Attic Fan Issues, Troubleshooting, Common Problems!

today what we're going over are common problems with the attic fan and with the thermostat that turns the atticfan on and we're going to be going over troubleshooting tips to allow you to quickly diagnose the problem to adjust the thermostat we just use a screwdriver and you leave this cover on and we typically set these at 90 degrees first things first we want to determine if we have power to the thermostat we can use a non-contact voltage sensor such as this and place it near the wire so that tells you that we do have power let's go ahead and turn it off we don't normally have a switch this close now we don't have power so we're going to take this cover off and we're going to also measure for voltage at the wire nuts before we continue so we have these two wire nuts for the incoming power wire and then you have this wire nut right here this black wire and that is the wire that you're switching the hot wire between here and here so the common is connected directly to the fan but we're going to measure for voltage just to make sure that we don't have any right now you see that we're reading zero volts okay so now at this point i'm going to go over to the attic fan and we want to go ahead and push the the fan blade and see if the fan is seized we didn't want to do that until we confirmed that we had no power over here the most common problem with the attic fan is that the bearings get seized and that's just due to the weather here and you can see that the the blade right here doesn't want to move and that's due to these sealed bearings inside of this this motor right here there's no way to oil these sealed bearings so we know that this attic fan needs to be replaced we know that right off the bat we don't want to try to put oil in there we don't want to try to spin it until it frees up we just need to replace this but say that this did spin fine now we need to go back over here to continue the diagnosis next we're going to turn the power on and then we're going to work with the switch right here which is the the thermostat we would normally have this set at 90 degrees like on this cover right here it's right at 90. so inside the building you're typically going to have it around 70 75 and so up here you would want this fan running anytime it's above 90 degrees and so you would adjust this accordingly but first we're going to turn the power on and we're going to test with our multimeter we'll put one probe into common we're going to put one probe into this hot we're going to see if we have any voltage so we're going to turn it down to a lower temperature now we see that we have 120 volts so if we were to turn this back up again you see that the switch is working properly and so let's see right about here is where it's turning the fan on so if we were to put the cover back on let's turn the power off for a sec just to be safe if we were to put this cover back on we see that it's turning the fan on and it says that it is about 78 degrees up here right now i have a bead temp sensor and it says that we're at 78.79 degrees so that's how you can tell it's going to switch any time that the temperature in the attic is higher than what you set it out on the dial and so we would normally set that at 90 degrees we know that this switch is working properly now sometimes you have a manual push test so that will bypass the temperature switch right here just to see if your attic fan is going to run we're going to move on to our last test and we're just verifying that our power is off right now which it is it's off right here at the switch and we verified it with the multimeter so the next thing that we're going to do is if that motor does spin we want to see if maybe the windings have opened up and we can do that by testing the electrical resistance on the hot and common wire leading to the fan so these two wires right here to measure electrical resistance we're just going to press this so that is the continuity button we don't want the beeping noise we're just going to go to electrical resistance and we're going to put one clamp on one wire one clamp on the other wire and you see that we're reading mega ohms so that means that the electrical windings have melted and opened up and that was because that the motor bearings were frozen so the the motor windings are bad in this motor so sometimes even when it free spins those windings may be bad so if we did have electrical resistance obviously when you touch these it should be very close to 0.0 ohms but you will have some electrical resistance going through that motor so as you can see those windings have opened up so most of the attic fans don't have a capacitor they're usually a shaded pole motor so you don't have to worry about a capacitor failing remember capacitors fail due to high heat and right here these shaded pole motors when these are mounted uh just like this on the on the gable vent sometimes the older ones will have an oil spout that you can put some oil in here and here but typically the ones that are mounted up here they have no wheeling mechanisms and they're sealed bearings right there i don't know if you happen to notice during the video but this attic fan is very close to a ridge vent so a ridge vent is not supposed to work with any type of mechanical ventilation whatsoever so it just works with the soffit so hot air rises and so the soffits are all the way down over at the the base of the roof on the side of the building and then hot air it travels upwards and then exits right through the ridge vent so there's no purpose of having an attic fan right here because it's just going to draw air from the path of least resistance so it really doesn't make any sense at all so just draw air from here and pull it right in here you're supposed to have either gable vents on the sides or soffits to draw from and then you put this in the center of your attic up high so no sense in even having this here if you have a gable mounted fan like this you want to make sure that this is sealed here and it's sealed from here to the wall so basically you want it to be ducted over to your gable vent and this type of gable vent is not even any good anyway this one's not meant for a gable fan so it's going to block and restrict most of the airflow anyway so you really want to be particular whenever installing a gable mounted fan if you want to learn more about hvac and electrical troubleshooting and refrigerant charging make sure you check out our website over at acservicetech.com we have a bunch of free resources there such as quizzes calculators we've got articles quick tips to podcast make sure you check all that out we also have our refrigerant charging service procedures for air conditioning book workbook and quick reference cards there we also have our ebook over at our website and on itunes and google play and we have all of our physical resources such as our book our workbook and quick reference cards over on amazon hope you enjoyed yourself we'll see you next time at ac service tech channel

Channel: AC Service Tech LLC

Views: 95,798

Keywords: acservicetech, repair, maintenance, how to, fix, hvac, hvacr, how do you, test, ac, service, tech, check, measure, read, superheat, subcooling, refrigerant, procedure, voltage, charging, temp, multimeter, freon, attic fan, attic fan not working, attic fan not turning on, troubleshooting, diagnosis, thermostat, bad, broke, hvac course, hvac school, hvac class, hvac lesson, hvac training, attic, building

Id: iYKFdiF4JgA

Length: 6min 53sec (413 seconds)

Published: Sat May 22 2021