Crusair SMX II Problem

[davidwigler]

The split unit for the salon (two air handlers) is working but both fans won't shut off and only run at low speed. The SMX II controller controls everything else just fine.

I shut the power off at the breaker hoping it might reset the unit but no luck. Any ideas?

[davidwigler]

Does anyone know if the power logic board is the same for the 24,000 BTU unit as it is for the smaller state room units? In other words can I swap one out with the other to diagnose the problem?

[Boatsb]

I may have one to look at. I'll pm tomorrow when I find it.

[PeterK]

I'm having some issues with 2 of my units. My electrician/AC guy checked and the logic boards can be swapped, i.e. they are not made for specific BTU size. I am planning on using the board from the 5K crew cabin in my 24K salon unit.

BTW I called Flight Systems about rebuilding the SMX II board and they want to see it before committing to fix it.

[Boatsb]

It's not the btu. It's the voltage. Unless he has all 110 or 220 I'd be careful.

[PeterK]

Scott, dead on. All my units are 220.

[Boatsb]

I may have a control board for a 220 unit. That's what I'm checking on.

[davidwigler]

"My electrician/AC guy checked and the logic boards can be swapped."

That's exactly what I needed! (All five of mine are 230 volts). Thanks.

What would we do without this site?

[Dan Mapes]

Doesn't the SMX II have a "constant fan" mode? Perhaps it needs to be reprogrammed?

[saltshaker]

Mine all are set to leave the fan running whenever the unit is on. As far as the fans only running at low speed, I've had this happen before when voltage was marginal. Check the voltage at the compressor and the air handlers.