I have a 3.5ton Trane heat pump that has been set for the "Enhanced" ICM fan control in cooling mode. This year I think that the fan has not been blowing as hard in cooling mode. I had my service company come out and basically they changed the DIP switches so it always blows full speed when cooling. The DIP switch combination they used isn't listed in the air handler installation instructions and they seemed to spend a fair amount of time reading the instructions, so I'm not confident that they are that familiar with this system (it was installed in 2003 by them).

My question is how can I determine if the ICM fan speed control is working properly? I have set the thermostat at 65 degrees for more than 20 minutes to see if the fan eventually kicked in high gear but it never jumped up. According to the installers guide, the enhanced mode should run at 50% for one minute for "fast coil cooling", then up to 7.5 minutes for "dehumify" and finally 100% "if necessary, so 20 minutes on a hot day should've been sufficient.

Other info: in heating mode, the fan blows much harder (the installer guide says it should blow about 450 CFM/ton according to the original DIP switch settings). In cooling mode with the dip settings the servicer used, the fan also blows much harder. There is no humidstat in this system and it has a Chronotherm III.

Thanks for your help

Pete