My 1999 Accord V6 with 180k miles has started overheating. The fans will not run unless the A/C is on. I replaced the coolant temp switch A, because the fan came on when I jumpered the pins of the fan connector. The fan will not come on, even when the temp gauge goes all the way to the top. Jumper the pins or turn on the climate control, the fans kick on, and the temp drops. Tested the old temp switch in boiling water and it tested fine. Tried spreading the pins on the temp sensor in case the connection was just bad and that did nothing.
Otherwise, the system seems to work fine. Top coolant hose gets hot first, then bottom gets hot after 10 minutes. The heat works, and I didn’t see any signs of exterior leaks. What else might keep the cooling fans from coming on?