Resistor Amperage Draw Values

[Tim Martin]

I am looking for a table of what the amperage draw should be for blower motor on various speeds. I have not found this in MOD or in OEM Service Information. Surely somewhere in this industry there is values that can be gotten, but where?

[ricmorin]

I doubt you'd find a one size fits all chart. There are a lot of variables involved. Motor construction, plenum design, impeller design and even recirculation door position can affect draw. Numbers are generally 2 to 30 amps. I usually look at the fuse size in the circuit and expect the high speed to be no more than 75% of the rated circuit.

[Tim Martin]

Yea, I can understand that there is not a 1 size fits all chart, I was hoping that someone somewhere knows where I can find these values. The dealer in most cases doesnt even have values they can give. Says they dont check amperage draw. One dealer tech told me that I was making diagnosis too complicated to be checking amperage draw. Says, replace motor, resistor, and switch and you'll be fine.

[ricmorin]

Yea, I can understand that there is not a 1 size fits all chart, I was hoping that someone somewhere knows where I can find these values. The dealer in most cases doesnt even have values they can give. Says they dont check amperage draw. One dealer tech told me that I was making diagnosis too complicated to be checking amperage draw. Says, replace motor, resistor, and switch and you'll be fine.

LOL. Yeah, replace everything and you'll be fine. Typical.

My approach with a failed resistor is to check the draw after replacement. If it's less than 75% of the rated circuit on high, it's good.

[brianp87]

I look at the fuse rating and just know it cannot exceed that and go from there.

[Tim Martin]

Ok. Understand what's being said. So, if I replace both the motor and resistor, the amp draw is 16 amps on a 25 amp fused circuit, I should be fine. The issues I seem to be having is that we go through so many resistors even with supposedly acceptable amp draw. The high speed part of the resistor gives out. Am I just getting a batch of bad resistors or motors or am I having another problem? We use OEM parts in these applications.