Review on Zebra Instruments Protector Protection 120 240V by Tim Airy

So many factors went into turning my ECM fan motor off during a miserable Texas summer a few months ago. I had some vents clogged (as I found out later this increases static pressure which is bad for the motor) and the power went out during a thunderstorm while the motor was running. What can happen in this situation is that if the voltage drops during a power outage, the motor will start drawing more current to compensate for the lower voltage. Additional current can set the electronics in the engine control unit on fire. The motors themselves are almost indestructible, but the electronics that drive them are. not as much. And of course, you can't (usually) just buy a control box, you have to buy a brand new ECM motor, which costs anywhere from $700 to $1,000 (and if you don't install it yourself, add a service charge). Unless you're lucky and the "thermistor" (a sort of built-in surge protector in the control box) on the power board doesn't blow before damaging the rest of the electronics. This part costs a few bucks and is easy to solder into a new one on the top open power board. In my case, unfortunately, the thermistors were intact, but the fuse wire on the power board was blown. The only time I read about this error was due to a short circuit in one of the microcircuits on the control board. And the control board is filled with thick black goo, so you can't even see if something on it is blown or not (and I wouldn't be able to replace such components myself anyway). At this point I decided to go ahead and just replace the motor. A new one is $700 but I bought a used one off ebay for $230. Installed and reconnected the AC. Of course, I wish that it doesn't happen again. And as I found out while trying to diagnose/fix this issue, the ECM motors are exposed to line voltage the entire time the switch is on, unlike an external compressor which has a relay that controls the power on and off. This means that the ECM's engine electronics are susceptible to voltage spikes or problems occurring in your power supply, whether the engine is on or off. And then you have the problem of turning off the power while the motor is running. Despite all this, the engine has worked flawlessly for 14 years. So it could have been bad luck or something. But I heard about this unit and decided that if it does what it's supposed to do, $30 is very cheap insurance (compared to $1000 for a new engine!). It looks like it's just thermistors like the ones in the control box, but since you're mounting it in series in front of the motor, this device will take the hit first and sacrifice itself to protect your motor's electronics. If there is a thunderstorm outside, I also turn off the switch on the AC unit.