Cruisair SMX lost its mind

[J Levine]

Put the boat in the water today and enjoyed a beautiful ride up the bay from the yard to my slip. We spent the afternoon cleaning and arranging everything for the season. I ran the AC units to check them out and upon turning on the unit in the forward stateroom it immediately went to a temp setting of 99 degrees and kicked on the heat. I turned it on an off a few times and each time it returned to 99 degrees. I then unpluged the control cables to make sure they were tight as I once had a problem 3 years ago with the forward unit that was cured when I simply removed and reinstalled the control cable at the compressor. Nothing worked. I then swapped out the controller with the identical unit in the aft cabin and sure enough the controler had the same effect on the aft cabin unit compressor while the aft cabin controller functioned normally when hooked to the forward compressor. So it appears that somehow over the winter the forward controller, which of course was working perfectly last October, lost its mind. I guess I need to get a new one. Any other thoughts for me?

 

[wkearney99]

Could it be the buttons are stuck? Could've corrosion have developed under them? For it to suddenly crank all the way up to max temp might mean the temp up button is stuck. Might be as simple as pulling the unit apart and cleaning up a few contacts. But with the membrane style keypads that might not be possible (can't usually tell until you get in there).

That and check with the factory or a dealer. Crusair in Annapolis was pretty helpful in answering my questions and fixing a shorted-out main controller (under warranty).

 

[rondds]

i've taken calculators apart b/c a button or two were not making contact when i pressed them. cleaned the foil with a pencil eraser and got them working perfectly again. different type of button compared to your SMX unit and not sure you can even get these things open; but if it's shot and you're gonna chuck it anyway, cant hurt to give it a try.

 

[fc3]

What did you swap? Did you swap the SMX control panel with the buttons and display or the SMX processor which is mounted near the air conditioning unit and connects to both the display (with a thin cable) and the air conditioning (with a thick cable)?

Best regards,
Frank

 

[J Levine]

Frank

I swapped the controller/key pads.

Jon

 

[jtm311]

This may sound stupid but make sure none of your TV or Satellite remote buttons are pressed near the unit. For the longest time I could not figure out why my heat and Temp would go up all on it's own, well it was the Sat remote I little piece of black tap over the controller fix that.

John

 

[fc3]

The buttons are membrane buttons if you have the one with the raised "dots" for buttons. Not serviceable. It's two printed circuit boards. One circuit board is rigid. The other is a flexible plastic. The raised dots flex when pressed, which causes the circuit printed on the flexible part to touch the circuit printed on the rigid part. So far, so good. Right?

After a while, sometimes the circuit printed on the flex part flakes off. No more button pressing. Sometimes the flakes short out the circuit, continuous button pressing! The newer ones are better.

Membrane switch matrix assemblies were hot in the 80s and ran into the early 90s. Then the flaky problem showed up and companies when to the rubber mold with embedded metal contacts, which are much more reliable.

The SMX-ir has remote control capabilities, but that was not available in the 1990s.

Best regards,
Frank

 

[J Levine]

I imagine the thing is fried. Looks like the going price is $205 for the unit. It can be replaced in about 2 minutes. I found a couple of sources on the internet so I am going to make a few call tomorrow morning and give the AMEX number to the first guy that has one in stock.

Considering the $650 I spent taking on 200 gallons of fuel right after I splashed her (at $3.40 a gallon) this gizmo cost less than 2 hours of run time at 3200 RPM and 19 knots. You know "boat dollars". I am glad that I was able to swap the two keypads to rule out any other issues, though considering the AC units are now 13 years old and have never been touched I am sure more fun with AC can't be too far around the corner for me. Getting to the unit in the salon looks like a nightmareish project involving the removal of like 100 stainless steel screws to removed the sourounding cabinetry and such.

 

[J Levine]

Update: I ordered a replacement controler for $205 from Nautical Air yesterday morning and it arrived today. Frank was right, the design has been changed. The original had membrane switches mounted on a separate board that was connected to the main board with a ribbon cable. The new design has switches mounted directly on the main board that are actuated by buttons. It looks much more durable. I wont know if it works until I take it to the boat on Sunday and install it.

 

[skolbe]

I replaced mine on my 260. My down temp button was stuck on. The new one worked great. Good luck.

 

[Kellie]

Most of the buttons are completely sealed. The "up" button has a small hole. To see this you have to peel the buttons off of the sheet metal. You will notice what looks like dirt because of the hole. I used a small plastic tooth pick to clear the "dirt". I really could not get it out of the hole... but it is fungus strings that are completing the circuit... so breaking them will fix it... until it grows back.

 

[Creekwood]

Most of the buttons are completely sealed. The "up" button has a small hole. To see this you have to peel the buttons off of the sheet metal. You will notice what looks like dirt because of the hole. I used a small plastic tooth pick to clear the "dirt". I really could not get it out of the hole... but it is fungus strings that are completing the circuit... so breaking them will fix it... until it grows back.

You are responding to a 9 year old post. (but welcome to CSR anyway!)

 

[370Dancer]

And, Jon sold Corona del Mar a looooong time ago. Thinks he plays golf now. Side effect of a long running (and best source of DIY info) site.....
welcome!