Hello,
I have a 2000 Accord Lx 4 cyl. The problem I am having is that neither fan on the radiator is coming on (even with the a/c on cold). I have checked the relays and fuses and replaced both the thermostat and the radiator fan switch on the thermostat housing with brand new ones. I have bled the coolant system of air and still neither fan comes on after the car has reached operating temp. I can get both fans to come on if I jumper the radiator fan switch connector, but the switch will not activate the fans? I have tried 2 different brands of new radiator fan switch with no luck. Really confused as to what the problem could be as most indications point to the switch, but I have tried 2 different brand new replacement switches.

 

If you are jumpering the part 15 in this diagram and the fans come on then the issue is the fan switches you are buying. For cooling system sensors you need to buy Honda all the time. Don't mess around with parts store fan switches, they will not last as long, if they even work at all. Same goes for thermostats. Maybe when parts stores started making quality parts for cooling system it would then be ok to take the chance with them. When they fail and you don't catch an overheating car in time it will ruin your engine. It only takes seconds.

Don't forget when you crack open the cooling system and let coolant out you need to crack open part number 12 a half a turn until only coolant comes out, this lets all the air out of the system. It's highly likely this is your current issue, and not the fan switch being bad. When there is air in there, it doesn't allow the hot coolant to hit the fan switch and turn the fans on.

 

If the fans don't run when the A/C is turned on, the fan switches have nothing to do with it. Looks like you might have a bad A/C diode or a broken wire.

 

A 2000 Accord doesn't have an A/C diode. The image posted is related to earlier generations.

 

You might just bypass the switch and the computer and wire it directly off of the battery with a fuse. It will blow all the time the car is running. but that shouldn't be an issue, I don't think. Scotty Kilmer a famous mechanic for over 40 years has a YouTube video "Rewiring Electrical Power through the ignition switch"

 

Don't jerry rig your fans. Find out what's broken and repair it.

If nothing else it will make it hard to sell the car in the future. I would not buy a car that's had some "alternate" wiring done to it.