98 Honda Accord EX, 4cyl, 4 door.
I have replaced the thermostat, fan switch on the thermostat housing, and the relays are still in working condition, but the fans will not turn on unless the AC is turned on. The temperature gauge shoots all the way to the red when stopped at a light. The new fan switch was working about 2 weeks ago, but recently stopped.

 

First off, how's your coolant levels? Topped off and bled? How's your radiator cap, have you witnessed coolant travel back and forth from overflow recently? Ever? Also check if it is actually overheating, don't just assume because a gauge says hot that it is hot. Do both rad hoses feel relatively similar after a drive? I could go on forever but start with the basics. Then get back with that info