Re: Blowers not working on one side...
If you're talking about the vents shown on the back of the boat, then they are not all normally hooked to a blower. While you're cruising, there should be air forced into the engine compartment from inlet vents. You can call it ram air or natural circulation but it's what keeps the compartment ventilated while underway. 2 minuted prior to start, when idling, or when traveling slowly, the blowers are turned on to ventilate the compartment since you don't have the natural inlet flow for ventilation.
Now if you actually have four blower and motor assemblies, that's another issue. But depending on the style, natural circulation may be able to provide flow past the stationary vanes.