I want to be able to run only the fan during these hot summer days to cool my manufactured home. When I manually set the thermostat to "fan only", the fan icon shows on the thermostat as though it's operating, but the furnace fan doesn't turn on. I know this can be done as I've done it in other homes I've owned. I did install a new electronic, programmable thermostat last autumn - could this be causing the problem?
Thanks!

From what I've found for wiring diagrams, your furnace doesn't have the seperat relay needed for fan only function. It uses a basic two wire thermostat control, not three wire control. Its either on or off no fan only mode. Your local heating and cooling contractor should be able to retrofit a really for fan only operation if you wanted to do that, I wouldn't recommend doing it yourself as damage to you furnace could result.
Hope this helps