Yanmar 3YM20 - Engine Room Blower (relay / switch issue?)

[Jamme]

Hi all,

My Beneteau Oceanis 31 has an engine room blower that is engaged as soon as the engine switch (Yanmar 3YM20) is turned on, and that runs until the engine switch is turned off (no thermostat).

Today, the blower quit. After some reading, digging and testing, I believe there is a fault somewhere between the engine switch and the relay (electromagnet side). I arrived at this conclusion after doing the following:

-- tested the relay separately from the circuit: electromagnet switch closes when 12V is supplied; and

-- reinstalled the relay on the blower circuit, manually closed the electromagnet side: the blower starts.

Am I on the right track? If yes, any tips on how to test the circuit from the engine switch to the relay? Any schematics for the Yanmar panel switch? I am attaching a screenshot from the Yanmar manual, showing the panel type.

Thank you in advance.

[Wotname]

Originally Posted by Jamme

........

Am I on the right track? If yes, any tips on how to test the circuit from the engine switch to the relay? Any schematics for the Yanmar panel switch? I am attaching a screenshot from the Yanmar manual, showing the panel type.

Thank you in advance.

You are on the right track.

Now check if there is 12V on the end of the wire that comes from panel to the blower relay with the relay disconnected and when the engine switch is ON. If not, find out why - it will be either an open circuit (broken) wire or a fuse has blown.

However there is 12V on the wire while the relay is disconnected, now reconnect the relay and see what the voltage is with engine switch is ON. If the voltage is now much less than 12V, there is a high resistance in the wire from the panel. Look for corrosion or loose terminals in any disconnect plugs.

Also confirm the relay has a good negative path back to the negative bus.

ll this assumes the rest of the engine panel and engine is still working correctly. If they aren't, then fix whatever isn't working first before worrying about the blower relay .

Good luck.

[Jamme]

Thanks Wotname!

[Bean Counter]

We had same problem with a fridge relay, it seemed to work, the problem ended up being internal problem with the relay, it would switch but the power coming out of it still registered 12V but not enough amps to start the fridge, probably a corroded terminal inside the relay, replaced for less than $20 from an automotive store. If you have another relay on the boat swap it over, takes about 5 minutes, this will at least eliminate this issue.

[tweitz]

Our Beneteau 323 also has a blower that goes on whenever the motor is engaged. Frankly, I am not at all sure it is necessary. I guess it cools the engine compartment a but when the engine is running, but I wonder if you really need it.

[mvmojo]

Don't forget Occam's Razor, "the simplest solution is often the right one" or "look for the simplest fix first". Check the switch at the panel first!

[GordMay]

Originally Posted by Bean Counter

We had same problem with a fridge relay, it seemed to work, the problem ended up being internal problem with the relay, it would switch but the power coming out of it still registered 12V but not enough amps to start the fridge, probably a corroded ... contact

Clean the contacts.