3 Knob Cruisair Control Question

[SeaEric]

The center knob is the fan speed control. The original was a 3 click version. It got to the point that the speed didn't really change much no matter what position. The 2 others aboard have been changed to the variable rheostat version. My AC guy changed this one out with a "good used". Fan speed now varies from almost nothing to anemic. It doesn't really crank up like it should. All but this one work great. This "good used" knob may not actually be any good. I had a situation yesterday when the evaporator iced up - I'm assuming from not enough air flow. I took the panel off the bulkhead to take a look and right on the side of the fan control it warns about icing at low fan speeds. My AC guy is away on vacation and so am I. My question is: Can I just by pass the fan speed control by connecting the 2 wires coming out of it together? I assume this will give me full fan all the time, which for now would be fine. Thanks in advance for any help on this.

[Captain Ralph]

There are different models of these rheostats.
Voltage; 115 or 230Vac.

I have noticed, With no explanation but newer fans with caps, don't work well either.

Temp short the two rheostat leads together to give fan max voltage. It could be the fan starting to fail also.

[SeaEric]

There's nothing new about any of the Cruisair equipment on my boat. In fact, its still the original stuff from 1966 (I know, right?) with some mods - duct tape, bailing twine and such. It occurred to me that this rheostat could be a 230v version and my unit is 115. I'll give it a go on jumping the leads. Sparks and smoke will be my indication that it's perhaps not working.

[SeaEric]

It could be the fan starting to fail also.

I neglected to mention that this unit has two fans. They seem to be in sync.

[jim rosenthal]

If it was changed out for a 230v version from the original 115v version, that would probably slow the fan down. Try bypassing it, but wear gloves and have an extinguisher handy in case something occurs.

[bigbill]

jumping the 2 wires will put your fan in high speed... worked on my 46 and stayed like that for 4 years

[SeaEric]

If it was changed out for a 230v version from the original 115v version, that would probably slow the fan down. Try bypassing it, but wear gloves and have an extinguisher handy in case something occurs.

Sound advice. I'm currently in a rather crowded resort marina. I think I'll pick a day when I have a smaller audience for a potential electrical fire.

[MadHatter53]

I did the bypass on a different boat I owned and ended up letting all the smoke out of multiple wires and luckily tripped the breaker before the fire extinguisher was used.

[SeaEric]

I by passed the fan rheostat. No sparks, no smoke, but the fans don't run any faster. In looking at the wiring to the fans, there seems to be a small capacitor in the mix. It's about 1 1/2" long by 1/2" cylindrical. One fan motor almost has some legible writing on it as far as manufacturer and specs. I may tear into this a little further before I pull the trigger on a replacement self contained unit. As always, any wisdom from the collective is welcome.

[Captain Ralph]

It doesn't really crank up like it should.
When did it really crank up as it should?
All filters clean? Front evaporator clean?

[SeaEric]

When did it really crank up as it should?
All filters clean? Front evaporator clean?

It ran fine earlier this season. We typically didn't change fan speed and when we did (with the old 3 click version) it suddenly seemed not to be changing which let me to believe it was the fan control. Must be some other issue. Filters and such all seems to be ok. I will say that the fan blades have a crust on them which would impede air movement, but shouldn't affect the speed they turn.

[cww]

Eric, I’ve had a ton of boats with these 3 knob cruisair controls over the years, hell everybody has. They don’t really change the fan speed much when working 100% perfectly. It’s like a 10-20% difference at best. I’m pretty sure that’s intentional. If they’re old enough to have that switch it’s an orifice tube system that predated the use of expansion valves, they have to have a decent minimum fan speed to avoid icing. Or maybe it was just a bad designed switch. But either way none I’ve had have ever made more than a token difference on fan speed. Just enough to barely hear a change in pitch of the whine of the motor, that’s about it. The newer controls make a big big difference in fan speed adjustment.

[SeaEric]

My current problem is that the fan is not running fast enough to prevent icing.

[cww]

My current problem is that the fan is not running fast enough to prevent icing.

Grab a small jug of r22 off ebay and a manifold set and top it off. I have a leaky one on my Chris craft I have to do that with every season.

[rsmith]

I carry several small box fans just Incase I have a fan drop dead when we’re in the Bahamas prop one infront of the vent works like a charm until you get parts

[SeaEric]

I carry several small box fans just Incase I have a fan drop dead when we’re in the Bahamas prop one infront of the vent works like a charm until you get parts

Precisely what I plan to do!