fans not comming on and after short drive radiator boiling into overflow reservoir

Hi , Have a new water pump, new radiator , new hoses, new temperature sensor on
radiator but still it boils out to the overflow... although the temp gauges on the dash
says heat is perfect.
When you turn on the inside fan/ac the fans come on ...but that's it. I don't think power
is getting to the coolant temp sensor to make the fan go on. I check all the fuses I
could but not those box complicated ones. No water in oil no oil in radiator...otherwise
runs beautiful.  HELP!!!! one frustrated dude. Brought it to sears auto...and the guy
plainly lied... assumed I was ignorant...said I need a 1500 head gasket change. He lied
on the symptoms and so no.. the head is nowhere near blown. I know that was just a
bad mechanic...almost never run into situation. But it does make me boil over a bit...
bada bump!! Thanks in advance for any skilled guys know how to resolve. to me - I
need the power back to the fans.. first check those relays then more electrical testing.