Last night I turned on the heat at my retail storefront. The fan turned on but there was no air blowing through the vents. However, the return air was working fine and sucking air. I put a piece of paper on the return air vent and it stuck on the grill. If the return air is working, what could be the reason that its not blowing any air?
I tried turning of the heat and setting the fan to "ON". Same thing, return air working but no air was blowing.
Also, this wasn't the first time we had heat turned on this season, it worked fine for the last few weeks.