Propex install with stock Dometic fridge

[coastdog]

Has anyone who has installed a propex (2000) and has a funtioning stock Dometic fridge noticed that the LED light on the stove/sink cabinet control panel that indicates that the fridge is running on propane dims when the propex is using propane? It sometimes looks like the fridge has gone out but when the propex stops the fridge light comes full bright again.

It is my understanding that the brightness of this LED light indicates the intensity of the propane flame in the fridge burner box and so it's cooling capability would be reduced as a result. It would seem that the propex is stealing pressure from the fridge. The stove burners are unaffected...
Any guidance would be great.

[b00t]

Its also a very weak system based on the sensor for the pilot light. Could be leaking electricity?

[westyventures]

I would start by checking the regulator pressure with one appliance running. It should carry 11" water-column pressure during the test. If it is low, remove the dust cap over the regulator adjustment. If it is out of spec and won't adjust into spec, replace.

[DLJ]

What Westy ventures says make sense. You may be experiencing a voltage drop, thus affecting the led brightness. Does the Propex work right ? and if your using the heater it must be cold outside, is refrigerator still working well.
Finally, the LEDs often times are not soldered well to the circuit board causing fluctuations in brightness. Easy to resolder.

[coastdog]

All this for a dim light.... says somthing about me. It turns out it was electrical.

Thanks for the suggestions on here and yes the Propex and the stock Dometic fridge work perfectly. It has been below freezing here for the last week. I'm not actually camping right now, just using the cold weather to test the whole set up.

I firgured it wasn't a propane pressure issue when the stove burners looked normal and the fridge 'pilot' light (bottom left of the inside fridge box) looked normal through the Propex sequence while the LED would dim.

I went through all the wiring and grounds, changed the LED bulb and made sure that the new soldering was good, and the problem went away.

[coastdog]

And thanks very much to DLJ, westyadventures and b00t for the help on here. This site is an incredible resource.

Anther quick question for any of you; although I have the Propex wired through my aux battery fuse panel, I found through experimentation that the propex is finding ground without hooking up the black wire from the Propex to the panel. It will run this way if I hook the red wire to the starter battery too..

I checked and there is continuity from the screws on the Propex case to ground even though the Propex mount is completely insulated from the van body. I also checked to make sure that there is good clearance and no contact where the copper tubing from the Propex passe through the van body floor.

Does this make sense that the Propex is getting ground through the case?

[westyventures]

Please connect the ground per Propex instructions, back-fed ground make cause operational issues and/or fry tracks on the PCB.

Very curious about the vent you have installed over the original rear heater opening - is this an off the shelf item?

[coastdog]

the ground is hooked up as per the instructions. It was just through experimention trying to solve the dimming LED issue that I noticed the propex would run with its ground wire disconnected. LED issue solved, I thnik it was a defective bulb or the soldering was poor.

My question still stands; is it normal that the propex heater body would have ground to the chassis. There is continuity between the propex case screws and the frame of the vehicle. Everything works as advertised and has for some time now (many hours of running) so it isn't causing any PCB issues.

The Propex was installed proffessionally in Richmond BC and I will check to see where the vent cover was obtained. Locally as far as I know. I'll let you know.

[westyventures]

Yes, the heater does share common ground throughout its circuitry but always keep the harness grounded for optimal function. I have seen a few crispy PCB tracks over the years.

[jmranger]

(Restating since you said in another thread that this is still an issue)

A few info on the pilot light circuit:
- the sensor is a temperature one. Its (tiny)voltage output is proportional with how far the temperature is away from absolute zero. Therefore, it always output some voltage.
- the panel amplifies that voltage before feeding the LED
- what prevents the LED from being always ON is that LED only turn visibly on once the voltage it sees is above some threshold voltage, which varies from one LED design to another
- the temperature sensor misses the dedicated ground path it should have had (Weatfalia, why did you do that), and that can't be fixed easily. It is therefore very sensitive to ground connections going slightly bad and to all sources of electrical noise around.

Bottom line:
- your trouble is very likely to be electrical
- given that you have a fair amount of custom electrical in that area, it is also likely not to be easy to track and fix

Sorry...

[coastdog]

Solved finally. Propex was finding a strong ground path through the fridge propane line...wtf. This strong ground was pulling the already weak voltage from the thermocouple down. I put a short piece of certified flexible gas hose in the copper line between the Propex and the regulator and the problem in gone. The LED does not change brightness at all when the Propex comes on. It does still flicker brighter when either the sink pump is turned on or the thermostat controlled fridge fan comes on but very little.

[coastdog]

And thanks jmranger for the info above on the pilot light circuit. very interesting stuff and helped me resolved the issue.

[jmranger]

[jstar89crx]

I believe this is the vent that fits over the stock heater opening.

http://www.reddenmarine.com/sea-dog-337400-1-abs-louvered-vent-10-x-5-black.html
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