Engine blower not working

[CarinaPDX]

I think the procedure has been stated earlier, but perhaps I could clarify. Attach the black ground lead of the multimeter to good ground (12V-). Then set the multimeter to volts and check the reading at different points from the panel to the blower of the positive lead, testing both sides of switches, fuses, etc. Clearly if 12V+ is available at the blower then that is not the problem, but if there is not then home in on the point where it drops from 12V+ to 0V. Next switch to resistance mode and check the ground (12V-) lead from source to blower; the resistance should be near 0Ω to the blower - if not then locate the point where the resistance goes high. This could be in a corroded fuse holder or a broken wire hidden by the insulation (take a look at sharp bends). If it is in a stretch of wire it can be located by pushing a pin or needle through the wire at various points and testing that.

I see no indication that the blower itself is the problem, but if it is then replace it with a continuous-duty rated blower. Most marine blowers are designed to vent a gasoline-powered boat's bilge, for 5 minutes before startup, and then be shut off. They use bushings instead of bearings and have a typical life (MTBF) of 1000-2000 hours. A quality blower for continuous venting of a diesel engine compartment will have ball bearings and will last for tens of thousands of hours. I have this 4" blower (they also have a 3" version): https://deltatsystems.com/product/4-inch-dc-blower/

Greg

[SwellGuy]

Your meter is set to "AC" - Likely this is a 12VDC or 24VDC component, yeah? Measure DC voltage and get back to us.

[CarinaPDX]

Originally Posted by SwellGuy

Your meter is set to "AC" - Likely this is a 12VDC or 24VDC component, yeah?

Nice catch!

[Svsumurun]

And seeing as we are talking about how to use a meter , it's a bad idea to ever use your ohm meter when the circuit is live - always disconnect the power source , there is usually a fuse in them , but you wouldn't know it blew , then all of a sudden - every thing has an open circuit .

[Lambretta]

Originally Posted by romel

The engine blower on my Jeaneau Sun Odyssey has a thermostat that runs on one of the power lines. (Not sure if its the positive or the negative now) So the blower only comes on when the engine room temperature rises above the preset value of the thermostat (usually after 20 minutes or so of motoring) and will stay on till the temp comes back down. The blower runs independently of the engine circuit so that it will stay on even with ignition key turned off. I prefer it this way as it helps cool the boat down when I get to an anchorage. Normally the blower will stay on 15 to 20 minutes and cycles off /on several times after the engine is turned off as the engine radiates heat. Understandably ambient temperature makes a lot of difference. This difference is easy to notice in winter as the fan will take longer to start and is quicker to turn off.
In my experience the fans (even the name brands) do not last longer then 2 to 3 seasons. So the last time I replaced with a much cheaper unbranded one which has been there for 2 seasons now. In that time I have never had a problem with the thermostat. I check the thermostat by blowing a hot hairdryer on it to simulate a hot engine room. Do make sure there are no fuel fumes in the engine compartment before starting a hair dryer.
If you supply the motor with DC directly from a battery and it runs OK then start following your power supply lines.
Hope this helps
Ron

Thanks for the useful information in your post
Would you mind sharing which blowers you have been using and the latest one you have fitted

[wingless]

Originally Posted by romel

The engine blower on my Jeaneau Sun Odyssey has a thermostat that runs on one of the power lines. (Not sure if its the positive or the negative now) So the blower only comes on when the engine room temperature rises above the preset value of the thermostat (usually after 20 minutes or so of motoring) and will stay on till the temp comes back down. The blower runs independently of the engine circuit so that it will stay on even with ignition key turned off. I prefer it this way as it helps cool the boat down when I get to an anchorage. Normally the blower will stay on 15 to 20 minutes and cycles off /on several times after the engine is turned off as the engine radiates heat. Understandably ambient temperature makes a lot of difference. This difference is easy to notice in winter as the fan will take longer to start and is quicker to turn off.
In my experience the fans (even the name brands) do not last longer then 2 to 3 seasons. So the last time I replaced with a much cheaper unbranded one which has been there for 2 seasons now. In that time I have never had a problem with the thermostat. I check the thermostat by blowing a hot hairdryer on it to simulate a hot engine room. Do make sure there are no fuel fumes in the engine compartment before starting a hair dryer.
If you supply the motor with DC directly from a battery and it runs OK then start following your power supply lines.
Hope this helps
Ron

That was one of the modifications I installed onto my boat.

My boat has gasoline engines and the factory fitted a pair of SHURflo 4" 220 cfm yellowTAIL blowers to extract possible gasoline fumes. The intake for these blowers is down low in the bottom of the engine room.

Operation of these blowers has minimal effect on the internal engine room temperature. That is because gas fumes are heavier than air, so the intake must be low, but warm air rises, so sucking from low is not optimum.

On my boat the engine room is encased in thick insulation and weatherstripping. This contains the heat and noise from the engines.

The problem with this configuration when operating in a warm / hot climate is that the closed engine room temperatures will climb when the engines are shut down, such as stopping for an on-hook lunch break.

With my gasoline engines under these conditions I would suffer vapor lock and would be unable to restart my engines. I tried the Factory Service Bulletin tips, but the last step was always to decrease the engine room temperature.

The only effective solution without boat modification would be to open the engine compartment when stopping, but that didn't work on-hook, because guests would want to sit at that area, using those seats and table.

My solution was to add an additional pair of these 220 cfm blowers to suck engine room air out to exterior exhaust under thermostatic control. The NTC sensor is placed near the exhaust elbow, as is the up-high air intake. The air intake is very close to the fuel rail.

This is a perfect solution!

Now when I drop anchor I hear my blowers kicking on and off automatically to maintain the engine room setpoint temperature that I currently selected at 45°C.

A 12VDC thermal controller was purchased off eBay and was installed per the ABYC standards.

It has been working great for years.

[B4A]

This is how I trouble shoot and fixed the issue in the end:

1) I changed the connection at the relay from pin 87 to pin 87a so that the circuit is always closed. The blower worked!

2) My issue was that I didn't have power on pin 86 of the relay. The power comes from the alternator. I did't have continuity on that wire because the electrician who installed my Sterling disconnected that wire for some reason, folded it, and taped it around the harness. Go figure why he did that.

So I only simply had to reconnect that wire to the alternator...

[Lambretta]

Due to what I have learnt on this post ....... I am looking at fitting the Delta T Systems blower that IMHO should have a longer life of the blower motor

12VDC 4IN DIA FAN BLOWER IGN PRO


Delta T Systems

Product Name: DC Centrifugal Blowers - Ignition Protected, Blower 12 VDC 4"

Sku# 214987

Item ID DLT 500-304121IP

Does anyone have any experience with this unit and its performance and reliability. YOur feedback would really be appreciated.
I am open to recommendations. I am trying to avoid using a 300 hour rated blower. The reviews on the JABSCO units rated for 5000 and 10 000 hours is not great
Thanks