# [EVDL] Troubleshooting a BLDC motor/controller



## EVDL List (Jul 27, 2007)

On my 94 Geo Prizm is an electric AC system. It's basically a Sanden 
compressor coupled to a 1.5hp Fischer BLDC motor with a Fischer 
controller mounted next to the radiator.

And now it's not working. Last year it would take awhile to come on, but 
would typically engage after a few minutes of driving and bouncing 
around. Now, nothing.

I checked the controller, with the AC switch on I have 300 volts to the 
controller itself, but the motor does not move. The controller is wired 
for 3 wires to the motor (phase A,B,C) three hall senders to the motor, 
a hall sender ground and a hall sender +5 supply. There do not appear to 
be any other on/off signals to the controller.

Before I take it apart though I would like to identify either the motor 
or the controller as the problem. So are there any good starting points 
for troubleshooting a BLDC motor as opposed to a standard AC motor? Can 
one buy a little BLDC motor and test the controller? Could it be the 
motor is simply stuck and not turning the compressor?

Thanks! It's a new thing to learn.

Chris

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## EVDL List (Jul 27, 2007)

Hi Chris,

Do you have it off the car, can you run it on the bench
(motor in a clamp of course) or can you reach the 3 phase
wires to see if it receives any voltage at all and in 
particular if it gets 3-phase AC?
The, the simpler tests - do the senders get +5 and GND?

Does the motor spin freely by hand/tool?

I guess you can try to find another controller and
replace the existing one or a working 3-phase motor
where you mount the hall senders if it does not have
them yet and test the controller.

I can make a convincing argument for either motor stuck
or moisture that needs to dry first for your Airco
working after a couple minutes but no longer, so it is
hard to help you troubleshoot without more data.

Success,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Chris Zach
Sent: Monday, April 05, 2010 4:05 AM
To: [email protected]
Subject: [EVDL] Troubleshooting a BLDC motor/controller

On my 94 Geo Prizm is an electric AC system. It's basically a Sanden
compressor coupled to a 1.5hp Fischer BLDC motor with a Fischer
controller mounted next to the radiator.

And now it's not working. Last year it would take awhile to come on, but
would typically engage after a few minutes of driving and bouncing
around. Now, nothing.

I checked the controller, with the AC switch on I have 300 volts to the
controller itself, but the motor does not move. The controller is wired
for 3 wires to the motor (phase A,B,C) three hall senders to the motor,
a hall sender ground and a hall sender +5 supply. There do not appear to
be any other on/off signals to the controller.

Before I take it apart though I would like to identify either the motor
or the controller as the problem. So are there any good starting points
for troubleshooting a BLDC motor as opposed to a standard AC motor? Can
one buy a little BLDC motor and test the controller? Could it be the
motor is simply stuck and not turning the compressor?

Thanks! It's a new thing to learn.

Chris

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## EVDL List (Jul 27, 2007)

I'm no real help on the mentioned problem, but I would suggest you 
need to verify that the compressor is not seized also. It it not 
uncommon for a sanden to fail tis way. Likely easier and cheaper to 
fix also.

Good luck

Kelly

Sent from my whatzehoosits



> Chris Zach <[email protected]> wrote:
> 
> > On my 94 Geo Prizm is an electric AC system. It's basically a Sanden
> > compressor coupled to a 1.5hp Fischer BLDC motor with a Fischer
> ...


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## EVDL List (Jul 27, 2007)

> Cor van de Water wrote:
> > Do you have it off the car, can you run it on the bench
> > (motor in a clamp of course) or can you reach the 3 phase
> > wires to see if it receives any voltage at all and in
> ...


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## EVDL List (Jul 27, 2007)

I'd say it's unlikely to be the motor, unless maybe it's the hall 
sensors. You can test them pretty easily: Supply them with their 
ground and 5V, then manually spin the motor shaft. The three hall 
signals, which encode the position of the permanent magnet rotor, 
should pulse on and off with respect to GND (measure them with a 
DVM). For the windings, you can try to look for back EMF as you turn 
it, but I doubt you're going to be able to see anything meaningful.

If either the motor or the compressor is seized, your controller could 
definitely be fine but protecting itself. You could also have a 
failed controller (though if it is an intermittent problem, it sounds 
as if it's mechanical, such as a bad connector or solder joint).

Hope this helps!
-Ben



> Chris Zach wrote:
> 
> > On my 94 Geo Prizm is an electric AC system. It's basically a Sanden
> > compressor coupled to a 1.5hp Fischer BLDC motor with a Fischer
> ...


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