Fan motors are the unsung “heart” of HVAC equipment. They work unobtrusively and quietly for years, often under tough conditions. They don’t need a lot of love, but they do need periodic attention and it’s up to you to provide it. The cost of overlooking regular testing and maintenance of motors can be an HVAC system that grinds to a halt, so be sure to check the motor on every maintenance and service call. When you arrive on a jobsite in which a unit’s fan motor is not working or the high-limit switch has tripped, the first thing to check is power to the motor and/or unit. If there is proper voltage, check the low-voltage control circuit. Check for proper voltage at the transformer and check for a fuse in the low-voltage circuit. Make sure the circuit breaker is not tripped (or the fuse is not blown). If the circuit breaker is tripped (or fuse is blown) or if the transformer is bad, it could indicate a short in the motor. In that case, check the windings in the motor before turning the power back on.

To check the windings of a motor for an open or a short, you’ll need to measure the ohms. If the unit has a 120V motor, it will most likely have three or four colored wires (black, red, yellow, and blue are common), a white wire, and two brown wires. Champagne Indian Wedding DressDo a resistance check between the white wire and each of the colored wires. Black Fox Puppies For SaleThe higher the resistance, the lower the speed, with each color representing a different speed: i.e., four colored wires, 4-speed; Wedding Dress In Sweet Anniethree colored wires, 3-speed. You want to see a resistance reading. If you get a zero reading that means the motor winding is shorted and may be the cause of the tripped breaker/blown fuse. If you get an infinite reading (overlimit or OL on most digital meters), that indicates an open motor winding.

If either of these conditions exist you will have to replace the motor. When checking the ohms on motor windings, many technicians have difficulty determining an open winding vs. a shorted winding. But it’s really not hard to tell the difference between the two. It should show a resistance. If it shows a zero reading it probably means the windings are shorted out. If it shows an infinite reading, that means the windings are likely broken or open. A good trick to remember this is that an infinite reading means the greatest resistance in the world. It’s like an open door leading to infinity — in other words, an open winding. Meanwhile, a zero reading means the load is taking a short cut around it — in other words, a short. That’s just a simple trick to help you remember that a zero reading means a short, and an infinite reading means an open or broken winding. Just because a motor is not running doesn’t mean the motor is bad. If the power is correct and the motor is neither shorted nor open, check the capacitor (that’s where the two brown wires go).

A capacitor helps the motor run and gives it more torque. If a motor doesn’t have the torque to turn the blower wheel or the fan belt, it won’t start. So the capacitor plays a big role. The capacitors on most of residential blower motors are very small, so technicians tend to overlook them. You should discharge the capacitor before handling it. Using a capacitor tester, make sure the microfarad reading is within 10% of the rated capacitance on the capacitor. It will be a number listed in uF or mfd, depending on the manufacturer. If the reading does not match the rating, replace the capacitor. Checking 240V motors is slightly different because you will have two hot wires and most will be only single-speed. But you still ohm-out the windings to check for open and shorted windings and check the capacitor the same way. Finally, when doing a routine maintenance call on a unit, always check and clean the motor. One of the biggest problems with motor burnouts is dirt. The main thing to tell homeowners is to keep everything clean.

Most of the furnaces in heating climates are located in a laundry room or a basement. In those rooms, lint and dirt kicking up from inside the house can block the motor holes and make a motor overheat. When motors overheat they burn up their windings and bearings. So a lot of bad things can be caused by dirt. Remind customers that not getting their furnace cleaned annually could void the warranty.    Phil Rizzo is an HVAC instructor at Coyne College, Chicago, IL. He can be reached by email at prizzo@coynecollege.edu.January 28th, 2013 in Cars How to Repair Blower Motor Issue Time Required: 20 minutes Tools Required: Phillips screwdriver Cost to Repair: $45.00 Last week the blower for the A/C and heater stopped working on my 2003 Acura TL Type-S. The climate control unit will turn on, but you cannot feel the air because the blower will not blow. I tried turning it on Full Auto in both the hot and cold settings, nothing. I turned the fan knob to max and still nothing.

When you turn the climate control unit on, you can hear the compressor under the hood turn on. The problem is clearly the blower not turning on. After some online research, I learned that much like the seat heater problem, this too is a common issue for the Acura TL (as well as other Honda and Acura models). A friend had this same issue with his Acura TSX. The solution: Replace the blower resistor. I am not a mechanic. Follow my advice at your own risk. This repair is easy and cheap- so don’t be scared. Be sure to disconnect the battery, wear safety glasses, put on gloves, tie your shoes, chew with your mouth closed, and any other safety stuff that makes you not sue me. Most of the time, the problem is that the blower resistor needs to be replaced. But first check to make sure the issue is not something else like a blown fuse or corroded connector. The blower fuse is located under the hood (it is close to the firewall on the passenger side for my model). The fuse is labeled “Heater Motor” on the fuse cover.

If the fuse looks good, move on to the blower inside the car. The blower motor is located below the glove box. Notice the giant yellow arrow pointing to the location. Here you can see the blower motor and the blower motor resistor. Disconnect the wiring connector from the blower motor to make sure there isn’t any corrosion or connection issues. Sometimes corroded connectors [photo] will cause the failure. These are clean, this is not the problem… On to the blower resistor. Follow the wiring harness from the blower motor to the blower motor resistor. It is a white plastic trapezoidal-ish piece that is fastened by two Phillips head screws. Remove the two screws that fasten the blower resistor in place. This will allow you to pull the blower resistor down and disconnect the wires. Gently pull the blower resistor down and disconnect the wiring connector. Here is a close up of the resistor after it has been removed. These connectors look clean too. The metal side of the blower resistor had some crud on it.