Thanks for all the good advice. I pulled the cap and noticed that the water started getting warm right away not cold with a rush of hot water when it opens, so it looks like my thermo is stuck at least a little open. I couldn't really see any movement of the water. I plan on pulling it in the next few days and then probably looking for a new one.
My fan pulls air through the radiator front to back. I haven't used it much in a situation where the screen became totally plugged, though I have had to clean the screen off.
Now that I know the thermostat is probably bad I hope I haven't shortened the life of my engine using it last winter. I have only put about 110 hours on it and have changed the oil twice (50 hours (break in) and 100 hours) per the manual.