When a bin of tough or damp grain is sitting on a fan that won’t run, the clock is running too. Aeration fans also tend to fail at the worst time: they sit idle most of the year, then run hard, often around the clock, for a few weeks in fall. Whatever has been getting […]
When a bin of tough or damp grain is sitting on a fan that won’t run, the clock is running too. Aeration fans also tend to fail at the worst time: they sit idle most of the year, then run hard, often around the clock, for a few weeks in fall. Whatever has been getting worse since last harvest shows up in the first days they run full-time.
Most aeration fan calls I get come down to a handful of electrical causes. Here they are in roughly the order I find them, with what you can safely check before calling.
Before any of this — shut the fan off at its disconnect, and lock it out if anyone is going near the fan, the transition or the bin. Never enter a bin with aeration or unloading equipment that could start. Everything below that involves opening an enclosure, a disconnect or a motor box is electrical work.
This is the most common thing I see on portable and cord-connected fans. The fan gets plugged into a twist-lock receptacle on a post or a panel, runs at full load for days, and the connection heats up. A slightly loose or corroded contact means more heat. More heat makes the connection worse, and eventually the plug or receptacle discolours, melts or burns open.
Signs: brown or black marks on the plug face, a plug that’s hot to touch after running, a fan that cuts in and out, or a plug that won’t come out of the receptacle because the plastic has softened.
A burnt plug means the receptacle is almost always damaged too. Replacing only the plug and pushing it into the same damaged receptacle usually burns the new one. Both ends need replacing, the conductors trimmed back to clean copper, and the cord checked for damage along its length. On fans that are moved between bins, a hard-wired connection or a better-rated receptacle is sometimes worth it.
A fan that runs for a while and then trips is telling you it’s drawing more current than the protection allows. The usual causes on a farm:
Resetting it again and again doesn’t fix any of these, and on a lost phase it can finish off the motor. The overload tripping guide walks through the general process.
On single-phase fans, a motor that hums and doesn’t turn — or turns slowly and trips — is often a failed start capacitor or a start switch problem inside the motor. It can also be low voltage at the moment of starting, especially at the end of a long run. On three-phase fans, humming without starting points strongly at a missing phase.
Don’t keep trying to start it. A stalled motor draws several times its running current and heats fast.
Two electrical problems let the fan run while quietly doing a poor job:
If the grain isn’t cooling or drying the way it did in previous years with the same fan, the electrical supply is worth checking along with the fan itself.
Many bin sites now run fans through a controller, timer, thermostat or humidistat rather than a plain switch. When the fan won’t come on, the fault is sometimes in the control circuit rather than the motor: a failed contactor coil, a blown control fuse, a controller with no supply, or a sensor wire chewed through. The fan starts fine if it’s run manually and won’t run in auto — that pattern points at the controls.
This one is a planning problem that shows up as a harvest problem. A bin yard grows a fan at a time. Each one was fine when it was added. Now five fans, a dryer and an auger share the same service, and everything starting at once drops the voltage far enough that motors struggle, contactors chatter and breakers trip.
The fix may be staggering fan starts, running a larger feeder to the bin site, or talking to your power company — FortisAlberta or your REA, depending on the area — about whether the transformer serving the yard is still big enough. Measuring voltage at the far fan with everything running is the starting point.
Safe to check:
Stop and call when:
Rural addresses are routine for me. A range road and township road, a legal land description or a map pin all work. I service farms and bin yards across Red Deer County, around Lacombe and Innisfail, and up to Ponoka. Motors, starters, controls, bin-site feeders and fan wiring are all part of agricultural electrical service. Motor and starter work specifically is covered under motors, starters and VFDs.
Can I run the fan on an extension cord while the receptacle is fixed? Only on a cord rated for the fan’s full current and voltage, in good condition, and not coiled. An undersized cord on a fan running for days is how plugs and cords burn. If you don’t know the rating, don’t.
Should I just replace the motor? Find out why it failed first. A motor that burned out from a lost phase or low voltage will do it again on the same supply.
Why did all the fans work fine last year? Something has usually been added — another fan, a dryer, a bigger auger — or a connection has been slowly deteriorating. Harvest load is when it shows up.
Can you come out during harvest? Harvest is busy for everyone, but a fan down on a full bin is the kind of call I prioritise. Call and describe what the fan is doing.
Call 403-872-8698, or send a photo of the fan motor’s nameplate and the burnt plug, disconnect or controller through the service request form. The nameplate tells me the voltage, phase and horsepower before I leave the shop.
Todd Grasse, Red Seal Journeyman Electrician. Grasse Electric is a licensed electrical contractor in Alberta, insured and WCB covered.
Written by Todd Grasse, Red Seal Journeyman Electrician, Grasse Electric — Red Deer, Alberta. Published September 23, 2026.
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