Dear Dave,
I have a Norcold absorption refrigerator. Sometimes when I turn it on to get ready to go on a trip, even when I’m trying to run it on AC power, it’ll keep telling me that there’s an issue with the propane. Eventually, after turning it on and off up to 15 times, it’ll finally start working. The last two times that it did that I was washing the coach and I may have gotten some water down the exhaust on the roof. Today when I tried to start it, it did the same thing again, and it was raining pretty good. Any idea what the problem could be? Any thoughts would be appreciated. Thank you. —Michael, 2018 Winnebago Vista
Dear Michael,
If it runs fine on 120-volt power, that means it is isolated to the LP function and not the control panel, cooling unit, or thermistor.
How the refrigerator runs in LP mode
When the unit is set to the LP mode and temperature set at the eyebrow board, the thermistor inside the unit senses temperature and sends power to the control module to start the process. The LP valve is opened and the spark ignitor (piezo) attempts to ignite and create a flame. If the burner assembly is dirty, the LP flow will be restricted. So I would start by blowing out the supply tube and the burner assembly.
I like to use a blow gun with a 1/4” hose connected to the end, as the flexible hose can get into the tight areas. Make sure you wear safety glasses, as soot can fly everywhere.
Verify you are getting a spark coming from the metal probe of the spark igniter. If there is a hairline crack in the ceramic insulation, it will follow the crack to ground and not ignite. I have found times that the crack was hairline and after several attempts, the heat created made the gap close enough to get a spark to light. (I call them “gremlins”!)
Check the LP pressure
Next, I would suggest checking the LP pressure and make sure nothing else is trying to run on LP such as the water heater or furnace. The best way to test pressure is using a water column tester at a dealership. However, a quick test is to light one of the stove top burners, let it sit for a short time, then light another. If the flame of the first one drops significantly, your regulator might be getting weak. After several attempts by your spark igniter, there might be enough flow to start the refrigerator—another gremlin.
The next step is to verify if the flame does start at the burner assembly and then goes out. If there is no flame, it is downstream of the thermocouple. This is a device that verifies there is a flame and keeps the gas valve open. If it does not sense a flame, or is weak, it will shut off the gas so there is not a buildup of LP in the burner assembly.
Verifying these steps should help isolate where the failure is occurring and hopefully get the unit running quickly. Most of the time, it is a dirty or blocked supply tube and burner assembly, which is an inexpensive fix.
You might also enjoy these posts from Dave
- My refrigerator has excess frost. Someone suggested using a roll of toilet paper?
- Does anyone offer an LP/120-volt RV refrigerator anymore?
- Where to find replacement thermistor for old RV refrigerator
- My RV refrigerator will not run on LP. Should I put in bigger batteries?
- RV refrigerator does not work, but there are no error codes
DAVE HAS ANSWERED MORE THAN 1,000 readers’ maintenance and repair questions. Read a directory here. There is so much to learn!
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
HAVE A QUESTION FOR DAVE?
Send your inquiries to him using the form below.
RVDT2929
I had a Dometic fridge in my 1st TT and the A/C tech could not figure out why the fridge would work on propane. Dometic just wanted us to replace it with their smart ass answer.
My Norcold was doing the same thing recently. I removed the small metal shroud around the igniter assembly and found the burner tube was very rusted. Once I replaced the burner tube and igniter it lights the first time every time.
Whenever I start my fridge before a trip, I first light a stove burner and turn it off to get the propane there. That often takes a bit. Then I run the furnace. Last I turn on the fridge, which is at the end of the propane line.
May have air in propane line.
light a stove burner and let it burn for a bit.
Always works for me.
Have a Dometic here.
No matter how well sealed your propane lines and the valves in appliances might be, eventually residual propane will escape. It is why you should always close the cylinder valves when not in use. After storing the RV there is always air in the lines. 1st thing I do before a trip is to purge the lines.
Start with the stove and use a butane match. When the valve is in the light position, light the match and keep it near the burner. While you can hear something coming through the burner right away, it is likely air. It might take a minute or two for the propane to purge the line and the stove to light. Next I get the water heater to light (make sure there is water in the tank). At this point, our frig usually has no problem running off propane.
Thank you for the trouble-shooting list, Dave. Hopefully, clearing soot is all that is needed. Have a great day and safe travels!