ARP Refrigerator Protection

Actually, this technology was available to me back in the early 60's. I was working for Schellenger Research Laboratories, on campus at UTEP, and had occasion to fabricate my own precision temperature sensors, and to come up with suitable read-out instruments. The requirement was to precisely measure (to 1/2 degree F accuracy) the temperature at the base of the spark plugs on test engines when running them on a dyno, and on test vehicles.
All that's needed for a sensor are two wires, one iron and the other constantan(with proper insulation and sheath). Just silver-solder the two wires together on the sensor end, and connect the other end to a precision quality dc voltmeter. You'll need to look up the appropriate tables which convert this voltage to temperature. You can even purchase a meter that'll read out in degrees F.
For the subject purpose, a simple circuit with proper components can be used to trigger the cutoff switch at the temperature of your choice. I believe 400 degrees F would work for your RV refrigerator.
Here's a photo of the temperature sensor that I fabricated:

Salvo wrote:
I know all about them. I purchased one of the first ARP units. The algorithm is very simple. Either you have a thermal run-away or you don't. When the flu temperature reaches the max allowable you cut power to the fridge. There's no "if's, & "or's" about it. You cut power. The controller can try to power up the fridge again at a little later time to see if it now operates OK, but that's about the extent of the algorithm.

That is not the extent of the algorithm- if it were, a simple thermal switch would do it, and Dometic would not be trying to get around the patent.
I don't know about cheap RTD sensors, but I do know the one Paul uses is pricey- far more than $15.

Two summer's ago I installed one after watching his demo refer respond to being out of level and how the ARP shut it down and then restarted... unlike the NoCold band aid that often shuts the unit down when there's nothing wrong... revision F or are they up to G?

Hi,

I have the second generation product installed. I'd buy one again in a flash. I no longer agonize about whether the RV is level enough to prevent damage.

2nd generation has a fan control feature. I did not install this as I already have a thermostatically controlled external fan system in place.

I agree with Chris. It MUCH more closely controls boiler temperature to substantially reduce the cumulative effects of overheating/precipitating and clogging of the passages.

Suspect if the absorption refrigerators were developed in today's modern electronic age, they would include such controls.

I have talked extensively with the inventor and used one for diagnosing problems- I'm a big fan. It reacts very quickly, and in my opinion, will extend the life of any absorption refrigerator. The one I use is a first generation with data connection, and it is remarkable to watch the boiler temperature change under different conditions.

Highly recommended.