Unknown Fault Code on Dometic AC

[GaylesFaerie]

Hi, I've looked in the manual and I can find no documentation of this fault code. Gayle's Faerie is a 2012 R27 Classic with a Dometic Heat Pump. When I turn the unit ON a fault code will appear on the control panel where the first and third symbols are indecipherable and the middle symbol is a 5 or S. I turn the unit OFF. I turn it on again, and the unit shows the ambient air temp in the cabin and begins working. The water temp is about 65 degrees, the seacock is open, and while running a nice steady stream of water is exiting out the port thru hull. The unit will run for about 10-15 minutes pumping out cool air - nothing bone chilling but clearly cool. Then the unit stops and displays the Low Pressure Fault code LPF. I turn the unit OFF. I wait 10 minutes. Then the whole sequence of events will repeat. Any thoughts or ideas appreciated. Pics below. GF

Code on initial start: https://photos.app.goo.gl/7e3Uwg11QCPWiQVBA
Unit running ok: https://photos.app.goo.gl/qutG2Db7LFrPr75e6
LPF code: https://photos.app.goo.gl/zfEg6gnEsxhJkfgW6

 

[ethanbarnett]

Call Webasto 800.860.7866. They have helped is greatly. When I had another problem with unit shutting off with a unique code a local guru asked if I have a spare capacitor to swap out to see if that fixes things. He suggested having a fluctuating power source can cause issues. $15 later, I carry two spares, the ac worked great again. Good luck.

 

[HRowland]

Hi Gary,

That strange code looks like tSt, for self test mode. From the Dometic Elite Panel manual:

AUTOMATED FACTORY SELF-TEST PROGRAM
The Elite software contains a self-test program to facilitate factory testing of the entire air conditioning system. Once the self-test program is activated, the test cycle continues until the AC power is interrupted or the Power button is pressed once, which returns the system to Off Mode.
To activate the self-test program, press the Power button immediately after turning on the AC power and while all LEDs are illuminated (“888”). The control is now in the self-test program and “tSt” appears in the display.

Once activated, the self-test software continuously executes the following commands:
1. Turn on Heat Mode and supply heating for ten minutes.
2. Stop heating and run only the fan for five minutes.
3. Switch to Cool Mode and continue cooling for ten minutes.
4. Stop cooling and run only the fan for five minutes.
5. Return to step one and repeat procedure until interrupted.

To halt the self-test program, press the Power button once or interrupt the flow of AC power.

I don't know why you are getting the LPF, it could be a faulty low pressure switch/wiring or an actual low Freon pressure issue. If the system has leaked Freon it could cause a low pressure fault.

Howard

 

[GaylesFaerie]

Thanks Howard. That makes sense. Looks like Dometic omitted that code from their General and Digital - Controls Troubleshooting tables. I continue to be impressed (and appreciative) of your knowledge of the boat's systems so many years after owning it. I'll try running the Self Test sequence and see if anything interesting pops up that may help with the LPF code. GF