Not building heat

Hi gang, got a heating issue with my Ramcharger. It barely comes up to the first mark on the gauge. I recently replaced the radiator with an aluminum 4 core unit. With the factory one, the gauge was in the center after the same half hour trip to work. I thought I had a 160* stat in it, but I replaced a 195* with a 195* so that wasn't it. I have a thermal fan clutch on it and I wonder if that is the culprit. It has very little free spin on it cold or hot.
I'm thinking about replacing it but would it be better to get a non thermal or thermal clutch for the winter?
Any other suggestions?
Thanks!