More blower troubleshooting help

flsurflover · Outlaw Joined: 16 Jul 2003 Posts: 131 City: Melbourne, FL

The blower in my '86 Mastercraft Prostar hasn't worked since I bought the boat a few weeks ago. I took the rear panel off behind the back seat, in front of the gas tank. Turns out the extra switch that somebody wired into the dash wasn't to a blown blower or a fuel pump, but a rear bilge pump that someone added. That works, but the original blower rocker switch on the dash doesn't do anything. All the dash rocker switches have a small light in the middle of the switch that is red when off and green when on. The light works and changes color, but never turns the blower on.

I cut the two wires, yellow and black, a few inches from the blower and measured the voltage. With the switch off it reads ~9V, and with the switch on it reads ~12V. Seems like it should read ~0V with the switch off, right? So I undid the blower from the brackets and the hoses thinking the blower must be bad since it doesn't run at 12V. But then I touched the two wires directly to the battery terminals and it ran strong.

On the blower was a paper tag that said you must use a 6 amp fuse, and I'm sure Mastercraft wired it correctly, but I can't find any fuses. Next to each rocker switch on the dash (blower, pump, auto, anchor, navigation) there is a button circuit breaker. I think the button is supposed to pop out when the breaker trips. Isn't this supposed to be the equivalent of a fuse? But it isn't tripped. I reseated the connections on the back of the breaker button, but it didn't fix it. I was surprised just how many wires and connections there are for all those switches and breakers. Not the easiest thing to figure out without a wiring diagram.

I'm guessing the 9V and 12V readings I got at the blower wires are because of bad connections at either the breaker or the rocker switch, probably not allowing hardly any current to pass so the blower can't run. Any other ideas, or advice on which wires to use to jump around the rocker switch and breaker buttons to test if they are bad?

OttoNP · Addict Joined: 13 Jan 2003 Posts: 848 City: MI

Your situation is seriously confusing...you are right, you should read 0 volts with the blower off and 12 volts with the blower on. If you did read 12 volts with the blower on and the blower worked when you connected it to the battery, that is just freaky weird....

I'd try measure the voltage when the blower is attached to those wires, for some reasons the voltage must be dropping when they are connected....

Nick
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flsurflover · Outlaw Joined: 16 Jul 2003 Posts: 131 City: Melbourne, FL

Problem solved! It was the rocker switch. Even though the red/green light on the switch was working, it was not closing the yellow wire circuit needed to run the blower. First I pulled the two wires off the circuit breaker and put them together with no success. Then I pulled the two yellow wires off the switch and put them together and voila! Blowage. I wired in a temporary switch until I can get replacement Mastercraft rocker switches. If I'm smart, I'll go ahead and replace all the rocker switches while I'm at it.

MrBlean · Posted: Aug 28, 2003 2:41 am Post subject:

Logic won through! Congratulations!