HVAC fan not working

[onebad70stang]

I am working on my father in law's 2009 mustang v6 5sp that over the past few years I have been really frustrated with the blend door actuators and resistors and fan. I have probably replaced 10 to 12 actuators- real number - 3 or so resistors and 1 fan. This system has been ridiculously troublesome. The latest- as of a few weeks ago- is the upper passenger blend door actuator ( clicking like crazy and I have one coming) and the fan. The fan will not blow on any speed. When check the voltage at the pigtail unplugged, it is 11.3v but as soon as I plug it in the voltage drops down to 0. I can run a wire from the battery and it runs just fine, I even used a 9v battery out of my garage door key pad and it ran smoothly. But if I plug in the pigtail 0 volts, and As soon as I unplugged the pigtail the voltage comes back. I replaced the resistor pigtail and ran an extra ground for it. I tried another fan - I have the old one- and it did the same. I also tried another resistor (3 - new, old, really old) all the same thing - voltage there until you plug it in. Any ideas???

 

[heavyburnin]

Did you buy motor craft branded ones? Also on the passenger side the top and bottom look the same but share a different part number. I used a cheap Amazon one before and it lasted a month. I switched to motor craft and have been fine for months. Also make sure they’re installed correctly, check the back of the ac buttons and make sure your two connectors are plugged in and seated correctly.

 

[86GT351]

Did you buy motor craft branded ones? Also on the passenger side the top and bottom look the same but share a different part number. I used a cheap Amazon one before and it lasted a month. I switched to motor craft and have been fine for months. Also make sure they’re installed correctly, check the back of the ac buttons and make sure your two connectors are plugged in and seated correctly.

Correct. What brand products are you using? There is a difference.

 

[onebad70stang]

For the blend door we are using either Dorman or duralast or store brand. The fan issue- one is factory and the other is rock auto- not sure of the brand - and they both are the same. Would a bad fan pigtail cause the fan issue????