i own a 2000si and am having problems with my car starting to overheat. the temp gauge goes to about 3/4 the way up unless i start driving about 50-60 or turn on the heat. iv already replaced the water temp sensor and the sensor on the thermostat houseing. i dont think its the thermostat not opening up cause i waiting until it got hot and felt the lower radiatior hose and it was hot so im pretty sure the thermostat opens up, and the cooling fan isnt coming on. i already switched the relays around to see if it was that but it still doesnt cut on. what else could i try before replaceing the fan or radiator?