I was being facetious in my comment about the turning on the motor comment but apparently it didn’t come across that way. When a blower motor doesn’t work, you can’t turn it on. You can turn the fan switch on, but not the motor. If a light bulb doesn’t light and you’re trying to help someone diagnose it, you wouldn’t tell them to “turn the light on”, you’d ask them to “turn the switch on”. That was my point and apparently not a very good one.
I also didn’t want to be mean and call you out on your original post where you yelled at the OP (that’s what CAPS are). Your original post told the OP to “measure the voltage at the plug WHILE TURNING THE MOTOR ON AT ITS VARIOUS SPEEDS.”. Did you read the OP’s original post? They already did that:
If there’s no ground, there’s no voltage either. If you supply ground with your meter/test light and read voltage, then you know the motor is getting power. If you then measure across the pins on the connector and have no voltage, the issue is on the ground side. It depends on how the ground is supplied. When I was a tech, I helped several fellow techs that had misdiagnosed an issue because they did exactly what Dave did - they supplied ground with their test light/meter and thought the motor was getting power but the issue was on the ground side of the circuit.
Yeah it seems that a lot of people seem to think that a 2 terminal blower motor still uses case ground to chassis like the older 1 terminal ones did, and when you don’t use the same ground as the blower motor does, it can get you in trouble… But yeah if I had of just taken 30 seconds and double checked the blower motor (straight wired it) 1st it would have been a red flag moment and I would have checked the BM ground next instead of after the oops moment when I traced it back to that ground sided fuse (circuit breaker) box… Like I said, I knew better, just got lazy… lol
I used to work for a rotary compressor manufacturer that played cops and robbers between the operating group and quality control. Some of the foremen didn’t understand the operations and wouldn’t use test tools to fix the issues. I was a QA engineer in the machine shop and discovered solutions through testing that operations and manufacturing engineering were unfamiliar with. My tests showed what the problems were. None of them understood the chemical systems and I was continually fixing the problems they created there. I learned a lot in a short time period because they were so bad at what they did.
That’s for sure. It makes me feel like I’m not the only bonehead in the room. There’s also something very satisfying about making a mistake, learning from it, then being able to admit it to others so they don’t feel the need to be perfect all the time. It’s disarming. I’m not saying one should be lazy about not doing things properly, I’m just saying we all make mistakes and there’s nothing worse than working around a bunch of guys who can’t admit their mistakes, or ask for help, or worst, make you feel like a plonker for making a mistake.
