Engine room fan/ hot air exhaust

Calif. Ted · Sep 13, 2015

Usually an on/off switch, on Catalinas it's on bottom of instrument panel, think there's a breaker near it too. I can't remember where the French boats put it, look at engine and electrical panels for "Engine Blower" in French. I leave the switch on all the time so whenever the ignition switch is on it runs, maybe that is what PO was referring to.

DougM · Sep 14, 2015

I don't know about other models, but on my 323 the blower runs when the engine is running 100% of the time. According to the folks at Beneteau when I inquired years ago, the blower was wired to run when the key was switched on. I always assumed that its function was to 1.) vent the engine compartment prior to engine start as one would normally do if it was a gasoline engine as opposed to a diesel. 2.) provide some heat dissipation/ventilation while the engine was running 3.) to augment combustion air for the engine. There is no way that the blower would run if the key was switched off however .

gleason99 · Sep 14, 2015

On my 2009 Beneteau 37 there is a 5 amp breaker for the fan down by the batteries right behind the battery on-off switches, I would look for one that is "blown" down there, after checking to make sure the blower runs when connected to 12 volt power. My bet is it is the fuse since the Blower being that old is probably pulling max amps and popped the fuse.

Ron20324 · Sep 14, 2015

Don't know your year, but my 2006 B323 has a wire fused(4Amp) at the battery switch, to the BEHIND the breaker panel to splice to a wire that feeds a relay behind the Yanmar B (3YM20) cockpit panel. The relay is fed power from the engine panel switch. Also there is a neg from the neg batt switch straight to the blower. YMMV.

You should acquire manuals for ALL equipment on board NOW- before it fails. The fan also vents fumes, not just heat.

Gunni · Sep 14, 2015

Yes, the blower is on when the engine is running. Sounds like yours is burned out.

Syversens · Sep 14, 2015

We have a 99 361 with Yanmar and for us the fan comes on when we turn the key so motor doesn't necessarily have to be running.

Now, previous owner had the oil alarm disconnected on the control panel on our boat, I suspect that either he wanted to run the fan with motor off after a long day motoring (something that makes sense) or felt it was too loud at startup (less sense). Maybe your boats previous owner did something similar but to the fan.

Bronte Bill · Sep 14, 2015

Blower relay.

I have a B323 and the blower used to run all the time the engine was on. I've traced the fault to a relay behind the instrument panel. I purchased a new one from Beneteau but have not fitted yet.

QUOTE=donvanv;1240022]Does anyone know when exhaust fan is suppose to come on? Temp activated? Previous owner said it should come on when engine is running but it doesn't.

The engine room of my Beni 36cc has an exhaust fan to presumably take out hot air when it gets hot. However I have never found it running. I've only owned this boat a year now and have it in the pacific NW. Admittedly it doesn't get extreme temps here, but did have an exceptionally hot summer this year and had to motor several hours on a few 90 deg days and still no fan activity.

I have disconnected the two wires going to fan and made a temporary direct connection to battery and fan does work.[/QUOTE]

Gunni · Sep 14, 2015

Gunni said:
Yes, the blower is on when the engine is running. Sounds like yours is burned out.

Sorry, just noted that you were able to power the blower with a jump to the battery. There is a fuse in the engine compartment.

Stu Jackson · Oct 29, 2015

donvanv said:
Solved: It is wired into the ignition switch with an inline fuse which was bad. I don't know why a simple fan would need a fuse, so I quickly cut out the fuse and bypassed it.

A really, really poor idea.

Replace the fuse.

Why? Wanna burn your boat down? Didn't think so.

njlarry · Oct 29, 2015

The fuse is there to protect the wiring so you don't get an electrical fire if the fan shorts out. That's why you generally find them close to the power source.

TENACITY CS36T · Oct 29, 2015

Generally it's always on when engine is running and an additional on/off switch located at engine control panel in case you want to manually have it run at any other time.

Davidasailor26 · Oct 29, 2015

donvanv said:
Solved: It is wired into the ignition switch with an inline fuse which was bad. I don't know why a simple fan would need a fuse, so I quickly cut out the fuse and bypassed it.

Like the others have said, the fuse isn't about the fan, it's about protecting the boat from the wiring should something go wrong with it. Imagine that the wire chafes and rubs against the (grounded) engine block. You need the fuse so that the shorted wire doesn't burn and start a fire.

BigEasy · Oct 30, 2015

. I have read of your problems with the fan on the 323 models and I chartered a 331 that also had a blower. I find it odd that the 343 model doesn't have a blower; no mention of it in the wiring schematics nor the spare parts catalog. I certainly find that the engine room gets quite hot especially on warm days when running the engine. I did notice a plastic vent at the companionway that has a duct; I assume that it is to provide fresh air into the engine room for the air demands of the engine. Where is the blower vented on your boat? It wouldn't seem too difficult to install as the blower and duct for the 323, that is listed on the Beneteau online parts catalog, could be used for my application on the 343.

Ron20324 · Oct 30, 2015

Don't you have the exhaust cowls on the transom?

BigEasy · Oct 31, 2015

Here's the setup on the Ben 343. There are two 2' louvered ducts on each side of the companionway that traverse into the engine compartment for ventilation. There is another 3" spiral plastic hose/duct that traverses from the engine compartment to the transom where it terminates beneath a 12" soft plastic cowl with an open bottom. There is no blower attached anywhere.
I realize that it takes quite a bit of air to naturally aspirate a diesel; however, I was considering placing a blower inline with the plastic duct/hose to evacuate heat from the engine compartment. I am not sure; however, it seems that with the blower sucking air out of the engine compartment, that enough fresh air would be sucked into the compartment from the (2) 2" louvers beside the companionway. Another method of installing a blower may be to run another 3" duct/hose along side the existing duct/hose and terminate it inside the cover on the transom (there is enough room). The question that I ask is, how is your engine compartment ducted for air intake and exhaust?

trishark · Nov 1, 2015

On our B40 2009, there are two relays mounted to the bulkhead at the front of the battery compartment. These are Hella style cube "headlight" relays. One of those is for the engine fan. The ground of the coil on this relay is connected to the G1 circuit, another relay mounted at the alternator on the Yanmar. When the key is on, the G1 relay contacts ground the G1 circuit. This is also used for our windlass powered on only when the key is on. It has been a while but I think there is a fuse for the relay positive supply and for the fan. My fan fuse was also blown.
I installed a temp switch in my sound enclosure for my generator along with a relay parallel to the mfg supplied cooling fan relay. When the gen is not running, This switch/relay turns the fan on at 140 degF and opens/off at 120 degF. Cooling fan runs a few minutes after gen shutdown until enclosure is cooled. Occasionally, depending on how loaded the gen was, it will come back on due to heat in the engine. I have been wanting to install the same setup in my engine "room" but Beneteau's method of using the ground to turn on the blower relay is taking some serious thinking. I may need to install a diode to keep from activating other equipment. Leaving the key on to cool the engine adds hours to the engine meter and has the annoying alarm buzzer.