With all the experience here, can anyone help me with this? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Streetglide2015 · 12-08-2018, 11:58 PM

I just bought a beautiful 64 C10 short-bed, which has been basically restored. It has Thrift Air heat, but the fuses keep blowing. Each time I replace the blown fuse, I switch on the fan (all speeds), it runs for about 20 seconds, and fuse blows again.
Since the switch, and the fan motor seem to operate, could this be a resistor problem? Is there a fan motor relay also?
I located the resistor, but cannot seem to determine the location of a relay.
Any ideas on what else may be the cause?

Thanks!

Streetglide2015 · 12-09-2018, 12:42 PM

I just bought a beautiful 64 C10 short-bed, which has been basically restored. It has Thrift Air heat, but the fuses keep blowing. Each time I replace the blown fuse, I switch on the fan (all speeds), it runs for about 20 seconds, and fuse blows again.
Since the switch, and the fan motor seem to operate, could this be a resistor problem? Is there a fan motor relay also?
I located the resistor, but cannot seem to determine the location of a relay.
Any ideas on what else may be the cause?

Thanks!

kazoocruiser · 12-09-2018, 12:53 PM

Maybe the brushes in the fan itself have worn out. If it is binding because of it, that would cause excessive current draw.

cryowagon · 12-09-2018, 02:08 PM

There is no relay. Power goes from the fuse to the switch, from the switch to the resistor, then from the resistor to the blower motor. On the highest speed, I believe the resistor is bypassed, so if the fuse is blowing on high, its probably not the resistor. I think that if there is a short in the switch, it would blow the fuse immediately.

Streetglide2015 · 12-09-2018, 08:16 PM

Quote:

Originally Posted by cryowagon

There is no relay. Power goes from the fuse to the switch, from the switch to the resistor, then from the resistor to the blower motor. On the highest speed, I believe the resistor is bypassed, so if the fuse is blowing on high, its probably not the resistor. I think that if there is a short in the switch, it would blow the fuse immediately.

That sound very possible. Each time I switched on the fan (after replacing a fuse) I twisted it right to high. As I said, it runs for about 10-20 seconds, then blows fuse. It seems like a pretty simple problem to diagnose, and a new resistor is cheap enough to give it a try.
Thanks!

kazoocruiser · 12-09-2018, 11:33 PM

Quote:

Originally Posted by Streetglide2015

That sound very possible. Each time I switched on the fan (after replacing a fuse) I twisted it right to high. As I said, it runs for about 10-20 seconds, then blows fuse. It seems like a pretty simple problem to diagnose, and a new resistor is cheap enough to give it a try.
Thanks!

If you have access to a multimeter, you can test the resistor pack to make sure it is bad before you buy a new one.

You can use a multimeter to test the amperage draw across a load. If your entire circuit is rated at 15 amps, and then the fuse blows, you have an over-amp condition.

I think someone already indicated there are no resisters in series when the fan blower is on high.

You could unplug the fan, and if a fuse blows then, it's the wiring.
If it doesn't blow then, I think it would eliminate everything but the fan.

You might actually remove the fan and do an inspection to see if the blower wheel is able to rotate freely. Maybe it needs to be checked for free rotation and lubrication.

goofy063 · 12-10-2018, 01:39 PM

It'll be the fan motor

shp4man · 12-10-2018, 03:03 PM

My truck's fan motor was seized when I got it. Took it out, drilled a tiny hole in the lower bearing, lubed it up with a grease injector, 2 years and still working.

Streetglide2015 · 12-10-2018, 06:33 PM

Thanks much for all the assistance!

**PGSigns** · 12-11-2018, 07:27 AM

Unplug the fan and see if it still blows the fuse. If it does its in the wiring to the fan and you can look for shorts to ground in that wiring. If the fuse does not blow pull the fan and bench test it. Also what amperage fuse are you putting in it?
Jimmy

**The Rocknrod** · 12-11-2018, 08:57 AM

Maybe the answer is here?: http://67-72chevytrucks.com/vboard/s...d.php?t=776911

WhippinSaw · 12-12-2018, 12:30 PM

My 63 had the blower wire short where it goes through the firewall.
Didn't blow a fuse but started a fire and filled the cab with smoke.

mikie 1954 · 12-12-2018, 02:53 PM

Make sure you have the right size fuse in it to. When I bought mine someone had put the wrong fuse in it and it kept blowing until someone on here told me to check it. Good luck

chevy_mike · 12-13-2018, 11:47 AM

You had two different posts about the exact same thing. I have merged these two threads into one.

12-08-2018, 11:58 PM	#1
Streetglide2015 Registered User Join Date: Dec 2018 Location: Algonquin, IL Posts: 28	64 C10 with heater blower glitches. Advice? I just bought a beautiful 64 C10 short-bed, which has been basically restored. It has Thrift Air heat, but the fuses keep blowing. Each time I replace the blown fuse, I switch on the fan (all speeds), it runs for about 20 seconds, and fuse blows again. Since the switch, and the fan motor seem to operate, could this be a resistor problem? Is there a fan motor relay also? I located the resistor, but cannot seem to determine the location of a relay. Any ideas on what else may be the cause? Thanks!

12-09-2018, 12:42 PM	#2
Streetglide2015 Registered User Join Date: Dec 2018 Location: Algonquin, IL Posts: 28	With all the experience here, can anyone help me with this? I just bought a beautiful 64 C10 short-bed, which has been basically restored. It has Thrift Air heat, but the fuses keep blowing. Each time I replace the blown fuse, I switch on the fan (all speeds), it runs for about 20 seconds, and fuse blows again. Since the switch, and the fan motor seem to operate, could this be a resistor problem? Is there a fan motor relay also? I located the resistor, but cannot seem to determine the location of a relay. Any ideas on what else may be the cause? Thanks!

12-09-2018, 12:53 PM	#3
kazoocruiser Registered User Join Date: Aug 2018 Location: Bronx, NY Posts: 215	Re: With all the experience here, can anyone help me with this? Maybe the brushes in the fan itself have worn out. If it is binding because of it, that would cause excessive current draw.

12-09-2018, 02:08 PM	#4
cryowagon Registered User Join Date: Apr 2004 Location: Piedmont, OK Posts: 44	Re: With all the experience here, can anyone help me with this? There is no relay. Power goes from the fuse to the switch, from the switch to the resistor, then from the resistor to the blower motor. On the highest speed, I believe the resistor is bypassed, so if the fuse is blowing on high, its probably not the resistor. I think that if there is a short in the switch, it would blow the fuse immediately.

12-10-2018, 01:39 PM	#7
goofy063 Registered User Join Date: May 2017 Location: salem ky Posts: 13	Re: With all the experience here, can anyone help me with this? It'll be the fan motor

12-10-2018, 03:03 PM	#8
shp4man Registered User Join Date: Oct 2016 Location: San Diego, CA Posts: 557	Re: With all the experience here, can anyone help me with this? My truck's fan motor was seized when I got it. Took it out, drilled a tiny hole in the lower bearing, lubed it up with a grease injector, 2 years and still working. __________________ Everybody has to believe in something. I believe I'll have another beer.

12-10-2018, 06:33 PM	#9
Streetglide2015 Registered User Join Date: Dec 2018 Location: Algonquin, IL Posts: 28	Re: With all the experience here, can anyone help me with this? Thanks much for all the assistance!

12-11-2018, 07:27 AM	#10
PGSigns Senior Member Join Date: Jan 2011 Location: Hayes Va Posts: 4,569	Re: 64 C10 with heater blower glitches. Advice? Unplug the fan and see if it still blows the fuse. If it does its in the wiring to the fan and you can look for shorts to ground in that wiring. If the fuse does not blow pull the fan and bench test it. Also what amperage fuse are you putting in it? Jimmy __________________ 60 to 66 Chevy and GMC window decals http://67-72chevytrucks.com/vboard/s...d.php?t=661131 Good friends, good food and a hotrod what else do you need? 1966 BBW long fleet Daily driver 1965 BBW short fleet Sold and going to a good home 1965 Suburban 2003 3500 Duramax 2005 Ultra Classic

12-11-2018, 08:57 AM	#11
The Rocknrod Moderator Join Date: Aug 2011 Location: China Spring, TX Posts: 7,280	Re: 64 C10 with heater blower glitches. Advice? Maybe the answer is here?: http://67-72chevytrucks.com/vboard/s...d.php?t=776911 __________________ Master Chief, US Navy, Retired 1964 C10 Step-side Short Bed - In Progress 2009 2500HD Duramax LTZ 1948 GMC Panel 1956 Big Window Stepside 1953 5 Window Chevy Stepside 1932 Coupe New Seat Foam for Bench Seats?

12-12-2018, 12:30 PM	#12
WhippinSaw Registered User Join Date: Aug 2012 Location: Lisle Illinois Posts: 602	Re: With all the experience here, can anyone help me with this? My 63 had the blower wire short where it goes through the firewall. Didn't blow a fuse but started a fire and filled the cab with smoke. __________________ 1963 Fleet Side cab, Converted Fleet Side Barden bumper, Step Side in the middle.

12-12-2018, 02:53 PM	#13
mikie 1954 Registered User Join Date: May 2009 Location: caliente ca. Posts: 297	Re: With all the experience here, can anyone help me with this? Make sure you have the right size fuse in it to. When I bought mine someone had put the wrong fuse in it and it kept blowing until someone on here told me to check it. Good luck

12-13-2018, 11:47 AM	#14
chevy_mike Never Ending Projects Join Date: Jul 2006 Location: San Diego, CA Posts: 3,836	Re: With all the experience here, can anyone help me with this? You had two different posts about the exact same thing. I have merged these two threads into one. __________________ . 1965 C10 Panel, Tiki Express http://www.67-72chevytrucks.com/vboa...d.php?t=506580 SOLD 1968 Chevy C10, Long, Fleetside, Hot Rod Hauler http://67-72chevytrucks.com/vboard/s...d.php?t=313233 SOLD 1965 Chevy C10, Long, Fleetside, Hot Rod C10 http://67-72chevytrucks.com/vboard/s...d.php?t=415702 SOLD We were given two ears and one mouth for a reason... listen twice as much and speak half as often...

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