Post edited 6:37 am – May 9, 2011 by Steve Pooler

Mike~

The GE relay you describe is the Start Relay that only brings the Start Capacitor into the circuit when the compressor is called for by the thermostat…and It only energizes that Start Cap for a short time.

Yes one side of the reversing valve solenoid coil may connect to that start relay for Line 2 (the bottom left connection that has the most wires to it) That connection terminal post has no internal connection to anything inside the relay…It is only used as a junction terminal.

Your FX-1 digital control makes or breaks the other Line (Line 1) for the reversing valve…so the FX-1 is seeing something to make it send power to the reversing valve…Though it may do this normally when it's thermostat is satisfied (cabin is to temp) to instantly equalize pressures in the system & make ready for the next compressor start…I'm just not that familiar with the FX-1 (as I don't see many) to say exactly how it handles the reversing valve before or during startup.

I will say that the Cruisair controls will energize the reversing valve just prior to compressor start for about a second if the last shutdown was less than 2 minutes ago…If longer than 2 min since last shutdown it will not energize as the system would have had sufficient time to equalize back thru the capillary tubes in the air handler & the reversing valve trick is not needed.

Cruisair, on older SMX controls used to energize the valve for every start but got some complaints about the "Click" noise it makes waking folks that had self contained units under the berth they were sleeping in/on…So they changed the firmware a bit to what I described above.

Little things like this are what make the Cruisair/Marine Air controls a step above the FX-1…But they are also more expensive.

Steve~

Thanks Steve – I'll order that gauge set.

Re the 5-2-1 after reading your response I did some more research – interesting that essentially all the 521 does is what ALL OLD ac units did as delivered – contain a relay/start capacitor.  I'm often surprised how frequently "new," "modern" components of all types are actually "downgrades" from what used to be made and you need to "upgrade" them to be equal to the older stuff.

Ran across a refrigerator from the 1930's that is still running just fine and, according to the owner, has never been serviced.  Our boat needed two new refrigerators (one by the PO) in 9 years. ;)

Steve – turned out to be two related electrical issues

One of the bayonet connections at the compressor was badly corroded and was arcing/making partial contact sometimes.  I cleaned the compressor terminal, cut back the wires to good, clean tinned copper, and installed new connectors.  This resolved the cutting out.  I also put in a new start cap and now the startup surge has dropped from a panel needle indication of 60+ amps to a bit less than 40 A.