Air Conditioning • HVAC A central air-conditioner is an elaborate system that involves parts such as an evaporator, a compressor, a condenser, fans, and refrigerant to run through the unit. Like many household appliances, each of these components does their job both independently, but also in unison with the connecting parts and when one section of the system goes down, the entire performance falters. While each component in a central air-conditioner is critical, quite simply the unit will not work if the fan is not running. Fans in the central A/C both pull air out of the room to be conditioned and have humidity removed and also push chilled air through the vents throughout the house. When the fan goes down there is no way to cycle the air and thus the system is essentially stalled. It’s important to get the fan up and running ASAP or else the home will get uncomfortable in a hurry and you could end up damaging the compressor. There are a few ways to tell if your A/C fan is temporarily or permanently out of order.

The first is an inspection of the outdoor unit to physically see if the fan is turning. The condenser lines should be cold and the air inside the home should be cool. If the fan isn’t running at all or there is warm air blowing it’s time to troubleshoot: If the fan doesn’t start up at all it could be something as simple as a setting on the thermostat. Make sure that the power is turned on and that the settings are calling for ‘cooling’. If all the settings are correct but the fan doesn’t start it could be an overheated or damaged fan motor. In some cases, you can give the fan a ‘kick start’ by pushing it with a stick and if this occurs there is likely an issue with the capacitor. Similarly, if a fan won’t turn when the power is on but will rotate freely when shut off it could be the sign of a bad motor bearing. Trouble with the bearing will also result in wobbly or lopsided turning if the fan does run. The fan needs to run at an optimal speed for the system to function properly.

If the blade turns noticeably slower there may be low voltage running to the unit caused by issues with the control board or problems with the circuits. Also, the fan blade may have come loose from the motor shaft and is simply moving slowly because of a breeze or the turning of the shaft. interior wall ac unitOnce again a capacitor may also be causing issues with the slow moving fan.cost of hvac system new construction If your Central A/C fan is acting unpredictably, starting on and off at random and shutting down in the middle of a cycle it could be a sign there’s an issue with the wiring or some loose components somewhere.how many amps does a ac unit use It’s normal for a fan to keep running for a short time after an A/C cycle while the compressor motor stops but a fan that keeps winding excessively there are likely problems in the circuit board or with the wiring.

As long as the A/C unit is running properly some homeowners may be willing to ignore a ticking, rattling, or buzzing coming from the fan area. In reality, it’s best to diagnose these sounds to make sure they aren’t leading to serious problems down the line. The first thing to check is that an obstruction isn’t hitting the fan blades as they turn or that the blades aren’t bent. Buzzing and humming are somewhat more sinister as they could present a problem with the motor or the bearings turning the blades. The common denominator with all these problems is that, although a visual inspection might locate the problem, the fix should almost always be done by a professional HVAC technician. It’s better to spend money for a service call and be guaranteed you fix the problem rather than buy unnecessary parts or do incomplete fixes that could end up costing more in the long run. Are you in Pennsylvania and need help with your HVAC system? Contact us today for a free quote!

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. Do a resistance check between the white wire and each of the colored wires. The higher the resistance, the lower the speed, with each color representing a different speed: i.e., four colored wires, 4-speed; three 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.