最近发现自己的06 Honda Odyssey(270 K 公里）在等红灯时overheating when AC Not on，车载OBDII蓝牙App showing coolant 温度读数可到96C or even higher , 但是radiator cooling fan and condensor fan 都不启动; put AC on, (AC working properly without issues), both Radiator and condensor fans are on low speed immidiately，cooling down the Coolant termparature to normal 85- 87c, this is how i am doing now to keep my engine from overheating again.
my diagnose logic is: If both Fans are on when AC on, can we say the Fans' raleys/ fuses, Fans motor and wiring are all good? no matter if low speed or high speed are required? if so, should the CTSs(Coolant temparature sensors, 2 of them in upper and lower hoses) be the culpits which not functioning properly to close the loop to send signals to Raley to trigger the high speed fans? as there are two CTSs, one is on Thermostat housing to Upper hose (hot coolant out of engine), another one is close to lower hose back in engine, which one is controling the highspeed fans to kick-in when Coolant is over 90C? or both? if the CTSs are bad, how could the 车载OBDII蓝牙App still have a reading? or the reading is irrelavant to the switch on/off?
One more thing might need to add into consideration, I was adding in a transmission cooler two years ago in front of the radiator to cool down ATF to tow a small trailer, working fine, but not this year, no towing.
thanks!