Hello all, this is my first post on this forum! I currently rent a bungalow built in the 60s, being a previous appartment-dweller I have a few dumb questions about some of the appliances! The topic for today shall be the gas furnace. It is a Carrier Performance 93 that uses natural gas and a blown air system, and it performed admirably at keeping us warm through the winter. Sadly there is no central AC installed by the owner of the house, and now that it is summer we feel this lack sorely after a few recent heatwaves! (I'm getting to the point, I swear.) When discussing this issue with a friend, he told me that even without AC it should be possible to leave the fan on (without heating) in order to circulate the air through the house. The basement usually being delightfully cool (despite its ugliness) this sounded like a wonderful proposition, which alas I have failed to implement since I can't figure out how. We have a digital thermostat upstairs (Sears brand). It has the following buttons: time, prgm, run, hold (the last two have 'fltr' underneath) and switches: fan (on/off), system (cool, off, heat). I thought that setting the switches to fan ON and system OFF would set the fan on without heat, but this does not seem to accomplish anything (no fan noise from the furnace, no air circulating through the ducts). I then thought perhaps there would be a button on the furnace, but the only switch I can find is the gas supply. Was my friend lying? Or is my thermostat not hooked up correctly? Or am I just too dumb to figure it out? I am more than willing to take pictures, but since this is not my house (rental) and I am a chicken I will not mess with wiring! Thanks in advance for your help.