As the title says I am wondering if having the fan on all the time is a good idea? Obviously our cars benefit from any cooling improvements but is it a good idea in the warm up cycle?

 

Someone correct me if I'm wrong but I think that the stock Mazda thermostat starts to open at 85*C so having the fans on under that temp won't do anything. You can get a Power FC and set the fans to come on at 85C though. There's a setting in the datalogit that allows you to set the temp where the fans come on.

 

Thanks for your input....

The reason I ask is I'm in the process of bringing a 92 jdm fd back from the dead.
I've just had the engine rebuilt and now I have the car back, it seems like the fan has been set to always be on as soon as you turn on the ignition.
I thought It was odd but thought I'd ask you guys before I start questioning the shop and looking a bit dim.... 🙄

The engine is currently being run in, after this period it'll go back to the shop for a power FC, ast, alu rad and catback.

 

 

OK then, I'll go back to them and ask them about to change it back.

Thanks!

 

The fans also switch on regardless of temperature when the A/C switch is turned on. Just something to think about. Its possible that the fans are wired correctly to turn on at the appropriate temperature, but the system thinks the a/c switch is on.

 

So my car did a similar thing on the stock ecu when I had to plug in and unplug a bunch of stuff and it seems that the only reason the fans should come on with the ignition is if something is plugged in the wrong way or completely unplugged. I would start checking wires and plugs to see if anything looks fishy.

 

OK, that's some great feedback.

The AC is definitely off but maybe the system thinks it's on.
As I've just got the car back there is a good chance something's not plugged in correctly.

There is a thin wire coming down the right side of the engine bay and into the radiator. I've found that if I move it around the fan cuts in and out, maybe this is the culprit.

 

Good luck with that wire. On my '94, in addition to the AC switch turning on the radiator fans, the fans will also turn on if the parking or headlights are on, or if the cabin air fan is set to the 3 or 4 position. The engine idle kicks up about 150 rpm when the fans come on.

 

The factory FD fans are actually set to different duty cycles depending on engine conditions, triggered by a series of relays - they may be on, but not 100% duty cycle. It is detailed in the factory service manual.