Help! E1 code issues.

[Alumitater]

Afternoon, folks.
I am having a problem with the Dometic refrigerator in our 2007 Safari that I am hoping one of you may be able to help diagnose.

The fridge (model number RM3762) has worked fine for the five years we have owned the trailer, but recently began throwing an “E1” code in the digital display on occasion. When it shows this code, it does not cool on either shore power or propane. The manual says this code reflects a “hardware fault in the gas operation system”. Turn the unit off, then on again and it works fine until it decides to throw E1 again.

I took the unit to an authorized repair facility and they performed a diagnostic and concluded the control board needed to be replaced. He just completed that board replacement and the unit seemed to work fine in both AC and DC in his shop (go figure) but when we got on the road it began showing the “E1” code again.

I have kept record of the E1 failures and it does not matter if the unit is on shore power or DC. The unit now throws this code at least once a day. When it shows E1, I cycle the off/on and it works until the E1 gremlin strikes again. Problem is, when it shows E1, the unit is not cooling……and you never know when it is going to throw the code.

Just wondering if any of you have experienced a similar issue and how you may have resolved it. Could this possibly be a converter issue? Scratching my bald head here.

Thanks in advance. Tom

[uncle_bob]

Hi

Purely a guess: It's looking either for the "I'm lit" sensor on the burner or the coil on the gas control valve. One or the other is missing when it goes looking. A loose / broken cable from the control board to the relevant device (or a problem with the device) could be the issue.

Again - only a guess ....

Bob

[ventport]

Does it happen when the gas stove or water heater is working? May be a faulty propane regulator.

[Alumitater]

Originally Posted by ventport

Does it happen when the gas stove or water heater is working? May be a faulty propane regulator.

No....stove/water heater not involved....but thanks for the thought.
Tom

[Alumitater]

Originally Posted by uncle_bob

Hi

Purely a guess: It's looking either for the "I'm lit" sensor on the burner or the coil on the gas control valve. One or the other is missing when it goes looking. A loose / broken cable from the control board to the relevant device (or a problem with the device) could be the issue.

Again - only a guess ....

Bob

Thanks, Bob. As the error occurs with either AC or DC my thought is that might not be the case......if I am thinking correctly? If the error only occurred with propane (DC mode) that would be a good starting place for sure. Appreciate the thought.

Tom

[uncle_bob]

Originally Posted by Alumitater

Thanks, Bob. As the error occurs with either AC or DC my thought is that might not be the case......if I am thinking correctly? If the error only occurred with propane (DC mode) that would be a good starting place for sure. Appreciate the thought.

Tom

Hi

It could easily have a built in self test (BIT) routine that checks for "all is well" before doing anything. Without access to the source code for the firmware, there is no good way to tell. There are indeed a lot of systems that work that way .... ( = I've written a lot of that sort of code).

Bob

[2dabeach]

Tom

I would recommend that you call Dometic's customer support and talk to one of their techs.

[bradt]

I have the same fridge in my 2007 Safari and thankfully it still works ok.
I Looked up the error in the manual as follows:
"E1- Disconnected LP gas valve or hardware fault in the LP gas operation system. The refrigerator may still be operational on 120 VAC."

This at least provides some clues. And a direction to look. Note it says "may" work on 120vac. Since yours does not cool on 120vac or gas when E1 occurs, it could be a connection to a component that is used in both gas and 120vac modes. Guessing perhaps a single temp sensor that would cycle the flame, or 120vac electric heater, on and off.
I would check the wiring connections to various gas related components and those around the boiler. Un plug, clean, and re plug connections. Sometimes the plating is bad on the connector. Sometimes the crimp to the wire is crimped too tightly (pressure too high at the dometic factory) and the stranded wire is crushed and strands break one by one. Also, use small zip ties to stabilize wires so they can't giggle around while on the road.
You're doing the right thing to keep a log. I bet you will find it. Good luck!
Brad

[bradt]

Found this post by rhoward 2012. It points to the internal thermistor that is attached to the fins inside the fresh food section.
Brad

Copy of the post follows:
After encountering identical E1 error codes on my Dometic Fridge (Model RM 3762), I contacted my RV dealer who recognized the issue right away. In my case the E1 error code would appear in both LP and AC modes. The fridge would in fact work normally for about 6 hours or until it reached the set operating temperature and shut off as normal. The problem was that it would not re-start and I would constantly have to manually shut it off and re-start it. This procedure had to be repeated over and over every time the fridge reached operating temp.
My dealer had stated that the issue was with the temperature probe or better known as the "Thermistor". To confirm this, he had me push the wire of the thermister through to the back of the fridge and leave it exposed to the outside air temperature. In doing so, the fridge worked normally but would not shut off as expected and would natually freeze everything over time. However, this confirmed that the E1 error code was an thermister (temp probe) issue. The thermister is located inside the fridge and is attached to the "fins" and the back wall of the fridge. It is wired to the electronic control panel in the back of the fridge. I have replaced the thermister (under warrenty) and have had no issues since. (the thermister I removed was subsequently tested at the dealer and confirmed to be faulty. Hope this helps everyone who I see has had this issue.
Ron

[Alumitater]

Bradt: I had found that very same thread after posting my question....guess I did not "search" quite correctly.....and agree the thermister may be a good candidate for cause of my issues. Found a YouTube where a fellow explained how to test and/or replace and will follow up on that suggestion. Would make sense as I get the error code in both AC and DC modes. Sure appreciate your suggestion. Will post results.
Thanks again to all.
Tom

[Alumitater]

Originally Posted by 2dabeach

Tom

I would recommend that you call Dometic's customer support and talk to one of their techs.

Thanks for responding. I did initially and they recommended replacing the control board...which was done and the problem still remains. Plan on giving them another call Monday to see what they suggest.

Tom

[Alumitater]

My E1 code mystery journey continues.

Did a resistance check on the thermister and it seems to be operating properly.
I thought that was going to be the cause based on the other thread, but no go.

So called Dometic again. After explaining the E1 code was affecting both AC and DC operation, the control board had been replaced and the resistance on the thermister appears correct, the tech suggested the culprit might be the gas solenoid valve. Now I need to find out how to test that. Getting a real education here....and getting expensive too.

Any suggestions appreciated.
Tom

[bradt]

Tom, I suggest you remain suspicious of the thermister. I have had problems w a similar thermister assembly on an ice maker. In my case, the resistance readings looked sort of ok, at least showed it wasn't dead. But finally proved that it didn't change its value according to temperature correctly. Note, the thermister in the fridge is clipped to the fins that get wet w condensation. Perhaps a clue.
Problem in my icemaker was moisture could get inside the thermister housing and it spoiled the way the thermister tracked with temperature changes. I suggest try the experiment of pushing the thermister thru the hole in the back and see if the fridge runs continuously.
The gas solenoid is just a coil of wire, and if the resistance reading looks good, and it turns the gas on and off, that is a good sign of a healthy solenoid. That would be hard to replace too.
Good luck with the mystery! Brad

[uncle_bob]

Hi

The solenoid (if it's being tested) is also on a resistance check. Grab the ohm meter and see if the coil is open (infinite resistance).

If you want to check the thermistor more fully, grab it with your hand. If you warm it up by ten degrees, it should drop by a noticeable amount (say 10 or 15%).

Bob

[Alumitater]

Thanks fellows. Just finished checking the resistance on the gas solenoid, was just about what Dometic said it should be. So cleaned the leads and reconnected. Ran the unit on LP (no shore power) for 5 hours, no issues. Then plugged in shore power...the unit switched over and is running now. Think I'll just let it run a couple of days and see what it does.

And will keep that thermister in mind......would be a beast to push through the rear of the cabinet as it exits in a place you cannot see or reach without pulling the fridge out of the wall.

[dznf0g]

Replace the thermister with this, if necessary. No need to pull the wire. Works well, allows for fine tuning adjustment.

http://www.snip-the-tip.com/cgi-bin/articca.cgi

[Alumitater]

Originally Posted by dznf0g

Replace the thermister with this, if necessary. No need to pull the wire. Works well, allows for fine tuning adjustment.

http://www.snip-the-tip.com/cgi-bin/articca.cgi

Well, the saga continues. Someone had suggested the converter might be sending a dirty signal to the fridge causing the E1 error, so I bypassed the converter by plugging the fridge into an extension cord plugged directly into an outlet...still got E1, so converter apparently not the cause.

Replaced the thermister with the snip-the-tip unit this morning, was hopeful the thermister was the cause. Threw E1 code within 12 hours, so thermister is not the culprit.

Running out of ideas, Dometic was really not offering much guidance after I explained what I have done so far.

Any additional suggestions?

[dmbecke]

You may have tried this but google your issue and see if a non airstream owner had a similar issue

[Alumitater]

Originally Posted by dmbecke

You may have tried this but google your issue and see if a non airstream owner had a similar issue

Thanks, I have done that and most results seem to key on the thermister.
Biggest problem is that the error is intermittent. Kinda wish the darn thing would just break, then we could identify the cause. Thanks for your suggestion.

[bradt]

I know you must be frustrated by now, having checked so many things. A couple more suggestions...

The fridge control board runs on 12vdc. It has to have 12vdc for the fridge to work at all. Even on shore power, 120vac, the fridge still needs 12vdc to operate. This means the 12vdc supply is a common requirement for all the modes of operation. If there were a problem with the 12vdc, the fridge could fail in ether propane or shore power modes.
The 12vdc comes in via connections in the outside access panel. I suggest you disconnect, clean and reconnect those connections. There is a terminal strip with screws that clamp the wires to make connection.

Then the fridge runs, that compartment gets warm. A clue could be that during the long delay as the compartment warms up the connections could be affected.

There is a condensation drain from the pan under the row of fins in the fresh food section. The drain is a 1/2" tube going down from the tray. From the outside access compartment, you can see it going straight down the middle and out to the edge of the access compartment door. The water is supposed to drip out the door. On my 2007 Safari, the original plastic tube became brittle, and disconnected at the top. After a delay, condensation could drip down on various control components, possibly causing a problem. You might check the condition of that drain tube. You can pour water in the tray and see if it comes out.

It is good to suspect the converter, especially if it is an upgraded modern smart converter that includes the desulfation stage of high frequency pulses. Depending on the converter brand, these pulses could begin after a long delay for the house batteries to be finally charged all the way up.

Or as someone else suggested, the converter could be supplying a noisy 12dvc that could cause trouble. It also has a long delay as it heats up before it misbehaves. An experiment here would be to disconnect shore power, set your battery disconnect to "use" and run on batteries. Either run with propane, or use your extension cord to provide power to the 120vac plug that is in the outside compartment.

If you have a spare battery available, disconnect the 12vdc wires from the terminal strip, make some extension wires, and connect them to the battery. It can sit on the ground below the outside fridge compartment. Again, run on either propane or on 120vac with your extension cord.

Another thought, and this has helped me, repeat previous experiments to see if your conclusions are the same. I have had situations where I missed a clue along the way. Repeating the experiments with the experience gained the first time can be helpful.

Think in terms of things that can happen after a delay, rather a totally random intermittent "cosmic ray" event. Something is surely causing the problem, and you will eventually sort it out.

Good luck!