Engine room fan switch location

[john102345]

Hi Guy's n Girl's
Had my 2011 Bavaria 36 cruiser since 2017 but cannot find the switch to turn the engine fan on, normally just vent off the engine room before starting.
I have looked extensively in the engine bay around the fan pipework can't find it & also switched everything on & off at the Bavaria panel with no luck, there is an engine room/steps switch located just inside the door where it latches but this is for the engine room light.

Not sure if it's an extractor fan for fumes before starting or a fan to introduce new air into the engine room.

Can anyone assist?
Thanks
John   

[Yngmar]

Bilge fume extractor fans only make sense for petrol engines, which has a much lower flash point than diesel. Since you have a diesel engine, a bilge blower isn't needed. That's why you can't find one 

The engine is perfectly capable of drawing in its own air as long as there are ventilation gaps to supply the engine room.

That said, we did fit an extractor fan (near the top, not in the bilge) in our engine room, but only to avoid the air in there getting incredibly hot when the outside temperatures were already over 40°C in one Greek summer. This was mostly to avoid the watermaker in there overheating. The engine will also run slightly better with cooler (= denser) air, but didn't have any issues.

[tiger79]

As Ymgmar says, you don't necessarily need a fan.  Recent Bavarias have been fitted with fans which come on automatically whenever the engine is running - there's no separate switch.

[john102345]

Thank you for your replies
It's always been a bugbear of mine not been able to find the switch so that explains it, there is definitely the pipework there & have seen a fan in the topside of the pipe, so assumed a switch was lurking somewhere.

Thanks
John

[tiger79]

And, just as an aside, the fan in my Cruiser 37 is a 24v fan, presumably Bavaria specified that as it would be quieter perhaps?

[David Light]

The fan on my 2011 Cruiser 32 seems to have permanent power, irrespective of whether or not the engine is running. I can't trace the supply to this fan which I would have expected to be powered only when the alternator is outputting power.

The bilge blower is a 12/24v model just FYI, but the voltage at the blower is 12V.

[UAT Norway]

Sorry to use the topic, but I have the same boat, and my engine room fan is not woriking. Tested the fan with direct 12V, and it is running. I asume there is a fuse somewere between the altinator and the fan? But I can't find it.

[David Light]

I wish I could tell you, but I haven't been able to find a wiring diagram for my boat, nor trace this fan wire to find where it terminates. Yes, there should be a fuse, but besides the fuses on the DC panel and at the house batteries, I haven't found any fuses elsewhere. Any ideas?

[David Light]

I am opening this topic again to see if there are any other Cruiser owners who may know where the engine blower connect to?

[David Light]

I'm sharing my experience here in case it may help others in future.

Turns out the bilge blower / engine room fan is connected directly to the alternator, with no switch or relay in the cable. I would like to assume there is a fuse in this line, but I wasn't able to find this yet, so will add a fuse in line as protection. The clue was the white +ve cable to the blower (original Bavaria harness) and the white cable I found connected to the alternator (via a battery isolator).

My vessel is equipped with a Victron ARGODIODE Battery Isolator which isolates the alternator charge input from each battery bank (engine and house respectively). The blower was incorrectly connected to the OUTPUT 3 (cable to the house battery), meaning that this point is permanently energised as long as the house battery isolator is on (which in  my case is always).

I took the advice from another poster that the fan should only run when the alternator is running thus being connected to the alternator output. This is easily achieved with the battery isolator as I could use one of the outputs to connect the fan. In this way, the fan will run once the alternator has powered up and the alternator's charge regulator kicks in, which is excellent as the fan won't run until the engine is up to speed.

I could also have connected the fan directly to the alternator output/input on the battery isolator to achieve the same result since the internal diodes prevent house or engine battery current to return back to the alternator. My volt meter suggested this would work, but not sure if this is poor practice.

I've measured the engine room temp, starting with a cold engine and running for 20 mins, 1.) without the fan running, and 2.) with the fan running. The difference is 8-degrees  C less with the fan running, so definitely does a good job of channelling away engine heat from the interior, but especially the adjacent aft cabin (although I didn't measure the cabin temp to give an exact figure). I'll do to at some stage and share the results.