1997 420AC: Cruisair SX7 inactive past SMXii controller

[jeffsuwanee]

I have a 1997 Cruisair sx7 a/c unit (one of three) on my sea ray 420ac cruiser. The unit has an SMXll controller. All three of these unts have been performing flawlessly since I bought the boat in January. This week the forward stateroom unit stopped working.
Symptoms: SMXll controllers lights up and all buttons and function lights are usable. There is no activity at all on the AC unit itself..no compressor, no fan…nothing.
What I've done:
1. Swapped out the smx keypad with another one on the boat…keypad checks out fine.
2. Changed out motherboard inside prologic box…still no activity at AC unit.
3. Put SMX in continuous mode to try to activate fan only….nothing, nada, ziltch.


Next steps????


Thanks in advance,
Jeff

 

[Doug Doty]

Don't forget to try the simple reset procedure on the SMX face that is printed in the manual, it will tell you in trouble shooting, early on the do a " factory Memory Reset" as follows. Simultanously press "OFF/SET/FAN and them immeadiatly press SET again. I have not personally seen this fix an issue yet but a lot of folks here have had this resolve issues. I have read that one of the next steps is to verify 5 volts between pin #1 and pin #4 on the controller connector but yours lighting up and seeming to function unto it's self, I believe gets you past that, I have been studying to fix mine for the past 2 days and mine was the SMX11 and I ordered one of Flight Systems brand new 2 year warranty units that they recently came out with. Price was not objectionable. I don't think they have even put them on their web site yet. They said they are real backed up at this time with reman work and have no pre. remand units to send out in advance of sending in you bad one. I have not yet found in my reading that there is or is not a reset on the main unit but i cannot believe there is not. I would look there next. If you are comfortable doing so you can check voltage on the compressor or fan wires while the SMX says they are being told to run and if they are not they are either bad or lacking voltage and that is the next clue. I bet they are not actually being told to run for some reason, I think you said it would let you tell it to do any function but yet the compressor or fan would not respond ?? When you press the Air Cond. button does it light up saying the compressor is running ?? I was working on mine a few hours ago and know it does when working properly, light comes on, on the top left as the compressor starts. Let us know what you find.