Riddle me this... (Norcold N180.3)

mytabbys701

First the observation/question (TL;DR)

Is it believable that my fridge, on propane, is not getting enough O2 (oxygen) to burn properly?

Today, when trying to diagnose my N180.3 on propane, the indicator gauge was "in the green" for over two hours and the fridge was only getting warmer (it is hot here).

When I went to the Norcold maintenance manual (under Gas flame appearance), I had to remove the burner box cover to check 1) if the flame was blue (not yellow); 2) constant (not flickering); and 3) centered (not touching the inside of the flue tube). It seemed to pass all three checks (see pict).

With that not appearing to be the problem (bad flame appearance), I went to shutoff the fridge and call it a day, BUT noticed almost immediately that the temp inside the fridge now DROPPED (and it is continuing to drop, now 10 degrees in 20 min). The only thing I can account for the sudden change in behavior is that the cover is off and (perhaps) the inside of the burner box is getting more O2.

  

I am wondering if the tiny access door on the (in diagram above), needs to be open more (mine was totally shut and has been since purchase in 2017).

(before I took off the burner box) The longer story leading up to my question, is that I was having problems getting the flame to stay lit (it would go green, i'd take my hand off the safety valve and the gauge would go "white" (flame out)).

Today, after a couple months and after getting the courage to start digging into this, the flame simply stayed lit the first time (but alas did not cool)!

Folks here said "check for spider webs", "obstructions", etc. which is what led me to opening the burner box to check the flame.

BTW: cooling on AC has been fine in all my troubles since late April. Interestingly, cooling on propane was not a problem in Jan of this year. The only thing that changed between Jan and late April is I had the bottle filled (i.e., disconnect, fill, and reconnect). I thought that might be a problem, but the Alde and stove top have been fine throughout this entire, puzzling, mess.

The burner box and the cover has been the only cause & effect that I have seen which has made a difference.

MuttonChops

mytabbys701 said:
. . .
 

I am wondering if the tiny access door on the (in diagram above), needs to be open more (mine was totally shut and has been since purchase in 2017).

Am WAG answer to your Access Door is, No the Door should not be open or opened more.

Why:
    -  Same section of manual that explains how to view the burner flame, ends with
        'Close the burner box door'
    -  Also this part is named 'access' door, not air flow adjustment vent/door/etc

Expect burner will be more likely to be blown out if the Access Door is open.

Do make sure you are giving the Fridge enough hours to get cool/cold.

Might also review how you set the Gas Flame (temperature).
  My N180 lights easier with the Gas Flame set to the word HIGH (as per manual instructions).
Maybe you are setting the Gas Flame knob above HIGH (it has an even bigger flame symbol then HIGH) and something is not functioning as it should
- - - too much heat, or heat hot spot is in wrong position, or  ? - - -

I've actually never tried or needed to try setting the knob above HIGH.

targ

During all your investigations/bad experiences, has your camper door by any chance been open?  On ours, if the main door is open all the way to the lock position, the fridge will not cool.  There's just not enough airflow through the vents if they are blocked by the door.

Also, you mentioned after two hours it seemed warmer.  That's not nearly long enough to wait.  Ours takes maybe that long for the internal fins to just be barely below ambient.  Getting the fridge actually cool takes a lot longer. 

As a reference, just this weekend we went on an impromptu run.  I started the fridge on AC while getting ready.  It took two hours to drop from 77F to 63F,  I ran it on DC while in transit.  In that hour and a half, it went back up to 69F.

Then, when we got set up and switched it to propane, it took another 12 hours (most of that was actually overnight) to get down to 37F.

ChanW

In my experience with the three-way, the fins won't start getting cool for quite a number of hours (2 hours may not be long enough). 

Also keep in mind that the waste-heat vents need to be unobstructed, ie when the door is open it blocks the waste heat vent. If the wind happens to be going the wrong way it will prevent the heat from leaving. Also, does your three-way auxiliary fan work properly? That helps to expel the waste heat out the vents.

Another thought is mud-dauber wasps in the intake vent. Rumor is that they're attracted to propane systems.

mytabbys701

Hi everyone, thanks for your insight / feedback. I am now repeating my experiment. Today from a fridge & propane that was turned off all night, i have done the following

- re-installed the box/cover access door to its original position
- turned on the propane, flushed a bit with the stove and turned off the stove
- started the fridge on propane on the normal high setting
- started the waste/heat vents (installed a few years ago) and ensured the door is not obstructing the upper and lower vents
- recorded temp/time and will check hour by hour

This is the fridge panel at this hour (that piece of masking tape is my normal operating setting when all of this was working back in Jan)



@MuttonChops: i noticed the same thing a while back - that knob position in the picture is where i start the flame at - like you said, i have much greater success starting in that position that the clock-wise bigger flame icon on the safety valve.

@targ: my terrible memory is failing me again, but i don't recall it every taking that long to start cooling (as opposed to getting to an internal lower operating temp). hence, with your and @ChanW encouragement, that is why I am starting the experiment all over again and just waiting patiently. My waste fans do seem to work great - tissue paper will hold against the lower intake vent when those fans a running - and the air coming out the upper exhaust fans is most certainly warmer than the ambient temp.

@ChanW: when you say "intake vent" - are you speaking of the lower external intake vent (for me which is on the passenger side, of a late 2017 t@b (and higher)? if so, I can say, no daubers there.

i'll post back in about 12 hours to report what i found.

targ

Did you add the waste fans or were they factory?  I *wish* ours had fans - all we get is (pathetic) convection.

mytabbys701

Hi @targ, i did my own "hack" (see https://tab-rv.vanillacommunity.com/discussion/7493/my-norcold-exhaust-fan-hack )

since that time I have improved upon the connector and tweaked it a bit, i am happy to say it has served me very well.

mytabbys701

So the good news is that with everything back together, the fridge appears to be running normally on propane.

The bad news is that I don't like magic. I did nothing to resolve the problem I had back in Apr (lasting over four weeks) when the fridge would not stay lit, and when it did stay lit (yesterday, that was magic trick #1), it did not cool for two hours until I removed the burner box cover when it then started cooling almost immediately (that was magic trick #2).

hour	fridge temp	ambient temp	exhaust temp
0	83.4	84.0	no data
1	76.2	88.3	no data
2	61.5	89.7	~127
3	51.4	91.7	~128
4	45.8	93.7	~127
5	42.9	94.6	~128
6	41.3	94.2	~133

The t@b was in a garage (with garage door open) and not exposed to direct sunlight. The inside of the t@b and the ambient temp of the garage inside were one in the same (in other words, no air conditioning occurring within the t@b). I used an old school indoor/outdoor La Crosse 915 MHz Wireless Temperature Sensor so I did not have to open/close the door to record inside temps. Exhaust temps were recorded with an infrared temp gun

At this point (after 6 full hours), I have ended the experiment.

It was clear on this round that cooling within the fridge did occur within an hour and continued until i turned it off.

But, alas, I have no explanation why all appears better now.

Dudlee

Thanks for the temperature info. My issue has been the Norcold on propane freezing stuff when the outside air is 60-70 degrees. This is with it set on the warmest setting.