cynikal

I have only had this '93 for a year now and just changed the cluster over to a gauged set. Changed out the oil sending unit and Temp Sending unit (yeah that sucked). the gauge is reading and the temp slowly climbs to over heating, it stops around 210 for a few secs - just enough to get my hopes up then starts the slow climb. I plan to do a flush (thermostat, hoses, and fliud change out) tomorrow night, but while snooping around noticed my Aux Fan not kicking on. It will turn on and off with the air conditioner.

Could the front sending unit be bad?
Could the relay be bad (i assume not due to it kicking in with the air con.)?
Could I have damaged the rear sender causing it to read bad - I did cuss it a couple times?

thanks for the help.