Digital A/C Controls

LHFixer · Post by **LHFixer** » Sat Jul 12, 2008 9:28 pm

I'm looking to change out my old three knob A/C control unit for a computerized one. Has anyone done this conversion?

http://www.cruisair.com/sheets/L-0613A.pdf

It looks all snazzy like this:

http://www.cruisair.com/smx.html

Runs $700 a unit..

They make it sound like all of the functions are dependent on this. Most importantly the dehumidification cycle, apparently. However, I think I could make this with some parts from radio shack and a Honeywell digital thermostat from Lowes...

http://www.lowes.com/lowes/lkn?action=p ... lpage=none

Any insights?

Cheers,

Eric

Stripermann2 · Post by **Stripermann2** » Mon Jul 14, 2008 8:44 am

You can't convert the 3 knob to a digital, at least that is what I have found out through my dealings with Crusair.

The thermostat, is really not a thermostat. The 3 knobs controls temp, fan and compressor operations. A household thermostat will sense temperature and adjust accordingly. The thermostat on your compressor is the bulb or probe on your evaporator coil, which does the sensing. The newer systems are designed to sense water flow, low freon pressures and high pressure conditions as well and shut down unit if neccessary.

The digital systems are different in the unit itself and in the control pad.
These systems work together and are not compatible with older units.

ltbrett · Post by **ltbrett** » Tue Jul 15, 2008 10:40 am

I spoke at length with cruisair when I was considering replacement of my 3 knob system with an SMX II. They sell a kit. Striperman is correct in that you can't just put on a new digital control, you have to change the brain. The kit contains a new black box and a new digital thermostat. I opted to replace the entire unit as mine was 25 years old (still working fine).

Brett

ltbrett · Post by **ltbrett** » Tue Jul 15, 2008 10:47 am

BTW--ask cruisair about the safetys on your current system. There is generally a high pressure shut down, which will trip for low seawater flow and (IIRC) for low freon. That safety will stay intact if you put in a household thermostat, so I suppose you could get away with it. I had a similar thought but decided to do it the right way as I want to leave the a/c on while unattended.

Brett

g36 · Post by **g36** » Tue Jul 15, 2008 4:40 pm

sure you can put a digital control on your system and much cheaper. mine was the 3knob control also.

heres what i put on my f32 last year and has worked perfect took about 15 minutes to wire simple simple. prices may be different but should still be in the ballpark

here is a copy of my post

PostPosted: Sun Dec 16, 2007 11:57 am Post subject: fx 1 Reply with quote Edit/Delete this post
here you go

i replaced my rotary 3 knob contols with this micro air fx-1 retro fit kit
distributor was AER, piece of cake to install.
heres a link to microair
http://www.microair.net/
click products and go to fx-1 retrofit you can see pic of display and also download the manual.

AER prices/parts needed for retro

Part Number: ASY370X02
Description: Power Logic box w/Circuit Board
Net Price Each: $ 148.13

Part Number: ASY390X01
Description: FX1 Display Vertical Black
Net Price Each: $ 164.42

Part Number: SUB031X15
Description: Display Cable 15â€™
Net Price Each: $ 11.25

Part Number: SUB056X07
Description: Air/Water Sensing Cable 7â€™
Net Price Each: $ 12.50