Strange blower motor problem
Thread Starter
|
Senior User
Joined: Feb 2005
Posts: 140
Likes: 0
Strange blower motor problem
First specifics: 72 F100 Ranger XLT, Factory AC
Problem - Blower motor not running.
What I've checked - I've tested the motor by running 12 volts straight from the battery to the orange wire to the blower motor. MOTOR WORKS.
I've checked power from the switch to the resistor. The plug that goes into the resistor has power at one of the prongs when switched at the control switch which means the switch is working and the power is getting to the resistor. With the plug connected to the resistor, there is power at the prong that goes to the blower motor (where the orange wire connects) 12 volts when the orange wire is NOT connected. when I do connect the orange wire to the prong there shows NO power. I'm thinking it is the resistor but there seems to be no damage to the coiled wires or anything else on the resistor. I'm stumped at this point, can anyone help? Thanks in advance.
Problem - Blower motor not running.
What I've checked - I've tested the motor by running 12 volts straight from the battery to the orange wire to the blower motor. MOTOR WORKS.
I've checked power from the switch to the resistor. The plug that goes into the resistor has power at one of the prongs when switched at the control switch which means the switch is working and the power is getting to the resistor. With the plug connected to the resistor, there is power at the prong that goes to the blower motor (where the orange wire connects) 12 volts when the orange wire is NOT connected. when I do connect the orange wire to the prong there shows NO power. I'm thinking it is the resistor but there seems to be no damage to the coiled wires or anything else on the resistor. I'm stumped at this point, can anyone help? Thanks in advance.
Lead Driver
Joined: Apr 2011
Posts: 6,399
Likes: 40
From: El Dorado, Arkansas
Bypass the resistor by disconnecting both wire leads from the blower motor. Ground one wire and (momentarily) put +12 volts on the other motor lead.
If the blower motor doesn't turn over either the bearings are bad or the motor is shot. If the blower motor does turn over, the problem is further up stream --resistor, wiring, etc.
If the blower motor doesn't turn over either the bearings are bad or the motor is shot. If the blower motor does turn over, the problem is further up stream --resistor, wiring, etc.
Thread Starter
|
Senior User
Joined: Feb 2005
Posts: 140
Likes: 0
Bypass the resistor by disconnecting both wire leads from the blower motor. Ground one wire and (momentarily) put +12 volts on the other motor lead.
If the blower motor doesn't turn over either the bearings are bad or the motor is shot. If the blower motor does turn over, the problem is further up stream --resistor, wiring, etc.
If the blower motor doesn't turn over either the bearings are bad or the motor is shot. If the blower motor does turn over, the problem is further up stream --resistor, wiring, etc.
Tuned
Joined: May 2010
Posts: 281
Likes: 9
From: Benton City, Wa
If you have a multimeter, switch it to ohms and measure the resistance from tab to tab on the resistor with no power supplied to the resistor. If the meter reads zero or close to it, then the resistor should be good. Wiggle the tabs around when measuring because there 'may' be a hairline crack you can't see. If the meter reads infinite, then the resistor is bad someplace. Some meters have a tone making them easier to use when checking continuity. Use alligator clips (roach clip for us old guys) if possible. Only other thing that I can see is the orange wire connector 'may' be bad.
I'm guessing it's like this part or something similar.
Dan
I'm guessing it's like this part or something similar.
Dan
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 784
From: Simi Valley, CA
C8TZ-19706-B .. Blower Motor Resistor-Use with factory installed integral A/C / Obsolete
1968/72 F100/350 / 1969/70 E100/300 with single evaporator.
NOS PARTS LTD in Waxahachie TX has 1 = 972-937-2201.
1968/72 F100/350 / 1969/70 E100/300 with single evaporator.
NOS PARTS LTD in Waxahachie TX has 1 = 972-937-2201.
Thread Starter
|
Senior User
Joined: Feb 2005
Posts: 140
Likes: 0
One problem fixed, now another. I found a wire that the PO must have added. The light for the AC controls were wired to the brown wire that feeds power to the HVAC system. As soon as I clipped it, the blower started working. I let it run for a few minutes while I hooked up the gauges to see if there was any pressure in the system and it blew the fuse. I replaced it and a few moments later it blew again. The fuse was HOT. I THINK the prongs that hold on to the ends of the barrel fuse is very loose causing it to heat up. I'll try to sand them down and bend them to give a better grip on the fuse and report back.
Trending Topics
Logistics Pro
Joined: Aug 2015
Posts: 4,093
Likes: 14
From: Lind, WA- Eastern WA
If that resistor is good then the motor is going bad. If it blows the fuse it sounds like the motor is struggling to keep going, so it is drawing more Amps. The bearings may be bad or the windings- I don't know if that motor has brushes or not. The resistor gives you the ability for variable speeds, that's it's only function in life.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Thread
Thread Starter
Forum
Replies
Last Post
DKW 86
1973 - 1979 F-100 & Larger F-Series Trucks
6
Oct 5, 2010 03:02 PM