On my 2014 F150 The air heat blower quit working on it. I got to looking and saw this might be the Blower Resistor o I replaced it... There was no air at all... I connected it screwed it on and now it ONLY BLOWS ON HIGH.. AIR, it will not cut off it stays on blowing on High... So I did take it off went to where I got will swap for another on just in case.. Anybody got any IDEALS on what this might be..
David
Lebanon Tennessee

 

The high speed setting is the only one which the blower motor current does not flow through the resistor. I would look carefully at crimped connections associated with the voltage dividing resistor assy. You can check each leg in and out of the resistor with a volt meter and ground.

 

While you are at it,, good idea to confirm power is coming out of the blower motor switch at those slower speed settings.

Because not everyone has test equipment , if you don't have a voltmeter a simple test light will confirm if power is getting to the resistor and it is a good investment inexpensive and easy to use.

 

So one day the blower just STOPPED KA PUT.. i got to looking on You Tube and saw about the Resistor so I found where it was and how to replace it.... I got to NAPA got one put it on and it runs stays on HIGH... I put it on NOW I go to the STEALER I mean Dealer.. He says cant get you in till a month... He tells me they always replace Resistor and Blower at the same time... they will do that in a month take if from there... HMmm so Im thinking well maybe its a bad defalt Resistor what the heck.. I go back to my Napa buds and say dealer said might be bad Resistors.. So they got to order me another fine I don't want to get another made same time is one I got... So I got back Sat pick it up after church I got chores to do mowing bushhoging around the place get it all done.. 3pm OK lets put in new Resistor so I do hook it up tighten up screws start up truck......VA BOOM SH ZAMMmmm it WORKS fine like it is pose to makes me so happy guys Im 70 years old getting to old to be piddleing with my truck..... BUT I"M GRINNING EAR TO EAR!!!!

 

i GOT it replaced and it worked fine for 3 months then it stopped AGAIN??? Any Ideals

 

The blower resistor works by varying the grounding function for the blower motor to achieve speed levels. The Thermal Protector on the resistor if it goes bad will default the fan speed to HIGH.. If a resistor is in question, you can either check the thermal protector with a meter for an open, or as a 'test only' you can bridge the TP with a test wire and all the speeds should then be available.
If still no full range of functions, I'd be suspect of the panel fan selector.

 

There might be a little more to this saga.

What you might consider , if possible and you have the means to do it , measure the current draw of the blower motor itself. If it is excessive , it will continue to ruin every resistor you install eventually.
If you find it is excessive , blower motor replacement would be required.

 

Guys Im a way older man not as swift I used to be... This one I GOT now cost me $125 at parts store.. I found EBAY $22 I may have to get these. we will see

 

You might check around and see what a good shop would charge to do this for you. It is not difficult if you have the equip and could take about 10 minutes.

Then at least you would know where you stand and hopefully repair the cause , once.

 

Hanky makes a good point on the motor, but being the resistor lasted 3 months it may/may not be the motor itself. Certainly a possibility. When it was working on all the speed ranges, how did the blower motor sound? A lot of times if the bushings lube dry out they will squeal, growl, vibrate etc as they time out, or due to conditions.
The Thermal Protector is cooled with air passing over the unit. If there's any collected debris, leaves etc, in the system intake, it can overheat the TP and it will fail again.
And again, if you suspect it's bad again, (prior to buying another or if no meter etc is available) use a test wire and 'bridge' each end of the TP's posts. Eliminating its protective function, will then return all the fan speeds. If not, then either the motor, or air restriction, or possibly an issue with fan speed control on the panel. I've seen the connector burn on the backside of the selector, but most often if the selector/connector has connection issues, a replacement resister wouldn't correct the issue..