Engine room blower speeding up and slowing down

[duende19]

Hi - my first post 

2017 Cruiser 34. Recently noticed that in line 24v engine room blower was making odd noise. Then measured that voltage to the the fan itself was cycling between 14 and 10V every few seconds, thus speeding up / slowing down the fan. I changed the fan and it was the same. The fan only comes on (slightly delayed ) once the engine starts.

I took some more measurements : With the engine running the Engine battery at rest 13.3V. Service batteries at rest 13.3V. Engine started. Service batteries at constant 14.1V. Engine battery cycling between 14.1V and 13.8V in the same cadence that the fan is cycling louder and quieter.

Does anyone know which board this fan is connected to ? Cant see anything in the owner wiring diagram which is pretty basic.

[David Light]

Bumping up this post.

The engine blower appears to be 12/24V. As for the variable voltage this could be due to the alternator output. Have you tested the output on your alternator?

On my 2011 Cruiser 32 the engine fan/blower runs whenever connected to power (irrespective of whether or not the engine is running). I can not trace where/how this fan is powered as I would have expected it to only run when the engine is running. Does anyone have the wiring diagram for the engine compartment?