Blower motor problems

[Elvis]

basic electrocnis. You have avoltage drop on a resistance somewhere in your wiring.
Circuit Breaker was the first try - but what voltages you measure there ?

could also be a bad crimp.
or a wire breaking
Could also be a bad Ground connection of your fan.
That's all easy to measure with a multimeter.

Which Ground do you use for your multimeter ?

[Paulonline3d]

Okay, got a chance to get back at it and replaced the old 25A circuit breaker with a new 30A. Cut off the clip-on connectors and put in ring connectors to insure good connection. Tested it out, and still same problem. On speed 4, still runs for about 5 seconds then circuit breaker pops, resets about 5 seconds later, then pops, etc.

I have the blower motor out while running, and the resistor pack. I can actually see each individual resistor come on at each speed, and start glowing within 5-10 seconds at each speed. Speed 1, even though the blower is not moving, I can see the resistor heat up and glow. Then turn to speed 2, and motor twitches momentarily, and different resistor starts to glow. Speed 3 has the motor moving, but seems very sluggish, and the 3rd resistor starts glowing pretty quickly. Speed 4 has all resistors off, motor spins faster, but then circuit breaker pops after 5 seconds.

I know it is not the motor, since I swapped in a new one and same results. Not the circuit breaker since that has now been replaced. Not quite sure where to go next. Hoping you guys have some more ideas. Thanks.

- Paul

[Paulonline3d]

Check the ground wire, make sure it has good connectivity to ground for the motor.

Here's a curiosity... I was checking the grounding to the fan again, used jumper cables to go from battery negative to ground screw on blower fan, and it actually performs worse!

I checked continuity with a multimeter between blower fan ground screw and stainless steel exterior, and got good continuity.

Any ideas? Thanks.

- Paul

[Rhye]

I see 2 options: either both blowers have shorted windings/worn bearings or there's some current leakage in wiring. Have you tried running the blower with filtering capacitor disconnected?

2be5c51ac04394b866e5ca7b43dc06b0.jpg

If there's no change, I'd measure the current draw of the blower powered directly from the battery (~30A range meter needed) - should probably be less than 20A if the blower's good.

[Bitsyncmaster]

I see 2 options: either both blowers have shorted windings/worn bearings or there's some current leakage in wiring. Have you tried running the blower with filtering capacitor disconnected?

2be5c51ac04394b866e5ca7b43dc06b0.jpg

If there's no change, I'd measure the current draw of the blower powered directly from the battery (~30A range meter needed) - should probably be less than 20A if the blower's good.

+1
Looks like you have no other options but to measure the current. Not many multimeters work above 10 amps so you need to find a DC clamp on type current meter. You just lamp it over the one wire going to the fan motor to read current. Make sure it's rated for DC current. A lot of them only work with AC current.

[David T]

Sounds like the motor (both of them) is drawing too much current. From your description all speeds work. The one that concerns me teh most is #4, full speed. For that speed there is no resistor but it pops the circuit breaker. That means you are drawing over 30 amps, WAY too much. I don't need a meter to figure a new 30 amp breaker is popping and know that you are drawing at least 30 amps! Get another fan motor.

[Elvis]

Here's a curiosity... I was checking the grounding to the fan again, used jumper cables to go from battery negative to ground screw on blower fan, and it actually performs worse!

I checked continuity with a multimeter between blower fan ground screw and stainless steel exterior, and got good continuity.

Any ideas? Thanks.

- Paul

Hi Paul - what menas - runs worse ?

Continuity with a multimeter ? We are talking here of resistances of below 1 Ohm, more like 0,0x Ohm.
You probably don't have such good measuring devices.

Measuring resistance AND (more important) inductivity of the motor while comparing it to a known good one would help.
Or replacing the motor again.
Is it the correct motor ? Did you perhaps get a 6V version ?
Pics ?
Current clamp is also a very good idea.

[Paulonline3d]

Okay, got some work done this evening. Bought a clamp-on meter to test DC amps pulled by blower motor (as suggested). Put meter on blower motor hooked to car, and on speed 4, hits 115A for about 3 seconds before circuit breaker trips. So definitely not good!

But, hooked blower motor straight to battery, and it spins up super easy, and clamp-on meter reads 8-9A. What gives?

Don't think it is the motor. Where should I be looking between the battery and the blower motor?

Thanks.

- Paul

[Paulonline3d]

Holy crap! Problem solved!

Someone who worked on the car in the past, put the wrong clips on the wrong terminals. Big fat pink wire with black strip was on the ground terminal. Switched that to the main terminal, with all others on ground terminal, and now works great on all speeds.

I like simple solutions! I just wish it didn't take me several weeks to figure it out. Thanks for your help, and patience. Maybe this will help someone else in the future to save a couple weeks.

- Paul