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PWM for cooling fans

PostPosted: Wed Mar 01, 2023 1:18 pm
by Anth73
My M84 currently controls two cooling fans based on engine temperature and air conditioning status. Fan 1 comes on at 80C and with the A/C compressor. Fan 2 comes on at 90C. Both fans are triggered at full speed by the M84 via a relay per fan circuit. Fan 1 is doing most of the work and I'm not getting the full benefit of my radiator and A/C condensor at idle.

I've had 30A fuses in each fan circuit occassinally blow on startup, so increased them to 40A. However, I am interested to know if the M84 can soft start the fans using PWM or other approaches that will let me run both fans simulataneously.

Re: PWM for cooling fans

PostPosted: Thu Mar 02, 2023 9:54 am
by Stephen Dean

If the M84 is only controlling the relays for the fans, there is no reason why you couldn't have both fans activating at the same time if that is what the engine is requiring. You could also drop the temperature that Fan 2 activates at to a lower temperature so that they come on closer together.

The Fan control function in the M84 does not have a 'soft start' or PWM control, in the Mx00 ECU's you have the option of using a Aux Table to do this, but the Aux Table axis in the M84 are fixed at Engine Speed Vs. Efficiency so this will not work.

Re: PWM for cooling fans

PostPosted: Fri Mar 03, 2023 1:14 pm
by Anth73
Thanks Stephen.

I received the USB cable and adaptor to connect my laptop to the M84 adn tweak the fan on / off settings for the thermo fan and AC fan outputs.

Re: PWM for cooling fans

PostPosted: Thu Oct 05, 2023 7:15 pm
by Kamay
hi guys! I have a question! Is there any different sensor for the radiator other then the cooling engine sensor? and where is located? geometry dash lite