Another Norcold Question-- Fans

[tcolburn]

I have a Norcold 1200LRIM. When it runs on AC power, I can hear the cooling fans in the back cycle on and off. But I never hear the fans run when the unit is running on LP. Anyone know if this is normal behavior? 

--Tim C., Park Forest, IL

[desertdeals69]

They should run on either heat source because the cool is accomplished the same way, only the heat is produced differently.

[dickandlois]

Tim, Think you will find that the fans only run when on AC power. The propane heater box uses a different setup to heat the coils. Yes they are the same, but the electric heaters are warped around the coils. Where the LP heater tube heat passes directly over the tubes in the heater stack to heat the coils.

Rich.

Note! with all the issues regarding fires, I have no information of one starting when the unit was running on LP. There might be some somewhere. It is had to read everything that comes through the internet.

The electric heater coils short out, causing an ark. The ark can puncture the heater tube. then the cooling fluid sprays across the electrical ark and ignites.  The protection circuit update, senses the slightest current spick and shuts down the system.

[wolfe10]

Rich,

While I guess you could fit 120 VAC fans, all I have seen are 12 VDC.  Most were fit aftermarket by the coach maker or owner.  Some are on a switch, some on thermoswitches.

Easy to tell.  Open the back (outside) refrigerator access door and determine if the fans are 12 VDC or 120 VAC. And, then what kind of switch is used.

[dickandlois]

On 5/29/2016 at 11:06 PM, DickandLois said:

Tim, Think you will find that the fans only run when on AC power. The propane heater box uses a different setup to heat the coils. Yes they are the same, but the electric heaters are warped around the coils. Where the LP heater tube heat passes directly over the tubes in the heater stack to heat the coils.

OK Brett ! Think I need to clarify the part about AC power !

The fans OEM or aftermarket for the most part run on 12 volts (When the Refrigerator is running on AC) Theses fans do not run when the refrigerator is running on LP!

Rich.

[wayne77590]

1200 xx Service Manual

[huffypuff]

The 12 volts don't diff from a/c or dc volts but by temperature of 130 degrees on and 115 off.  If the fans don't come on while using propane its more likely that the propane part of the fridge needs service.  

[wolfe10]

Again, no standard way these fans are wired.

Some are temperature controlled (on at a certain temperature, off at lower temperatures).  Others are wired to a switch, so manually controlled.

But, looking up through the outside access door for the refrigerator should tell you very quickly how yours are wired.

[dickandlois]

8 hours ago, huffypuff said:

The 12 volts don't diff from a/c or dc volts but by temperature of 130 degrees on and 115 off.  If the fans don't come on while using propane its more likely that the propane part of the fridge needs service.  

Ray, Regarding the on / off cycle temperatures for the cooling fans. The fan sensor is connected to the Absorber units. The Electric heaters are mounted directly to the absorber.

When the refrigerators are running on LP. A second heating tube runs up through the flame stack and connects to the evaporator at the top of the units, as does the hot side of the absorber.  The evaporator is the common point of the 2 high temperature / pressure side of the system. The condensed coolant then has different return lines to the absorber. Depending on the different designs for different models. Some use a smaller tube connected to the top of the absorber along with a second small tube running from the evaporator to the bottom of the absorber.

The condenser low pressure side not only connects to the High side of the Absorber(That is cool when the refrigerator is running on LP), but also to a small tube that connects to the bottom portion of the absorber. This setup allows for a constant source of coolant to maintain the cycle.

Because, the electric heaters are only at ambient temperature + some residual heat remaining in the coolant after passing through the evaporator. ONLY in the hottest conditions will the sensors reach the 130 deg. turn on point.

This could be a difficult scenario to duplicate. Think if the refrigerator is cooling well on LP that would indicate the LP system is functioning with in specifications.

Rich.

NOTE  ! if you look the LP heater tube on the newer units it has a number of kinks in it - this adds to the total length of the tube. This extra length will lower the input temperature of the evaporator. This setup should also reduce the odds of the fans running on LP.

   

[huffypuff]

7 hours ago, DickandLois said:

Ray, Regarding the on / off cycle temperatures for the cooling fans. The fan sensor is connected to the Absorber units. The Electric heaters are mounted directly to the absorber.

When the refrigerators are running on LP. A second heating tube runs up through the flame stack and connects to the evaporator at the top of the units, as does the hot side of the absorber.  The evaporator is the common point of the 2 high temperature / pressure side of the system. The condensed coolant then has different return lines to the absorber. Depending on the different designs for different models. Some use a smaller tube connected to the top of the absorber along with a second small tube running from the evaporator to the bottom of the absorber.

The condenser low pressure side not only connects to the High side of the Absorber(That is cool when the refrigerator is running on LP), but also to a small tube that connects to the bottom portion of the absorber. This setup allows for a constant source of coolant to maintain the cycle.

Because, the electric heaters are only at ambient temperature + some residual heat remaining in the coolant after passing through the evaporator. ONLY in the hottest conditions will the sensors reach the 130 deg. turn on point.

This could be a difficult scenario to duplicate. Think if the refrigerator is cooling well on LP that would indicate the LP system is functioning with in specifications.

Rich.

NOTE  ! if you look the LP heater tube on the newer units it has a number of kinks in it - this adds to the total length of the tube. This extra length will lower the input temperature of the evaporator. This setup should also reduce the odds of the fans running on LP.

   

Regardless of 120 volts or propane the fans are control by temperature not what source the fridge is using.  One example is Palm Springs, CA is 120 F in the shade today.  Imagine how hot it gets behind the wall and the box on those days.  The fans will turn on weather you are dry camping or not.  I dry camped at Coos Bay, OR last summer (not quite as hot) and the fan did run quite often during the day but not so much at night.  The fridge for us worked quite well as the setting had to be set at six instead of nine.  That is why I recommended service and will not hurt if not serviced in quite some times.   

[tcolburn]

Hi everyone. OP here with an update, and another question. Long story short, it turns out that the fans, which are 12v-powered, DO run when the refririgerator is in LP mode--but only if the unit gets hot enough, which doesn't seem to happen all that often (see below).

Here's what I've done since my post back in May:

Replaced original Norcold circuit board with Dinosaur board. Not much change in fridge behavior except that it's much easier to reset when the unit goes into "no-co" mode.

At the same, I deleted the Norcold "recall device" since it had an intermittent habit of randomly shutting off power to the main board even when the heaters were still cold--and I have an ARP-RV controller installed anyway for overheat protection.

Installed an interior circulation fan (manually switched) which does help to keep the refrigerator section cooler but doesn't prevent the "no-co" mode from occurring when the fridge is trying to cool from startup using LP.

Installed an additional exterior cooling fan (harvested from an old computer) in order to increase airflow to the evaporator. I set it up to be manually switched with the interior fans. Still doesn't prevent "no-co" on LP.

So, I set the ARP device to show the heater temperature. On AC power, it consistently reads 185 C (365 F) and the fridge works great. But on LP, the heater apparently only gets up to 172-174 C (342-345 F).

I am thinking that the LP burner just isn't producing enough heat to make the cooling unit work efficiently enough. Am I on the right track? I've cleaned a bunch of dirt and rust out of the burner area, and the flame looks blue like it should, but maybe there's an adjustment I need to make?

Thanks, everyone, for your advice on this and other topics. And I hope you're having a good time in W. Springfield. Hopefully I can meet some of you in Indy next year.

--Tim C.

[rsbilledwards]

From my recent experiences you are on the right track. I have been through three coaches, Safaris with Norcolds and Dometics.  For the OEMs, it is not always about getting the system to operate efficiently, but to get the work done and assembled, ready for sale. Here is what I found on My Panther a couple days ago and the Z last summer. I pulled the Norcold out of it's cavity to install AWG 4 wiring for the solar install. The Panther has only 13,000 miles on it and is of a 1999 vintage. No miles an lots of time had loaded all the coils and condenser with a fairly significant dust film. There were two fans installed and they were laddened with dust and dirt, cobwebs. The wiring for the fans was abysmal, right through the middle of the air flow of the added cooling fans. In many coaches the construction allows for much of the air to by bass the coils at the top and not go through them. In many cases a baffle is needed to force the air to go where is necessary to create the desired efficiency and cooling. The specified distance between the coils and outer wall is something close to 1/2 inch. When I looked at the fans on the Panther they were directed up ok, but at the bypassing void of the wall and the coil. I subsequently adjusted them and foil taped the wiring to the back of the frige out of the air flow,

 Another thing I did was add to the insulation of the coach wall. The framing of the cabinetry is 3/4 of an inch so this was filled first with a layer of 5/16 foil faced bubble insulation and a 1/2 inch layer of foil faced foam insulation. Believe me the heat transfer from the exterior of the coach to the interior of this cavity is significantly less, which of course aids in the refrigeration working a bit less.

Removing these units is not all that difficult. All of the on units I have played with were held in with eight short 1 inch drywall screws.  Three of them across top under a molding , same on the bottom and two through the floor at the back at the access door. There are a couple electrical connections, a 12 volt ground and positive wire and a 120 AC plugin chord on the control board/black box and a propane source, all right in front of you. That is it. I have pulled them out by myself but two people work best. Build a small table about a half inch shorter/lower than the trim on the frige. Pull it out to sit on this table, slide it, table and all to where you can service it and the reverse to put it back. Put a piece of the thin cutting board/sheet plastic under the feet of the table if it is not on hard tile. It will slide easier and leave no evidence you were there. In some cases the doors need to come off. In that case pay special attention to the possible use of spacers that enhance the fit of the door and their locations

This is also a perfect time to install an ARP for the protection of the frige and yourself. This is a unit that will monitor the potential overheat of the boiler and a potential fire. It will shut down the frige until it is safe to restart.

Bill Edwards

[jleamont]

Bill, on your insulation, did you build a duct to cover over the new insulation or was one already present?

I have heard (not sure how true) but the refrigerator requires a duct to properly direct the heat up to the roof vent. Most coach builders do not install that and just toss all of the heat around behind the unit i.e. up onto the roof vinyl, against exposed insulation and wood which escalates the possibly of fire from so much heat back there.

So basically when you set the unit in the wall there is a duct that it sits into and all of the flammable material is covered over by tin ducting. Just curious, mine didn't have any, I had charred wood.

Tim, sounds like you are on top of it. I am unfamiliar with the product you have installed. Just be careful with those Norcold units, they are very volatile.

[manholt]

All off witch begs the question..."why are coaches still using the NoCold and why are the ones who have them still putting up with all the BS?"

[rsbilledwards]

J,

There is a duct out over the whole top of the unit about 6 inches wide and 24 inches long not tin but good ole plastic. There is also a deflector on top of the boiler tube to aid in dispersing the generated heat. It was the same on the Zanzibar. Subsequently there was no evidence of  heat or charring.

Both units were equipped with dual muffin fans to create a positive air movement placed mid-way in the cavity, pushing thru the condenser coils at the top of the unit. The unit was installed as per spec with the desired clearance between the coils and the upper wall..

No I did not cover the insulation, I did however, as I said earlier, add the ARP with fan control. I did also add two more fans  for the ATP to use if needed and for additional airflow as required.

Carl,  The issues are not an everyday occurrence. Iif they were major changes would occur. Not all of them have issues. My experience has demonstrated this, the primary reason these units have cooling issues, and frankly I am surmising based on "MY" experiences with only several. One of them was a Dometic. There is not adequate air flow behind the units. Maybe the installations are not well thought out by the manufacturer. In the case of the four Safari coaches the likelihood of charred wood is minimal because there is none directly in the path of the boiler tube. I do not believe that the fans are a standard feature on either. I think that they are added by the coach manufacturer.

I might add the Dometic has cooling issues as well and I found the same, identical issue, lack of airflow. Added air and it cooled quite well. Some units preform very well and a few are problematic. Just like Porsche engines, every once in a while come off the assembly line and produce 15% more power than the previous 30, All of them built alike from the same parts inventory, nothing special done and the opposite happens, because it just does. I suppose it could happen to Norcold or Dometic, stuff happens.   All of that said mine work just fine! 

 

Bill Edwards

[tcolburn]

Well, I'm back. I decided to do a better job of cleaning the burner assembly, so I disassembled it (and in the process damaged the gas line between the valve and the burner, so I had to fabricate a new one, but that's another story...) and got a bit more crud out of it. Reinstalled it, and also put in a higher capacity 12V fan. Started up the unit, hoping to be home free. Nice big blue flame, and the temp on the ARP's readout eventually got up to 183 C, close to what I would see when it runs on AC. :-)

But then the temp settled back down to 172 C, just as it would show before when running on LP. I let it run for several hours anyway, and when I came back, I had "no co" flashing on the display again. I don't think it completed an entire cooling cycle before it shut down.  :-(

I spent some quality time this morning reviewing the Norcold Repair Manual (that Wayne had sent a link for--thanks, Wayne!). Next stop: thermistor. I didn't do a full check on it before but I had verified that the resistance does change with temperature, and besides, it seems to do just fine when the refrigerator is running on AC. But I'm going to try disconnecting the thermistor for my next attempt, since the manual says if the thermistor is disconnected, the Cooling Unit Monitoring Control (which is apparently what's shutting off the heater) will not activate, and so the cooling unit might run long enough to make the refrigerator section start to cool. (I have been seeing a temperature drop in the freezer section, by the way, so I know that the thing is working a little bit, a least!) After that, I guess I'll have to pull the fridge out and look at the air ducting and stuff (even though, again, it works just fine under AC operation).

I'm certainly learning more than I ever expected to learn about absorption-cycle refrigerators! DW is being tolerant of this learning process, but I think she wants to tell me just to buy a new cooling unit, or entire refrigerator. However, I am the cheapest guy on my block, and I want to fix it myself if at all possible...

I'll be back when I learn some more, and/or (I hope) when I've found a solution! I appreciate everyone's input and observations, for sure!

--Tim C.

[jleamont]

Tim, this is purely my recommendation from a really bad Norcold experience. Toss it in the trash and replace it with a residential.

Here is a direct replacement that I installed for a fraction of the money it cost to fix my Norcold, once it caught fire I was done, plus it removed over 200 lbs from the coach and 3.3 cuft of more space for your DW to put stuff.

http://www.homedepot.com/p/GE-15-5-cu-ft-Top-Freezer-Refrigerator-in-Black-GTS16GTHBB/205092851?cm_mmc=SEM|THD|google|D29+Appliances&mid=sTd6N3Bwy|dc_mtid_8903tb925190_pcrid_47645853702_pkw__pmt__product_205092851&gclid=CO2XvpeUtc4CFQ9bhgod7EIJXw

Photos are here of the finished product.

 

[manholt]

I will agree with Bill E. and Joe.  If it works keep it, not?  Then replace with a residential of your choice, depending on the amount of space you have!

Carl

[jleamont]

Tim, let me clarify. I don't want to see someone make the mistake I made. Mine was headed down the path you are on, I threw money at it and it worked better for maybe a total of 40 hours of operating time, then leaked and caught fire. 

My gut told me from the start to pull it and  walk away, I didn't follow my senses and it could have cost me my coach, DW and both kids. If it worked perfectly or routine maintenance fixed it I would say beef up the safety devices and run it. Looking back that wasn't one of my better decisions. Just be safe in what you do. I do most of the cooking while traveling, DW still smiles about stocking this refrigerator.

Remember happy wife happy life, so they say. 

[manholt]

Bet it was someone's DW that came out with that saying! 

[jleamont]

9 hours ago, Manholt said:

Bet it was someone's DW that came out with that saying! 

YUP! My father in law had to explain it too me, I was probably 27 at the time.

[tcolburn]

Thanks to everyone on this forum who contributed their thoughts. What an incredible resource this group is! I just wanted to bring some closure to the discussion now that we have finally gotten our system repaired.

Joe's comments about being safe particularly resonated with us. Ultimately, my wife and I decided to get the cooling unit replaced with a Dutch Aire, and we went to JC Refrigeration in Shipshewana, IN to have it installed. As part of the package, we had new electric heaters, new fans, and a new LP burner included. Everything now works as it should--I ran the fridge on LP for over 20 hours and the cooling is just as good as it is on AC. And, yes, the fans do run when it gets warmed up! We now have the peace of mind that the old, rusty, unit is out of our coach, plus we still have the flexibility of using LP when electric power is not available (like for cooling the refrigerator overnight before a trip). 

Hope to meet you guys in person one day! --Tim C.

[jleamont]

Tim, glad to hear you are all fixed up and safe. That's one thing you no longer have to worry about.

happy trails