AtoZ

vehicle is in signature:

Why do the fans have 4 relays ... or what is the differences in their function?

I referring to the 2 relays under the hood in the fuse panel that control the radiator and condenser fans; and the other 2 relays off to the side of the condenser fan that also control the radiator and condenser fans?

arkangel2487

there is a high and low speed setting for each fan

92civlude

There is a relay for the compressor, condenser fan, radiator fan, and there is a diode pack that looks like a relay. A relays function is to use low amperage to control high amperage cicuits. If you notice the wires at the fan connectors are a heavy gauge. As opposed to the wires in the control panel are small. It gets into cost of wiring, size of dash switches, size of ECU drivers, and Im sure, the manufacturer doesnt want high amps flowing up and down the harnesses. Why do you ask?

AtoZ

Well, that only accounts for 3 relays. I noticed that there are 2 relays in the fuse box under the hood on the passenger's side. And there are also 2 relays side by side out in the open, along the side of the condenser fan shroud.

Why do I ask? -- Why have 4 relays for two fans?

AtoZ

There is no source of information that I can find to back up that statement.

redbull-1

There is one radiator fan relay in the under hood fuse/relay box. The other relays in the under hood fuse/relay box are power window relay, dimmer relay, and headlight relay.

The 2 relays to the side of the condenser fan are the AC compressor clutch relay and the condenser fan relay.

92civlude

You dont. You have 1 relay for the compressor, 1 relay for the condenser fan, and 1 relay for the radiator fan.

AtoZ

RedBull & CivLude:

I think I came to this conclusion by reading some threads in the archives or gotten confused about it too easily. I thought perhaps the engine cooling system and the AC system operated both fans independently of each other. So, when you turn on the AC, then only the condenser fan is supposed to run, not both fans ... correct ?

92civlude

No, both fans are supposed turn on with either the AC running or with the thermoswitch command.

AtoZ

WTF !??? ... well, then where is the "AC relay" for the other [rad] fan?

92civlude

The AC comp. relay and cond. fan relay are bolted to the radiator bracket. The cooling fan relay is located in the underhood fuse box. The other relay in the underhood fuse box is the power window relay.

AtoZ

So, only one relay per fan but various sensors and switches that turn them on, correct?

92civlude

Yes