Hey there,
I've spent the afternoon diagnosing the fridge and have found the following useful summary which I hope may help others;
T6 Ocean Fridge Diagnostic Summary
Unit: Waeco/Danfoss passive convection, 9 years old, ~5 years continuous use, no evaporator fan installed at the factory (pins F and + are empty in the CPT Relay that sits just behind the circular inspection cover in the lower left cupboard and cannot see one anywhere under there, with an inspection camera).
I thought it best to begin monitoring the raw behaviour of the fridge. At the beginning of August, the ambient temperature inside the living area was
31°C. I placed my bluetooth thermometer inside the fridge and strapped it to the bottom of the removable cage so it sat fairly central to the fridge compartment, to be best placed for a general temperature inside. Fridge had been off for 18 hours so was at resting temperature for all components (around
28°C because of it being a VERY warm day).
I needed a diagnostic readout of the fridge's own thermometer. After looking it up, I found this could be seen in the camping control unit by access the Diagnostic menu.
With the Camping control unit on and the screen illuminated, I held down the BACK and SELECT (pushing the wheel inwards) simultaneously for 2 seconds and a secret menu appears.
I chose
Diagnostics then
Hardware List.
Each of the
AN numbers represent a particular sensor that the control unit listens to;
- AN0: Leisure Battery Voltage (Vb Sense)
- This reads the raw voltage coming directly from your rear leisure batteries to calculate the percentage capacity it shows on the main display. This only works properly when the original AGM lead acid batteries are in use. It doesn't calculate properly for LifePo4 lithium cells and should be ignored.
- AN1: Battery Current / Shunt (Amps)
- This measures the rate of electricity flowing in or out of the leisure batteries through the main ground shunt resistor (located under the fridge/wardrobe floor). It determines if the system is charging (+) or discharging (-).
- AN2: External Temperature Sensor
- This receives the data from the outdoor temperature probe (usually located underneath the passenger side wing mirror housing). This isnt a temperature reading, more so a value it uses to calculate temperature.
- AN3: Waste Water Tank Sensor (Grey Water)
- This measures the electrical resistance across the sensor bars inside the waste tank behind the kitchen cupboard to figure out if the tank is full.
- AN4: Fresh Water Tank Sensor
- This reads the resistance values from the probe inside the clean water tank to calculate your fresh water levels (displayed as the 3-bar icon on the main screen).
- AN5: Fridge Temperature Sensor (NTC Thermistor)
- This reads the resistance of the temperature probe mounted inside the fridge box wall. It tells the control unit when to activate or shut off the fridge compressor.
- AN6: Internal Cabin Temperature Sensor
- This reads the built-in temperature sensor located right inside the overhead control unit housing itself to manage climate data. This isnt a temperature reading, more so a value it uses to calculate temperature.
- AN7: Unused / Auxiliary
- On a standard standard T6 California Ocean setup, this channel is typically designated as a spare or empty diagnostic terminal.
- AN8: Roof Position Sensor – Left
- This measures the voltage feedback from the microswitches or sensors monitoring the hydraulic pop-up roof status on the left-hand side. This always show ZERO when the ignition is off.
- AN9: Roof Position Sensor – Right
- This measures the corresponding hydraulic/microswitch sensor feedback for the right-hand side of the pop-up roof. This always shows ZERO when the ignition is off.
What I found:
AN5 was the sensor I needed but it was reading a strange number "79". I later found that this increased in size as temperature goes down inside the fridge. For example, if AN5 read as "101", this would be around
20°C so it does not display a measured temperature, instead a generic value. In this instance "79" meant
28°C.
I turned on the fridge to
level 3 and sat with it for some while. After 3hrs 15 mins, the compressor clicked off and my bluetooth thermometer read
8.4°C.
I immediately changed the fridge to
Level 4 and the compressor turned back on again. I sat with it for another 35 mins until it clicked off. Thermometer read
6.4°C.
I continued upping the level each time and made a note of the temperature inside the fridge as well as the AN5 reading;
Measured cutoffs:
- Level 3 → AN5 118 → 8.4°C
- Level 4 → AN5 123 → 6.4°C
- Level 5 → AN5 128 → 4.4°C
- Level 6 → AN5 133 → 2.4°C
I sat through each of these, and made a brief summary of my findings;
-- Each level increases the AN5 value up by
+5 and drops the compressor cut-off temperature by
−2°C.
-- The Bluetooth thermometer suspended dead-center inside the fridge may be reading around 0.4°C warmer than the fridge sensor near the back so my temperature readings above may actually be 8°C, 6°C, 4°C and 2°C.
-- Camper Control Unit panel and thermostat operation appear to be
normal — compressor cycles correctly at each level but takes a while to reach the temperatures I noted above. This is understandable as it was a warm summers day.
-- As I reached the end of my testing, it was 1am and completely dark so I placed a very bright light inside the fridge to test the lid seal. There was no visible light leakage around the seal so I was reassured this was seemingly still ok.
- Hysteresis (the temperature change that happens before the compressor clicks back on again):
1°C (for example, level 6 turned off when it reached 2.4°C, then restarted when the temperature climbed to 3.4°C, taking 12 minutes to bring it back down to 2.4°C)
Overall Performance:
- temperature Pull-down rate:
~35 min per 2°C on levels 3–5 but took over 3 hours to get from 29°C down to 8.4°C.
- Level 6 took longer (~50 min to 2.4°C)
Again, this was with an ambient living space temperature of around 25°C by late evening. What concerned me was the warm-up rate. When the compressor turned off, it took around 12 minutes to lose 1°C. Thats around
~5°C per hour after compressor stops. The compressor always came on when the temperature climbed 1°C.
What changed:
- Historically, whilst I lived in the van, level 2/3 cycled between
4–8°C.
- Now level 3 targets ~8°C and stays there.
- The long minutes to bring the temperature down points to possible
compressor wear on this 9-year-old unit but I also understand it is also fighting a high ambient temperature.
Summary:
The fridge is fully operational. It fires up the compressor as expected, drops the temperature down over time and turns off when desired temperature (or AN5 reading) is reached. So why do I feel it doesn't behave as I used to experience it?
Likely causes:
1.
Possible Compressor wear — reduced pumping capacity after 9 years, slows the temperature drop (pull-down) using more battery power and running the compressor longer.
2.
Condenser vent blockage — dust/debris collecting on the radiator-style black fins that surround the compressor like a black picket fence, can subtly reduce heat rejection/dissipation efficiency.
3.
Door seal — it passed the light test, but could still be aged in some way?
4.
Fridge plastics still warm - the fridge itself was very warm. The plastics, the glass lid, the metal components below. This will have an impact on initial performance but I do wonder if cooling would become more efficient the longer the fridge is on and allowed to cool all aspects of the food box and contents. I will be posting my thermometer readings over the next 24 hours to see if efficiency has increased, Tomorrow is a 31°C day so will be a real test.
Resolution Steps:
Ive chosen to place a small 12v PC fan behind the water valve handle, in the lower left cupboard, blowing into the cupboard, as a test. Compressor fridges are really efficient and only need a slight movement of air to increase their efficiency by some margin. Because the T6 California Ocean (2017) wasn't installed with a fan of any kind, I've decided this would be a very cheap test to see if the compressor can cool the fridge box faster and therefore cut off sooner, saving battery power.
I'm grateful I installed 200ah of LifePo4 batteries (2 x Renogy 100ah Self Heating Smart) and
300W solar back in 2020 so I'm able to run the fridge near indefinitely for the sake of this test, whilst its sunny. Come winter, however, the efficiency needs to be improved or even the Lithium will eventually be challenged.
I am, however, installing a 3rd 100ah Renogy self heating Smart unit, tomorrow, but only after I've used it to hotwire my roof hydraulics so I can raise the roof and change the Hall Sensors that have died!
With the ignition on, Both
AN8 and
AN9 show
255 which means the sensors are dead. Usually one will show around
108 when the roof is closed, then the values will change places when its open. This means the controller won't open the roof for me as it has no idea what state the roof is in, so I have to apply 12v directly to the motor to get it to buzz open!
Once the hall sensors are replaced, I will be sliding out the Blinds handles on the sides so I can pop the sliding windows and
fit thicker gasket seals. Water ingress is now terrible and this is overdue!
I do love my California.
