Dometic 1402 Fridge ChLp Error on LP

[Gyrophoenix]

Never had a problem with the fridge until a few days ago. Could switch between electric and LP seamlessly. Tried to switch to the LP, and a few minutes later the ChLp error starts to flash.

I read that rebooting "turning the fridge off" a few times may clear it up. No joy. Tried it a few dozen times.

I can clearly hear the igniter clicking, so it's not an ignition problem. The LP isn't starting to flow.
(Unless the igniter isn't actually sparking, and I'm hearing a mechanical clicking. But if that was the case, I'd think I'd smell the gas after 15 or 20 seconds, and I don't smell any gas.)

Luckily the fridge works fine on electric, but I need to get this corrected.

Any suggestions?

Thanks.

 

[Kirk]

A CHLP error on a Dometic fridge (often seen on models like the NDA 1402 or similar absorption units) indicates a gas ignition or burner fault. It typically means the burner lights briefly but fails to stay lit, or the ignition system cannot maintain a flame.

I found this with a Google search and it fits for the description of your symptoms. If you hear the snap sound it is most likely sparking so it could be a failure to supply gas as with a bad valve or an air/gas mix problem. I would start by applying a shop vac to the burner area first to clean any dirt of bug nests out and try again. It could be a spark probe but those seldom fail on most refrigerators in my experience. If you have a helper, you could monitor the gas valve with a meter to see if it is getting 12V and you could also use the ohm scale to be sure that the coil is not open.

 

[Gyrophoenix]

Kirk, your reply is right on target. I fixed the issue a few hours ago, but hadn't yet posted "the rest of the story."

The burner area did indeed have a large accumulation of dirt, so it was vacuumed out. And that was all it took. Life is back to normal again.

Thanks for the reply.

 

[Crik Walker]

Good morning Kirk, could you explain briefly how to understand ohms, what they are, what function does resistance play in a cuicut, what does the ohms scale tell you etc?
I find all things electrical a challenge and your previous replies were very helpful.

 

[Larry N.]

I'm not Kirk, but ohms is the term for a measurement of resistance, i.e. one ohm is one unit of resistance.

If you think of an electric system as a flow of water (often a good analogy), then pinching the hose is the equivalent of resistance, with how hard you pinch being analogous to how many ohms of resistance.

what function does resistance play in a cuicut,

This is more complex, and a full understanding would likely require a course in electronics, but to way oversimplify, resistance helps control how much current (water) flows, while voltage is analogous to water pressure.

The ohms scale just tells you how much resistance you are measuring, but the measurement must be taken when NO power is applied to the relevant circuit, else you might damage the meter and you CERTAINLY would mess up the measurement.

Hope this helps.

 

[Crik Walker]

It sure does, thanks for this Larry. I'm sure I can make my little trailers electrical system more efficient. We've both grown from a no frills 50Ah FLA trailer to, at present, 200Ah LiFePO4 batteries, maintained w 400W solar, a PD 9345 Converter/charger, 2000W Inverter tied into an auto transfer switch....and I'm now just starting to add fuses, lol. Who knew?
Still have all 10 digits, although admittedly there have been sparks.
Your suggestion of a course r two in basic electronics is a good one, there's tons of stuff online/YouTube etc. Kinda the cart before the horse approach but hey!, yer never to old to learn.
Thx again.

 

[John From Detroit]

Good morning Kirk, could you explain briefly how to understand ohms, what they are, what function does resistance play in a cuicut, what does the ohms scale tell you etc?

As someone said the OHMS scale tells you how much resistance is between the leads.
For RV work you are only interested in "A whole lot" (open circuit)_ or a tiny amount. Depending on the circuit even 0.1 OHM is a lot. (not a whole lot) numbers in the 1-2-3 range depending on the current haul. If you are testing a DC motor or a light then you will get higher numbers but without the spec sheet it's hard to say "good or Bad" Mostly you won't use it.

What is it's function Well imagine a water hose (Length of wire) with water flowing freely.
Now pinch or kink the hose.. that's resistance, as you can see the flow of water is reduced.

Same in a circuit.. The resistor "Reduces" the flow of electrons (electricity) So why do we want to do that? Let's say I have a device that draws 1 amp at six volts.. but the RV's system is 13.6 Let's truncate to 13.. 13-6 = 7 so a 7-ohm resistor will drop 7 volts at one amp leaving six for the device and 7 watts of heat to get rid of (Oh by the way an electric heater is just a big resistor).

Another use some devices store a lot of "ZAP" (We call them Caps, Condensers or Capacitors) A high value resistor will "Bleed" that voltage off before (hopefully) You bleed it off with a errant finger poking around.

And there is more but that's more of interest to engineers and electreonics types

Just like you may wish to slow the flow of water (A valve partially open.. Yup Resistor)
often we want to limit the flow of power.

Does that help?

 

[Crik Walker]

Well I continue to learn on this, the best forum out there. The garden hose analogy is really helpful, thanks for your time and consideration here.
Practically speaking then, resistance isn't a big concern unless I happen to demand higher amps from undersized wires. See my previous "Wiring e-jack into breakaway wiring". Whoops, egg on my face there.
Larry mentioned I could damage my clamp multimeter messing with this unit of measure so for now I'm gonna "look but don't touch".
Take care everyone.

 

[John From Detroit]

Well I continue to learn on this, the best forum out there. The garden hose analogy is really helpful, thanks for your time and consideration here.

When I was in college electrical folks had to study hydraulics and that's where it came from
Electronics Tech types (me) did not get the hydraulics class but electrical did.. Water (All fluids) and electricty behave in much the same manner when they flow. I learned that... Anyway.

 

[Larry N.]

Larry mentioned I could damage my clamp multimeter messing with this unit of measure so for now I'm gonna "look but don't touch".

Actually, I didn't mention that. I didn't mention clamp at all since you don't clamp on for ohms, nor did I realize you were thinking clamp on. What I said was, "but the measurement must be taken when NO power is applied to the relevant circuit, else you might damage the meter." Clamp on is for current measurement (amps).

When measuring resistance (ohms) you use the two test leads (positive and negative), measuring the resistance between the two points where your leads touch. The potential damage is if there is power on the section you're measuring because it may well be too much for the very sensitive circuitry in the meter in the ohms mode. If power is removed there won't be damage.

 

[Crik Walker]

I use my clamp meter all the time to compare amperage flow on my DC House hall sensor. I should have clarified this multi meter has 15 settings, including ohms.
So I have a variety of cables on hand, leftovers mostly. If I measure the ohms on ~equal lengths of 4/0 & #4 welding leads I will see quite a difference. This is handy to indicate efficiency really. I've retired from the welding/Ironworker trade so I've over-killed battery/Inverter connections when practical, 3/0 cable.
I have settled on 200Ah storage/30A solar for my needs, as it's a 30A service travel trailer.
If I can return to my E-Jack situation, the factory connect wires are thin, yet it pulls 11A. Their short tho, maybe 2' long, so I will connect them to my lithium battery via very short #4 fine strand welding leads. If it continues to under function (its very slow, very little torque) I'll conclude it's just worn out and I'll use my drill to drive it.
And if wish to check ohms on the trailer wiring I will make darn sure the battery master disconnect switch in OFF.
Enjoy yer day eh.

 

[Kirk]

If you think of an electric system as a flow of water (often a good analogy), then pinching the hose is the equivalent of resistance, with how hard you pinch being analogous to how many ohms of resistance.

When I was nuclear power electric plant operator in the submarine service, I used to teach basic electrical principles to the mechanical type guys using that very example. To continue the same basis, when you measure the amps you are doing the same thing as gallons per minute through your hose. And, just as with water through a hose, the longer the wire (or hose) the more the pressure drops and eclectic pressure is measured in volts. So the wire diameter has a similar affect to the diameter of a hose does for water. Smaller restricts the flow but if you don't need many amps then a small wire is fine, especially if the wire length is short.

Practically speaking then, resistance isn't a big concern unless I happen to demand higher amps from undersized wires.

That is true but length is also a factor. In most cases we are only dealing with 12V in the RV world and the current needs are mostly small. Power in electrical work is measured in watts and that is determined by multiplying the amps times the volts. If you know the watts needed and it is a 12V system, divide the watts by 12 and you know the amps.

 

[Crik Walker]

I believe I'm starting to understand the bigger electeical picture so to speak thanks to these discussions. I don't know enough to be dangerous yet but I'm close, lol.
"Dangerous" is the apt word here as I just now am beginning to appreciate the merits of 24V, 48V etc systems. That is to say larger currents using smaller diameter wiring. That's about all I know and realistically who of us weekend warriors need this type of system?
I am going to explore this more tho, I'd like to compare what I've invested in my 12V system to the cost if I'd chosen to go with the equivalent 24/48V etc equipmentfrom the git go. I'm aware my 2 LiFePO4 batteries can be construed to provide 24V but....is there an "inline" gadget that allows my equipment to easily accept for example 24V?
My impression is these higher voltage systems are for off grid cabin/permanent home high amperage demand systems.

 

[Kirk]

...is there an "inline" gadget that allows my equipment to easily accept for example 24V?

No there is not. The reason that RVs have been designed to use the 12V system is because the automotive industry has been using 12V systems for years and by doing that the tow vehicle, or the automotive chassis can supply power to operate the RV appliances and recharge the RV batteries.

Since watts of power is amps times volts, if you double the voltage you cut the amps in half, to supply the same number of watts. But the appliances are designed to operate on a 12V supply so doubling the voltage would destroy the electronics that was designed for 12V. In order to use a 24V or a 48V supply you need to have appliances that were designed to accept those voltages.

 

[Larry N.]

am beginning to appreciate the merits of 24V, 48V etc systems. That is to say larger currents using smaller diameter wiring

Read Kirk's second paragraph, first sentence in the above post. That's NOT larger currents -- for a given amount of power, the higher voltage gives you a SMALLER current, which is why you can use smaller wire ALL ELSE BEING EQUAL, which it often is not. And note the rest of that paragraph, too.

You HAVE to be CAREFUL about making assumptions (ass/u/me) about electricity, as it's NOT intuitive, in spite of the water analogy above, which helps your understanding but misses so many crucial details. There are LOTS of gotchas...

 

[Crik Walker]

Electricity certainly can be dangerous and I've had a few close calls/low voltage zaps in my time. Well said Larry. After going over Kirk's post I realized it always comes down to Amps x Volts=Watts.
I'm left wondering then what is the advantages of using higher voltage systems, my impression after limited reads is they are more efficient.

 

[Kirk]

. I'm left wondering then what is the advantages of using higher voltage systems, my impression after limited reads is they are more efficient.

There is some truth to that, but it isn't that simple. Direct current can be stored in a battery but alternating current cannot. And low voltages can safely use a chassis ground for return, but higher voltages get dangerous. Alternating current voltage/amperage relations can easily be changed with a transformer, but that doesn't work for direct current. The very basics of electricity are pretty simple but as you go farther it gets much more complicated.