Blower motor circuit confusion

Jun 13, 2017
7
Beneteau 37 Mhyc
I have a 2008 Beneteau 37 and this season my engine compartment blower motor would cut in and out just after start up, then run fine. During the last run of the season, it’s stopped coming on altogether. I ran power to the blower motor itself and it works fine. Can anyone help me understand if there is a fuse or where the controls are that drive the power to this blower motor?
 
Oct 22, 2014
20,989
CAL 35 Cruiser #21 moored EVERETT WA
Sounds to me you have corrosion on you wire connections. Check all the wire from the fan motor to the connector on the dc panel. If the ground is a little loose you can get that symptom. Use a wire brush to clean up the connections and then give it a try. If solved put a corrosion Block on the connections to make them last a bit longer.
 
Jun 13, 2017
7
Beneteau 37 Mhyc
My confusion is that I don’t know where to start looking. Tracing the wires is nearly impossible as they get bundled into massive plastic tube’s. Is there anyone that understands where I should look? Is the engine start unit in the cockpit the switch that energizes the blower circuit?
 

NYSail

.
Jan 6, 2006
3,048
Beneteau 423 Mt. Sinai, NY
The blower is activated by the ignition so I would assume it goes to back of engine panel in cock pit where there may be a Solenoid controlling the blower....... My blower is energized as soon as the key is engaged prior to starting. look closely at the small wires as on my boat I am finding all are stamped with a description.

Good luck
Greg
 

Gunni

.
Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
Dig out your Beneteau owners manual and scrutinize the wiring diagram. As I remember the blower does share a ground and there is a fuse and relay in the engine compartment. But your boat may be different. Your wiring should be marked with an identifying number to help ID wiring once it comes out of the loom.
 
Oct 22, 2014
20,989
CAL 35 Cruiser #21 moored EVERETT WA
Yes Russ. That plastic wrap is callled a wire loom. Sometimes they make it even trickier by hiding the wires under the deck or behind a wall. If you can find an ID or marked labels that match the boats wiring diagram it is a bit easier. Another possibility is to get a tone generator. Like this one (https://www.idealnetworks.net/us/en...per-testing/cable-tracing-tone-and-probe.aspx) Attach it to one end of the wire and listen on the other end till you ID the correct wire.

Or you can try the brute force method. Start cleaning all of the wire ends to eliminate corrosion. Then tighten all of the connections.
 
May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
In situations like this I recommend purchasing a fox and hound (aka tone and probe). You clip the tone on one wire end and can follow it using the probe. The real cheapies from Amazon don’t work the best. Good onwes are about $60.

Les
 
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Feb 21, 2010
330
Beneteau 31 016 St-Lawrence river
I have a 2009 B31 so same generation and general philosophy. My blower solenoid was activated by the alternator(?). I jury wired the solenoid to be always on and then put in a manual toggle switch from the blower positive wire. I situated the toggle just beside the control panel. Cleaned all contacts in the circuit. No more variation and I can control the use of the fan.
Pierre
 
May 24, 2004
7,129
CC 30 South Florida
The fan is just a 12V fixture and it is not even critical for a diesel engine compartment. It just helps by exhausting some of the heat. If the fan is activated by the "key switch" in the engine control panel then the wiring is ran inside the engine to panel wiring harness. Problems in this harness usually evidence themselves as intermittent failures. On older boats it is recommended the harness be visually inspected upon noticing any intermittent electrical issues. The problem arises from the harness being routed around sharp fiberglass hull edges and with the years of hull flexing the insulation on the harness wiring can get chaffed resulting finally in wire breakages or short circuits. Problems can range from false buzzer alarms to total loss of power to the solenoid. A visual inspection of the harness especially where it goes around corners can reveal failures in the insulation. Not saying this is your problem as I do not know how the fan is wired or controlled but just suggesting it might be worth taking a look at the harness. Getting back to the fan, I don't know how frequently you may want to use it (it's not critical) but you can hook up external wiring to positive and negative terminals, add a fuse on the (+) side and an On/Off switch and everything can be contained in the engine compartment. To be truthful diesel engine thrive on heat so using an exhaust fan in the winter time does not help any.
 
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
...The fan is just a 12V fixture and it is not even critical for a diesel engine compartment. It just helps by exhausting some of the heat. ... To be truthful diesel engine thrive on heat so using an exhaust fan in the winter time does not help any.
Uumm... Benny, without the fan, just where do you think the heat and fumes go???
 

DougM

.
Jul 24, 2005
2,242
Beneteau 323 Manistee, MI
Uumm... Benny, without the fan, just where do you think the heat and fumes go???
I would think that the engine itself would pull enough air through the compartment for combustion and enough residual air with it to keep air moving around the outside of the engine to avoid a continually increasing ambient temperature and fume buildup but not much more. The fan just pulls a small amount of outside air ( it is by no means a supercharger).

To me , a thermal switch added to the fan circuit would make sense to keep air moving through the compartment after engine shutdown until the internal temperature drops below a predetermined level.
 
Feb 21, 2010
330
Beneteau 31 016 St-Lawrence river
Russ,
I found the solenoid as indicated in the Bénéteau wiring chart for my boat, in the rear cabin close to the main switches. It took some searching to find although it is rather well indicated on the chart.
As others have said this isn’t a safety issue but it can be nice to let the fan work for a while after a long stint of motoring.