So, most of you reading this are dealing with the most anemic heat (currently, it will be ac here in a few months) of any vehicle you own. Clut less threads talk about replacing the blower motor, checking all your flaps, cleaning brushes, possibly upgrading to a f 250 or 350 blower motor, ect ect ect.
My truck has a cracked block, it's been sealed, brazed, jb welded, stop leaked, it goes on an on, long story short, I dropped a 160 degree tstat in so I can reduce cooling system load as much as possible, cue clarksville tn winter, we only see single digits a few times, but it still sucks.
After going through and checking everything, I realized I was just spoiled by my lexus, it will melt your face off, the truck, not so much.

And to the meat and potatoes...

I bought this

SMAKN® DC Converter Module power adaptor Regulator 12V(8-16V) Step up to 18V 15A 270W https://www.amazon.com/dp/B00VRAZYN0/ref=cm_sw_r_sms_awd_9q4RwbZFMARW3

The wiring, at least for me, coming from truck to blower motor, orange wire (ground), black with what appears to be a red (could be orange) stripe, power, and they switch at the plug going to fan, orange becomes power, black ground.

Bottom of the step up inverter is clearly marked, 12v in + and - (the go to the trucks harness) 18v out + and - (these go to the fan).
Everything just got a bump up in airspeed, low you can feel, 3 feels like 4 used to, and 4 actually moves air for once.

Before all you electrical engineers go getting all crazy on me, I know I'm changing the load and this that and the other. The proper way to wire this would be with a dedicated power and ground relay that is on switched power, allowing for full demand of 18v power to be created. The resistor shouldn't care if it's seeing 18v or 12v so the blower motor resistor would be fine. And I know I'm spinning the blower faster than it was designed to spin, I was just giving an option to those who may want to wire it up on a switch for use only for short periods of time, or maybe only at full speed to limit some of the resistor heating.

***edit***
Giving the inverted an un regulated ground on the 12v side let's it pull as much current as the 30 amp fuse allows, proper wiring should be, blackc with orange/red stripe 12v in on inverter, ground to chasis 12v out (I used the engine ground right above blower assembly) 18v out to blower motor supply (orange wire) and a jumper installed between blower outlet (black) and truck harness blower ground going through truck blower resistor (orange). 18v ground on inverter is unused.

Could be s implied by cutting power wire on either blower side (orange) or harness side (black with red/orange), and wiring 12v in to truck, 18v out to blower, and adding ground to 12v ground somewhere on truck.
Giving the inverter

 

I'm not sure how this is a "fix" at all? The stock blower motor running at the factory ~14v can more than heat a crew-cab F-250.

If you don't have good heat, something is wrong, simple as that. Running the blower motor at 18v is just going to wear the motor out faster, and put more strain on the Ford blower resistors which are already infamous for burning out. The resistors with 18v going through them will have a much higher power load on them, and reject a lot more heat and run hotter.

 

+1 I have and have had many a Ford truck and the heaters have always been more than enough in stock configuration to get the job done.

Here where I live it can and will get to -20 deg or lower at times and never had a problem getting enough heat.

You got a leaky motor one suffering from cooling issues, cooling issues equate to heat issues.

A 160deg thermostat, that is low even by 70ies standards. Seventies models called for a 180deg IIRC. I know that's what I ran and had heat that drive ya out of the cab in a hurry if didn't turn it down. IIRC "high output heat" was their claim to fame at the time. (went as far as said so right on the dash? IIRC?), no longer make that claim but no difference in the system in this series truck from those older models.

These trucks call for a 192deg thermostat.

You have heat ducting/diverter issues something limiting air flow/misdirecting it and on top of that cooling system issues.
An attempt to overcome those issues with higher fan speed wasn't the best choice and isn't the answer for a system that "as designed", is more than adequate to the task. Addressing those two issues would have been time/effort better spent IMO.

 

Interesting way to solve your trouble. Not a fix though, that is a band-aid for the real problems. When in good condition the heat in these trucks will get plenty hot. Also... that little device you have there ain't an inverter, it's a DC-DC boost converter.

 

I have a 1996 Ford F150. For about a year, the blower would only work on 1 speed. A few days ago the blower stopped working. When I'm driving I can feel the cool air coming from the vents, but the blower stopped working. Do I need to change the blower resistor?

 

Yes.. and likely the connector and 6-8" of the wiring harness as well, these things corrode into a solid mass and usually don't come apart. I have replaced these parts on EVERY SINGLE FORD TRUCK I have ever owned. My current truck.. the 06 E250 uses the same resistor pack and guess what.. it currently only works on the top 2 speeds.