Heater Blower Tripping Breaker

[renovate7]

I tried using the heater for the first time this year. The blower comes on for a second or so and then the breaker trips. This was a new blower motor last year and doesn't have 2 hours on it. I tried a new breaker and got the same results. I took the squirrel cage off to reduce drag and it still trips the breaker. I also put the motor shaft in an electric drill and ran it for a bit at low RPM's to "loosen it up" and polish any crud off the armature. Still no go. A volt meter shows it getting 26.2 volts. It's a sealed motor and looks like a bear to try and get apart. Any ideas short of ordering another motor?

 

[Speddmon]

use a low ohm meter and make sure you're not grounded through the motor armature...the armature will be a very low resistance, but should not be zero!

Have you had anybody else turn it on for you to make sure it's even turning before the breaker trips? Possibly a brush problem (one of them hanging up), but I don't remember if you even have access to the brushes on these motors.

 

[m-35tom]

or you could put an amp meter in the circuit and see what is says.........

 

[renovate7]

Thanks for the quick reply. I stood on the drivers side running board while turning it on and could see the impeller turn. It comes up to full speed for a fraction of a second and then the breaker trips. It worked well last year. I have an old Fluke meter around here some where with a DC inductive pickup. If I can find it and remember how to use it I'm going to see how many amps it's pulling. The breaker has 9-115-5-15 on it. I think it's 15 amp. Any idea how many amps these motors pull?

 

[Speddmon]

if you're tripping two separate breakers...I'll bet you're pulling more than 15 amps....which you already know.

The question is why?

 

[steelandcanvas]

Remove the motor from the circuit and take an amp reading. You shouldn't have any draw at all, if you do, it's in your wiring to the motor, if not, it's your heater motor. If you don't own a DVM, just disconnect and listen for the circuit breaker to trip, on not.

 

[renovate7]

Just got in and it's already dark thirty here. I'm going to pull an amp reading tomorrow. I am wondering if anyone has heard of a new motor going bad? I hate spending another $ for something this new. Thanks

 

[steelandcanvas]

Just got in and it's already dark thirty here. I'm going to pull an amp reading tomorrow. I am wondering if anyone has heard of a new motor going bad? I hate spending another $ for something this new. Thanks

Stranger things have happened. New motor going bad? Last on the troubleshooting checklist, but not to be overlooked.

 

[Speddmon]

Just got in and it's already dark thirty here. I'm going to pull an amp reading tomorrow. I am wondering if anyone has heard of a new motor going bad? I hate spending another $ for something this new. Thanks

As strange as it sounds, when you're in the industry (electrical maintenance) long enough you see a lot of bad stuff right out of the box.

A saying I've been repeating to people for years goes like this..."New, only means it's never been used. Not that it's any good"

 

[rneely]

Just had a similar problem today on my Deuce. I was warming it up, letting it idle, it is in the teens here in Michigan. I turned on the blower to warm the cab and it ran for about 20 minutes ok. Then just as I got in to start my run around the neighborhood, the cab fills with a light smoke and the blower quit. So where do I look for the fuse and/or do you think my motor burned up. It is dark now and too cold to look until tomorrow. What manual covers this?

 

[Speddmon]

If you had smoke....it should have had a distinct smell to it of the burning windings if it was the blower motor. There is no fuse, just an auto-reset breaker on the firewall. From the sounds of it, your blower is toast...I could be wrong though

There is also the possibility that if you were running on "low" speed, the resistor could have burned open...see if it will work on "high" speed

 

[rneely]

Speddmon, thanks for the fast reply. I agree it had that wire burning smell and only lasted a very short time. Do you know where I can get a new motor and which manual covers this area?

 

[Speddmon]

not a clue on the new motor...maybe find a used one at a salvage yard.

Until you check the "low" speed resistor out, I would not just to any conclusions...LOL

As far as manuals go TM 9-2320-361-34 page 2-31 covers the winterization kit's and the troubleshooting of them (these troubleshooting tips are for the fuel fired heaters).

TM 9-2320-209-20-2-2 has a more detailed heater troubleshooting procedure starting with Chapter 82. It says that it is for the engine coolant heaters, but everything in the troubleshooting section covers the fuel fired heaters.

 

[doghead]

Do some searching , replacements have been discussed before. I think NAPA was one source. Saturn Surplus echos in my head also....(no funny comments please)

 

[steelandcanvas]

Saturn Surplus echos in my head also )

That explains some things.

 

[renovate7]

Thought I'd give a follow up. My motor is pulling in excess of 50 amps for the brief time it runs before the breaker trips. I only have a single position toggle switch to turn it on, giving me high speed only. Does anyone know if the original 3 position switch is straight thru 24 volts to the motor on high or is there a resistor in line at high speed? I can see that if this motor is not designed to be run on a full 24v it would burn it up but I don't think that is the case here. Saturn has new motors for under $50. I tried to get one at NAPA but is was non stock and expensive. I have John Vara in Georgia, who has a LOT of Deuce parts, looking for a used one for me now.

 

[steelandcanvas]

The resistor is used for the low speed, and the motor is wired "straight through" for high speed. No resistor on high speed. The drawing below will show you how it's wired. Drawing courtesy of "Cranetruck".