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Last night it stopped again and I tried to just turn the fan (from the thermostat) on without luck. I took a look at the blower and it seemed to turn just fine. I put my hand on the back of the fan motor and it wasn't hot to the touch. About 45 minutes after it turned off the blower came back and it was working normally.
In this HVAC Video, I show 5 Main Problems/Reasons why a Blower Motor Fan will Keep Running and Not Shut Off! I use a multimeter to measure the resistance ac...
- 11 min
- 650K
- AC Service Tech LLC
- What Does Short Cycling Mean?
- Additional Causes For An AC Blower Which Keeps Turning Off & on
- Conclusion
Heating and air conditioning units are meant to cycle on and off.This simply means they don’t just run indefinitely, which could burn out their motors. Depending on how extreme outdoor conditions are, your system should cycle off and then on every 10 to 20 minutes. So they’ll run for 10 minutes then shut off and wait another 10 minutes or so to sta...
The above issues dealt with a system that turned on and off after several minutes. But what if yours system is turning off as soon as you start it? Here are some typical reasons.
As you can see, there are a number of reasons why your AC blower could be turning on and off. Some of them may be as simple as needing to replace the batteries in your thermostat or repositioning your thermostat. Others may require an electrician or HVAC professional to diagnose and fix. Hopefully, there was enough info here to either help you fix ...
- HVAC Expert
- One of the 24v Electrical Safety Switches Inside the Furnace Has Tripped. A furnace may have the following safety switches. If any of these are electrically open, the blower motor may turn on and stay on until the switch automatically resets or is manually reset.
- A Bad Thermostat. If the thermostat is not calling for heat, air conditioning, or fan to turn on, yet the fan is running, a quick test can be performed to see if the thermostat is the problem.
- Bad Thermostat Wiring. · This may be due to a thermostat wire being flattened by a staple, or having been chewed by an animal (e.g. mouse, squirrel, etc.)
- The Control Board Has Closed Contacts that are Welded Together. · Turn on the power to the furnace. · If there is no power measured on the G, Y, and W terminals, but there is 120 volts on relay contact going to the blower fan motor either on the heat or on cooling terminal, this indicates that the contacts inside the relay are welded together.
Mar 28, 2021 · 1. Fan Only Switch. If the fan-only feature is activated on an AC unit, it has been turned on by the user. Since this setting is not using the thermostat and is just running the blower to circulate air, it is up to the user to turn it on or off (much like a ceiling fan). If you can hear the fan running and you can feel air coming out of the ...
Faulty Thermostat: If both the fan and either the cooling or heating system are running unexpectedly, you may have a faulty thermostat. Broken Relay Switch or Short Circuit: If only the fan is running, there may be a broken relay switch preventing the settings you enter on the thermostat from being sent to the fan.
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Jun 2, 2022 · Usually, when the relay switch is broken, the fan will continue to run by itself. This happens because there’s no communication between the thermostat and the blower fan. Now, if it’s a short circuit, both the ‘ on ’ and ‘ off ’ commands you enter typically won’t get sent to the blower fan. As a result, the blower fan will ...
