Dometic 3850870019 Thermofuse, Thermal Fuse, Limit Switch Test

The Dometic recall and subsequent standard equipment solution to fires is called by many names, the Dometic 3850870019, Thermofuse, Thermal Fuse, or Limit Switch. This page teaches what this switch does using a video applying the scientific method.

Is there more than one way to solve the boiler overheating issues with Dometic RV fridge?

Case study showing Dometic solution to the RV refrigerator fire issue, are you safe with this so called safety band aid?

The right way and the wrong way!

It has been reported by many of our customers over the years that Dometic claims that their "containment system" and "thermofuse (or thermal fuse)" switch does the same thing as the Fridge Defend, that is, protect your fridge from failure and in turn help prevent fire. This page is a fact finding test, the Fridge Defend is protected by patent. Dometic has not licensed our innovation, thus they cannot make this claim.

Further, the scientific method requires repeatable tests, the tests in this video are easily repeatable for fact. We are here to help folks prevent fridge failure and fires by the right use of reason.

Quotes from Dometic - Vague, Ambiguous, or Misleading Phrases

Advertisers use them to imply effectiveness without making a legally binding guarantee.

Brown font - quotes from Dometic:

In August of 2020 one of our customers called Dometic regarding the Fridge Defend. When the customer stated "I'm thinking of getting one of those Fridge Defend devices", Dometic employee stated "We have a, what is called a thermofuse on the back, so if the refrigerator does get too hot...it is the same thing that this device [Fridge Defend] would do." We will video test the Dometic thermofuse, and then you can decide if the Dometic thermofuse "is the same thing" as the Fridge Defend?

Default1 Fridge Defend Set-Point ~422°F (217°C) - Boiler Steel Strongest
Dometic Set-Point @ 54°F2 ~1508°F (820°C) - Boiler Steel Not Safe
Video Length: 1:08 (minutes:seconds)
Actual Test Length: 19:33
Sample Rate 1 second
Dometic Thermofuse Outside Insulated Boiler Housing Fridge Defend Monitoring Actual Boiler Temperature
Dometic "thermofuse is a non replaceable component"..."cooling unit will have to be replaced."3 Fridge Defend turns off heat to prevent damage, will automatically restart when safe

Results from Dometic Thermofuse in Graphical Format

Test Dometic thermal fuse using open science an repeatable technique, where data collection recorded temperature sensors at the Dometic thermal fuse and at the actual boiler to show the facts.

The plot or curve is the results from the test seen in the video. The horizontal axis is read from sensor (D) seen in the picture below. The vertical axis is the senor (B) on the boiler tube which reflects the temperature that the Fridge Defend will use to control the fridge.

How did Dometic thermal fuse get tested using repeatable results?

concise (do not use image of or picture of statement) 1-2 sentence description (Keep it under 125 characters) read by screen readers

Open Science Declaration

A) We opened a small gap in the electric heater access door to show the electric heater turning red hot.
B) A precision temperature sensor was attached to the boiler tube.
C) The boiler tube temperature sensor is data logged by the meter on the left.
D) A precision temperature sensor is placed between the boiler housing and the Dometic thermal switch.
E) The Dometic part number 3850870019 recall4 thermal switch set-point temperature is data logged by the meter on the right.
F) A blue LED simulates the refrigerator power through the thermal switch, when the blue LED turns off, the Dometic fridge turns off. This test was conducted with an absorption refrigerator boiler that did not have any fluids nor pressure in it. We attempted to test the Dometic boiler housing thermal switch on a working fridge, but we reached temperatures that were unsafe to continue testing. Thus, we had to use a boiler that was not pressurized for our own safety.

Dometic NHTSA Recall Campaign 06E-076 — 936,866 Refrigerators & Standard Equipment

The NHTSA recall campaign caused a lot of folks to be upset due to unnecessary fridge failures. The below fridge were recalled for the years 1997 to 2007, this recall was standard equipment 2007 and on. This recall in a nut shell was a shield to contain the fire, and a thermal fuse combined with the boiler housing thermal fuse (thermofuse) seen in the video above, click here to read about the recall.

Dometic 6 Cubic Foot RV Fridge

RM2652 RM2662 RM2663
DM2652 DM2662 DM2663
DM2672 DM2682 RM2607
RM2607 RM2611 RM2612
RM2620 RM3604 RM3607
RM3662 RM3663

Dometic 7 Cubic Foot RV Fridge

RM3762 RM3762RB RM3762RBIMF
RM3762LSS DMR702 DMR702LB
DMR702RB DMC702 DMR702LB

Dometic 8 & 10 Cubic Foot RV Fridge

RM2811 RM2812 RM2820
RM2811 RM2812 RM2820
RM2852 DM2852 DM2862
RM3862 RM3962 RM3972
NDR1062 NDM1062 NMH1072
RM 10.5 RMD 10.5T RMD 10.5XT

Dometic 12 & 14 Cubic Foot RV Fridge

RM1350 RM1350M RM1350IM
RM1350WIM RME1350 NDA1402
NDA1402 NDR1402 NDA1402


NOTES:

1) We use the term "default turns off at 422°F" simply because the Fridge Defend can be tuned for either a Dometic, Norcold, or Amish cooling unit fridge. This will change the temperature that the Fridge Defend turns off a particular fridge heat source.

2) Although the Fridge Defend is designed to prevent damage to your refrigerator, when installed and maintained properly, the Fridge Defend will prevent the boiler temperature from ever reaching the high temperature that would trigger the Dometic boiler housing Limit Switch. We do not recommend the removal of the Dometic device unless unless you cannot get a replacement, they are not dependable.

3) Dometic Service Manual RM 3762 & RM 3962, page 15, section 5.12 Thermofuse (3312124.000 10/07, 2007)

4) The Domitic kit started its life as a recall for most Dometic refrigerators as a result of fire issues.  It comes as standard equipment on newer Dometic refrigerators, but is still the same as the recall.