Hey guys I am completely stumped. My blower stopped working all speeds so I grabbed my multimeter and started tracing power and checking fuses. Everything looked good all the way to the blower motor. At the plug I have 12.5 volts from one side of the plug to the other and from the hot side to body ground. I thoight the motor must be bad but when I replaced it got nothing. Hooked my new and old motor up to a battery and they run strong so I returned the new motor. If I measure at the plug I have 12.5v, when I plug it in I get no motion. Please help!

 

For specific advice, you MUST EXPLICITLY IDENTIFY YOUR VEHICLE as well as which climate control system is installed.

With the motor's connector plugged in, do you have power on BOTH or only one of the wires? Back-probe the connector as needed.

If you have power on both, you have an open ground circuit. If a manual system, make sure the speed switch is in HIGH speed for voltage tests.

If you have power on the supply side but nothing on the low side, assuming no other circuit faults, the blower motor is open.

 

Hi there sorry for not supplying enough information. I have a 2011 Ford F150 Lariat Supercrew. On my controls I can place them in auto and it will turn on and off and adjust fan speed to regulate temperature or I can just manually control the fan speeds and zones. As of yesterday, all at once, the blower does not run under any setting or speed auto or manual. All fuses are checked good. When I unplug the fan motor (2 wires) and test voltage at the plug I get 12.5v DC with the fan speed set to maximum. If I turn the fan off that voltage goes to zero. Those measurements are from prong to prong and from 1 side of the plug to ground. When I take my blower motor (removed from truck) and put 12v from a battery directly to it it runs no problem. When I plug it in to the plug under my dash (the one that I measure 12.5 volts on) I get nothing. So basicly my meter says I am getting power but my motor which tests good doesnt turn.

 

Do the voltage check EXACTLY as I recommended.

 

I just replaced the blower resistor on my '12 Lariat Supercrew this evening. Did not fix it. I had read on another forum that this could be the issue.

Where exactly is the fan located so I can start working on it next?

 

We had a 2006 XLT that did this, it ended up being a bad ground.
If you do the Test like projectSHO89 says and have voltage on both side and since you know the blower is good you should look for a broken wire or loose connection on an under-dash body ground.
Truthfully you should look at the wiring diagram since some controls could be on the negative side but if you want it to work running a jumper wire from the negative side to anything grounded should work also so you have a fan.