HVAC blower not working

[Redwolf1155]

2019 Ram 1500 Classic. My hvac blower has quit working. Ive replaced the blower, tried a second new blower, checked the underhood fuse, and swapped with a known good underhood relay and the blower will not run. The blower has the 3 wire connector plugged in to it. I have 12v on the 2 large wires and also 12 volts on the small middle wire to ground that varies from 9 to 12 volts when changing the fan speed. The truck has the touchscreen/knob fan controls with dual zone temp. Im not sure what else to check. I assume it could be something to do with the signal wire but i have no idea.

 

[04fxdwgi]

Have you checked the blower resistor?

Location and Identification

• • Location: Under the passenger-side dashboard, near the blower motor housing.
  • OEM Part Number: Often referenced as Mopar part 68429642AA (varies by exact build date and whether you have manual or automatic temperature control). [1, 2]

Common Failure Symptoms

• • High speed only: The fan works on the highest setting but fails on lower speeds.
  • No airflow: Total loss of power to the blower fan.
  • Intermittent operation: Fan cuts out randomly due to an overheating or failing electrical connection. [1, 2, 3, 4]

Replacement Steps

• • Disconnect power: Unplug the negative battery cable or pull the designated blower fuse/relay to prevent electrical shorts.
  • Remove trim: Remove any lower dash panel or footwell cover on the passenger side to gain clear sight of the blower motor area.
  • Unplug harness: Squeeze the release tab on the electrical connector and pull it straight off the resistor.
  • Unscrew fasteners: Remove the screws (typically Phillips head) securing the resistor to the HVAC housing.
  • Swap and inspect: Pull the old unit out, check the cavity for debris or moisture, and slide the new resistor into place.
  • Reassemble: Secure the screws, plug the electrical connector back in, and test all fan speeds before putting panels back.

 

[Mpgrimm2]

You may have a bad/missing ground at one of the larger pins (pin 1 ) if you have 12v on both sides?

As the voltage control signal (pin 2) changes, the fan should speed up.