondering why a short would blow out the actuator instead of just stopping it from functioning during the time that it had no power.

The fuse itself is ok. I've already replaced the heater control switch.

Any assistance would be much appreciated.

if the actuator works part of the time, i would guess the gear box has stripped teeth or rod broken. You will need to remove and check to power to see if power comes and goes, or the gear box is stripped.

2006 f250
 

I have a similar problem think it's my climate unit temperature switch/ I don't see any movement on the heatercore control valve under the hood
I tested the plug to the blend door actuator to the best of my ability and only read 2v so i turned the truck on and read 5v and continuity between a few pins don't know what to think any suggestions really appreciate

I have a 2011 F-150 when I turn on the A/C it gets cold on the passenger side and in the rear back seat area. But still blows heat out the drivers side . I do have dual heat. Help

This worked great for me. Just a clarification for those who are not well versed in the electrical stuff.
To verify the temp control knob is working, unplug the actuator,
Identify the 3 colored wires grouped together (2 similar and 1 different) coming out of the back of the knob
and test resistance between one of the similar colors and the single color.
Maintaining contact with these leads, and the key on, turn the knob back and forth. THe resistance should change substantially.
Now check the other similar color against the same single color.... should get same result basically
Now check the voltage at the other two pins we have not yet touched.
With key on it should be 12V.

By my estimation, if you have all 3 of these, and then you plug in the actuator, and it does not turn, the actuator must be bad.

2003 F-150 Lariat with 4spd MT (w/OD)
I am having much the same issue. There is no power getting to the blend door actuator itself. I bought a new actuator and when connected NOTHING happens. The system does switch between different locations of output. The blend door actuator does not move at all when changing temperature output level. Have checked ALL fuses throughout the truck and can not find any bad ones (on a positive note I found out what fuse controls my Reverse lights now those work). Also, the accessory outlet (next to the cigarette lighter female plug) does not work but the cigarette lighter does) does not work.

@TrafficProsCincy I think it sounds like you may have a faulty temperature control dial. You should be able to measure the resistance of the dial itself if you remove the trim and pull off the control assembly and remove the temperature control knob (unless your truck has the EATC module)

I wish I could remember the pins to check resistance across, but you should be able to check the resistance across the pins on the back and rotate the knob to see if you can see a resistance change. Resistance should varies between 300 ohms and 3000 ohms.

Incidentally, the shaft on the actuator only turns thru an angle < 90 degrees. For example, at full warm (~3000 ohms) and rotating over to full cool the resistance will go from ~3000 ohms to ~300 ohms, i.e., it decreases linerally during the rotation.