aw_wolfe

93 honda accord, automatic. The radiator fan is not coming on when engine gets hot.

If I turn on the air conditioner, both fans work.

If I disconnect the 2 pin thermoswitch and short the harness connectors, the fan does not work. However, If I leave the harness connectors shorted and turn the car off, the fan comes on (!?!), and immediately shuts off if I pull the short wire.

With the thermoswitch harness still shorted, Pulling the relay labeled "cooling fan" in the fuse box does nothing, no clicking. Replacing the relay with the one next to it (power window), which is same part number and nothing happens either.

Any thoughts???

Help?!

THanks,

Tony

jerry00

my gosh!!!

Muddy9069

My 94 was just doing the same thing... It was the relay. Mine had the power window relay in the spot also and it didnt work.

Muddy

JimBlake

Check out the radiator fan timer module. That's not the same thing as the fan relay.

F22B Prelude

First off, how hot is hot? Is it overheating, my fan rarely turns on, even after being driven all day.

JimBlake

Which thermoswitch are you shorting (in your first post)?

The one on the thermostat housing is responsible for switching the fan while the engine is running. The other one (in upper radiator hose neck?) is responsible for switching the fan after turning off the engine.

The fan timer module is responsible for deciding which fan switch to use.

aw_wolfe

JimBlake,

Thanks for the info. Yes, you are right, I did not realize until yesterday that there were in fact 2 different Thermoswitches A & B. I've 'hard' shorted the Thermoswitch A to keep both fans on while the car is running until I can pull out the thermostat and thermoswitch to test them. Any issues with doing so short term?

Anyway to determine which might be bad (thermostat or thermoswitch A)while still in car?

THanks again,

TOny

JimBlake

Whenever you're driving at least 20 mph, you don't need fans at all. So if your engine temperature is OK while you're driving around (especially climbing big hills), then your thermostat is OK. If your thermostat sticks open, then your engine will take forever to warm up.

The only time you need the fans is when you're going real slow (or stopped) so there's no air going naturally thru the radiator.

So now, with the switch A shorted, is your engine temperature gauge behaving normal? If so, your thermostat is OK. The only downside to shorting this, is how quickly you'll wear out the fan motor. (You could use a toggle switch.)

Finally, remember that the fan switch isn't supposed to come on at the same temperature as the thermostat. Your gauge will have to move up (above 1/2 scale) before the fan switches on. As long as it doesn't go very close to the top (red) part of the gauge.