HVAC: Indoor Blower Fan not turning on Automatically?

Ac Systemjdstorer12 asks:

Hey guys, having an issue with my A/C system here. To start, I'm an apartment dweller so I can't really tell what the deal is with the outdoor stuff as I don't know which one it is fyi, but on to the point. My indoor blower fan is not turning itself on automatically. If I turn the system on, with the fan on AUTO, the fan will never spin up, but the A/C does make noise like it's doing something (sorry for the laymans jargon but I'm not the most experienced with HVAC stuff.) Also if I try to switch the fan to ON after the A/C is already switched to ON, the fan still does not turn on. However, if I switch the whole thing to OFF, switch the Fan to ON, and then switch the A/C back ON the fan spins up and all is OK. If I switch the fan to AUTO at this point it will stay on like it's supposed to until it reaches the desired temperature, at which point the fan will turn off, but will not come back on again. So, any ideas what the issue could be here guys? Obviously I can just call maintenance and get them to sort it out, but before I do I'm curious if it's something really simple that I can fix myself. Also I'd just like to know for future reference if I move into a house and have to fix something myself. Thanks guys!


Could be one of several issues. Dirty or failing thermostat or loose connections are most likely candidates. Another option could be fan relay or control board. A more remote possibility could be a weak run capacitor. Call maintenance as that is why you pay rent. But in the meantime try tapping the thermostat while everything is set as it should be ( cool on, fan auto) if that does anything then it would most likely be the thermostat or loose wire connections. Do not open anything with the power on and I always recommend a trained professional.

James Bowman

National Technical Manager – HVACR 

Follow us on twitter, facebook, and LinkedIn