Coolant Fans won't switch off
 

Hi

I installed 2 eBay 80W slim fans a couple of years back and ran the car for a while then put it off the road for 2 years. I got it back out in March this year and since the. When the car geta warm the fans come on and stay on and don't go back off.

I had a coolant leak on the coolant reroute so as good practise I took it off changed the gaskets and put a brand new genuine Mazda thermostat in. Put it all back together and it's made no difference.

Ive also changed the green thermo sensor at the back for another one I had and changed the black fan switch at the front of the car.

The only other things I can think now are the relay controlling the fans or an ecu setup issue.

I'm running a DIY PNP supplied by Brain and haven't had any issues with it.

Please help it's frustrating me to death

Regards
Ronnie

what are the fan settings you're running

Hi

I'm not sure if I'm honest. Do I need to check the auto tune software I can't remember changing anything other than the settings that Brain mentions in his setup guide.

Pretty sure there is also a fan relay somewhere. These can operate in one direction and stick. If your fans are wited in parallel, this is another place to look. If they are switched from dedicated relays, then check your switch point in TS.

Thanks they are wired in parallel and I've located the relay. I'll try changing the relay and see if that works

or you could take all of 5 seconds to turn them on and off via megasquirt and know for sure if that's the issue before replacing anything.

One would assume that this has already been tested :)

but around here ...

I tried to change the relay for another 30A relay and initially the fans went off which was great. but I revd the car again to get them to come back on and they never switched off again.

What ampage relay should be used?

Tried to check auto tune and I can't see any settings to switch the fans off.

P = VI
V = 12V
P = 80W x 2 = 160W
160W/12V = 13.33A

Is the coolant temp dropping below the setpoint in TS? If it is not, the fans will stay on.

If the coolant temperature reading in TS is mucked (scale is off) that could hose you as well. Check out the online MS guides, make sure your sensors are working as expected in TS ...

based on how he refers to it (autotune) I'm guessing he has not a single clue how to even use megasquirt and would rather replace half the hardware on the car than open up tunerstudio, connect to the ecu, and go into fan settings to see what it's set at, which would take 5 seconds.
It should be under basic settings if you're on MS3

So the relay is fine. Ms shows temp steady at around 90 degrees C and fans cut in around 92 degrees then it appears the temp doesn't drop below 90/91 on the hinge on tuner studio

Thanks for the vote of confidence 18psi I've been around the forums for a while but the car has been off the road for 2 years and so I've forgot quite a lot about the tuning side of the DIY PNP. I'm using tuner studio.

90c is a bit low to have your fans turning on. Change it to 98c to turn on and then to turn off around 93c.

I'm on MS2

I don't know if MS2 have a fan outputs section, or you have to use a generic output. I know somewhere it is there though. What I assume is happening is you have a 90C thermostat and temps are hovering right above that, and so once the fans trip they never go off because it does not cool much below 90C.

That sounds right but I've looked all over auto tune and can't locate a setting other than under calibrate thermistor table it has the option of coolant temperature sensor

lars is right. I haven't used ms2 in years or I'd look it up for you. there is a fans settings screen though, you'll just have to really look around for it. ( I bet it's in one of the other sub-menu's that's not labeled "fans" like it is on ms3, so it might take a while to find it)

Ok I found output port settings then PM5 Warmup LED which shows the output channel as coolant and the threshold of 93.3 and Hysteresis 5.6 is that it?

I tried changing the settings to 98 and Hys to 3 and the fans still came I. Around 92 which indicates to me either I changed the wrong setting or the fan is been controlled by something else

Another strange thing is if you turn the car off with the fan then turn the ignition on the fan stays off until they start to run again assuming they reach a given temp and then stay on again