Skip to main content ↑ ↓
Topic: Installation of JC Refridgeration 12v compressor unit in Dometic NDR1492 PART 1 (Read 1400 times) previous topic - next topic

Installation of JC Refridgeration 12v compressor unit in Dometic NDR1492 PART 1

NOTE THIS IS PART 1 OF A 2 PART POST

The Dometic NDR 1492 in my 38ft 2004 295 bit the dust after 20 years of pretty trouble free operation.  I replaced the propane/electric heater system with a JC Refrigeration 12v compressor cooling unit. It replaces all the absorption parts and is designed as a direct fit onto the fridge box.

JC Refrigeration makes complete drop in units, gas/electric absorption replacement units and both 12v DC and 120v AC compressor replacement units.  I got the 12v DC compressor unit because it has the advantages of a residential unit (except for auto defrost) and running on 12v means I don't have to go through the inverter.  My fridge is located above the Intellitec light switch controllers and there isn't any residential unit that fits without moving the controllers.  Several folks have moved them as documented on the forum but I decided to go the replacement way to reduce cost and time.  I also like the size and layout of the current box.

The unit cost $1,600 with free shipping.  The controls come preset for 0 degrees in the freezer and 34 degrees in the fridge. I tested it with nothing inside and it got to -2 degrees in the freezer and 35 degrees in the fridge.  The readings are from the display on the control unit.  The factory suggests using a separate freezer and fridge thermometer to verify the temps.

This post is a description of much of what it took to remove the old and install the new unit.  I haven't included step by step of what I did because a very good step by step pictorial installation guide is included that can also be downloaded from their website, Home - JC Refrigeration.  Go to the "DYI Help" page and select the manual for your unit.  Mine is the Dometic SXS 1292 1282 1492 7732 7832 7030 HVAC 12V.  (SXS means side by side).  See Pic 1.

JC Refrigeration offers installation service at their factory in Shipshewana, Indiana for only $200 but after reading the installation manual and having the time and tools, and the help of friends I decided to go for it.  Since I'm at my house in Florida, I wasn't dependent on living in the coach.  The factory says they do the install in 3 hours but that of course doesn't include anything you would normally do to clean and spruce up the box or the installation area.  I took me about 40 hours over 3 weeks with much of the time planning, setting up, cleaning up, repairing and adjusting the old "box" and the installation area. The manual is very good but there are a few things that can be done differently which I will point out.  Before deciding to do an install like this, I suggest you read the installation manual and if not clear on any details, send JC Refrigeration an email or call.  I had the need to send 2 emails before the install and one after and got same day responses.

My unit was in stock and I got it 4 days after ordering. It comes on a wood pallet. The shipper had a small pallet mover and placed the unit where I wanted it near my coach.  See Pic 2.

The new unit comes as one connected whole, weighs about 90lbs with most of the weight at the bottom end with the compressors.  I recommend a helper to get the old gas unit out of the coach and get the new one in and fitted correctly.  The instructions suggest using moving blankets to cover the work area.

Separate from the installation itself, a 12v supply is needed.  The installation manuals recommends a gauge 10 wire be run directly from the batteries with a 20 to 30 amp fuse.  The 12v line that supplied power to the gas units controls cannot be used.  There are no specific instructions since all layouts are different.  I was able to run a wire to the front right hand side of the installation area  floor through the the back of the kitchen cabinets and into the battery area.

The new unit comes with a kit including screws, a control unit, a gas line plug, a freezer temperature sensor (the fridge sensor is built into the control unit), a can of insulating foam, a small role of foil tape to cover the area of foam, and a caulk tube of thermal mastic.

Screws:
Many of the old screws are not used but several are.  I recommend labeling every screw you remove. 

Control unit:
This is mounted inside the fridge section on the lower part of the cooling fins and has two fans, a LED light bar turned on by a motion sensor and displays of the set and current temperature for both the fridge and the freezer sections. The old eyebrow controls, thermocouple sensor and interior light are not connected or used by the new control unit.  See Pic 3.

Gas line plug:
See below for details on how I used the plug differently from the instructions.

Freezer temperature sensor:
The sensor is installed in the freezer via a thin 2 line wire and either screwed into the side of the freezer with a plastic mount or a wire shelf clip on mount.  I used the screw in one because the shelf is not near the recommended spot.  I threaded the thin wire through a small cross section rubber tube to protect it.  I did this after the new unit was installed so I had to slice an opening in the tube to mount it like a split loom. If you decide to do something similar, it would be easier to pass the end of the wire through the tube before it is installed.  The tube was then attached to the freezer side with clear packing tape.  The mount does stick a little out so it interferes with anything put in the freezer near it.  See Pic 4 & 5.

Insulating foam:
The foam is used to seal the gaps between the part of the new unit that fits into the indentation near the top rear of the box that lines up with the cooling fins in the fridge and shelf in the freezer.  Important step as noted in the instructions.  As with these types of expanding foams, it's a little hard to get it right the first time, so I suggest practice a little on a piece of cardboard to get a sense of how fast the foam squirts out and how much it expands.  Rubber gloves a must – very sticky.

Foil tape:
After the foam cures, you can cut off any excess with a razor knife. They give you a small role of foil tape to cover the exposed foam.  See also section below about using foil tape on the back of the box to cover exposed areas.  See Pic 6.

Thermal conducting mastic:
The thermal mastic has the consistency of slippery clay and does not dry.  It gets on your hands very easily and transfers to everything you touch.  I recommend washing your hands frequently to avoid this.  There was ample amount of the mastic in the one tube although you do need to use it liberally to coat all contact points between the new cooling plates and the existing interior pieces that touch them.  The instructions say to put the mastic on the freezer cooling plates before installing.  A dry fit without the mastic is very helpful to see the fit and where the mastic goes.  On my installation, the mastic can be applied to the freezer horizontal cooling plate after it is installed if the ice maker support bracket has been removed.  This prevents the mastic from being scraped off as it is pushed through the slot opening at the back of the freezer.  The dry fit will show the specific details of your set up.  The old mastic that was dry after 20 years needs to be scrapped off before new installation.  I wouldn't recommend the work removing an existing working unit just to replace the old mastic but it did cross my mind that old dried mastic reduces the ability to cool.  See Pic 7.

The details of my experience of course may not relate directly to other installations, especially to other fridge models but the general info and expectation setting should help in any installation.  The entries below describe things I did specific to my installation and that are different or not included in the instructions.

Support frame:
I built a wood frame (made mostly from the pallet) to go on a borrowed heavy duty furniture dolly to be the height of the fridge as it was installed.  This worked out very well since pushing the fridge onto the dolly was pretty easy and I was able to rotate it to get at each spot I needed to work on and have good access within the limited kitchen area.  The factory recommends laying the fridge down on its front during part of the installation but it's not needed and in fact I think its easier if you keep it upright.  Installing the box back worked easily for all but the last 4 inches.  It was stuck at the front end. With a helper we pushed as hard as we could but no go. I ended up using a car jack to take the weight off the front of the fridge and that made the difference.  Constant checking on the movement as seen from the outside through the access area was critical. A helper needed is a must.  See Pic 8 & 9.

Eyebrow controls:
Before removing the fridge I removed the eyebrow with the old controls because it slightly increases the height.  Without the eyebrow, it's still a close fit under the surrounds of the coach's raised ceiling panels but it does fit.  I wanted to try to use one of the old control switches to turn on the extra interior fans I previously wired in via power from the interior light. I was not able to do that so I drilled a hole into the eyebrow panel and installed a rocker switch and indicator light to power on the fans and light.  The original control wires behind the eyebrow include wires to the original inside light that are snaked inside the fridge section.  There are also wires that go to and across the top of the box, then to the back and down to the original 12v supply that powered the eyebrow controls.  I repurposed these wires to get power to the inside light and fans. I also spliced in power to new fans mounted just below the roof vent. Note that the hole at the front top of the box where the wires enter and exit needs to be covered by foil tape or caulk to prevent dirt etc from getting into the eyebrow and potentially into the fridge.  See Pic 10 & 11.

Door removal:
The instructions say to remove the door handles to be hable to lay the box on its front but I removed the freezer door mostly because it was relatively easy to do and it turned out very helpful.  More about this in the cautions section below.

Drain plumbing:
The original plumbing for the freezer and fridge drains, the ice maker water supply line, the 12v eyebrow control power line, and the gas supply line were located in the center of the outside access area near the outside wall.  All of this had to be moved since the new unit's compressors would be in the same area.  See Pic 12.

Re: drain – My coach has a fridge and freezer drain that routes under the floor, between two bays and empties under the coach.  I'm sure a similar set up is on all coaches with fridges that need to be drained.  I measured where the freezer drain is positioned on the back of the box and cut a hole in the fiberglass and plywood floor to fit a horizontal extension to the pex drain line. Be careful if you cut, because there is a bundle of wires directly under the plywood.  Then I trimmed the vertical pex about 2 inches so that it would fit under the floor.  I installed a 90 degree pex connector to the original vertical pex – note the original pex is not clamped in any way and has some free play to move up and down.  Then attached a horizontal piece of pex to move the drain to line up with the freezer drain hole.  Lastly, I installed another 90 degree pex connector and connected it with a new vertical piece. See Pc 13.

Re: ice maker water supply line and12v eyebrow control power line – Both of these are easy to move to the area of the new vertical pex.

Re: gas supply line –The old not used gas supply line is not extended.  The instructions show installing the supplied gas line plug on the end of the unconnected supply line and leaving the line exposed. (The gas was shut off at the tank before removing any of the old gas connections.)  I wanted to cap off the supply as close as possible to the gas tank so I cut back the supply line, crimped the end and pushed it under the fiberglass floor. There are two supply lines from the pressure regulator next to the tank.  One for the fridge and one for the gas cook top.  Since I am still using the gas cook top I had to determine which line was which.  I did the following: disconnected both lines at the regulator and blew air into them which confirmed which line was to the fridge;  put the supplied plug on the fridge line where it left the regulator and labeled the line as not to be used;  bought a plug to close off the regulator end;  reconnected the cook top line.  See Pic 14 & 15.  See Pic 16 in post part 2




Re: Installation of JC Refridgeration 12v unit Dometic NDR1492 PART 2

Reply #1 –
This is Part 2

Floor of installation area:
I removed the fiberglass floor of the installation area and reversed it back to front so the holes for the original plumbing and mounting bolts and 20 years of accumulated dirt and UV discoloration would not be seen.  The floor is glued to a sheet of plywood but it is easily removed by careful use of a putty knife.  Below the plywood is a simple support frame at the four sides and one front of coach to back of coach.  I understand for residential fridges, installers add additional support.  I chose not to because the weight would be about the same.  See Pic 17.

Old and new frame:
The old gas unit included a simple thin metal frame screwed along the bottom / back edge of the fridge with a side piece that went up along the burner stack apparently as an additional heat shield.  The frame is shown in the instructions as left in place but I found this to be not needed.  It rested on two 3"x6" pieces of plywood, that are screwed to the floor.  The frame is then attached to the plywood and the plywood under the fiberglass floor with 2 carriage bolts.  I removed the frame and plywood as not needed and interfering with the new unit and installed two 2"x2" right angle brackets near the back far right and left of the fridge box.  In addition to the 2 carriage bolts, the box is fastened with two screws at the front top (which were not installed on mine) and two screws at the bottom front.  The new unit has a metal frame with all pieces attached to it – verses the old set up of many separate pieces all needing to be screwed to the box.  The bottom of the new unit frame forms a shelf for attachment of the compressors and sits about 1.5 inches above the installation area floor and slightly bows because of the weight. When asked, the factory recommends putting something under the shelf to support it.  I installed pieces of angle iron.  This is not in the instructions.  See Pic 18 & 19.

Screws:
Although I only used a few new screws into the back of the box, it appears you can put short screws into the back of the box in any area under the new cooling plate section.  Of course this only applies to my single experience.

Foil insulation:
After removing all the gas related pieces, I saw that the original foil covered paper that was applied to help insulate had peeled off or discolored because of water damage.  There was some minor rust but all the metal of the box was in good shape so I removed the loose paper and lightly sanded and painted the rusty areas.  I then  applied some 3mm foil faced insulation sheets to the exposed areas with spray contact glue and covered all the corners and curved areas with foil tape.  There wasn't enough foil tape included in the kit so I got another roll before I got to this step.  See Pic 20 & 21.

Edge insulation:
The edges of the front of the box have thin flanges that overlap the wood trim on the sides, top and bottom of the opening.  There was small strips of foam insulation installed to cushion the contact.  These had turned to dust and removed by first vacuuming and then sanding and cleaning up with mineral spirits.  I installed new glue backed rubber tube insulation.  The glue did not hold in all areas because of missed residue so I applied some crazy glue that held it fine.  Note that the bottom flange is a separate piece of metal that is not screwed in but forced under the bottom door hinges and sealed with silicone caulk.  Mine came off as I moved out the box.  See Pic 22.

Ice maker:
The instructions say to remove the ice maker and remove the power connector and water supply because holes need to be made in the new unit to allow them to be reinstalled.  The ice maker is supported by a C shaped aluminum piece that wraps around the ice maker to line up with the new horizontal freezer plates.  I found it to easier to remove the aluminum piece as well to help get the freezer plates to line up.  If you don't want the ice maker, you can just ignore this step.  If you reinstall it, first inspect the troughs where the ice is formed for dirt.  I hadn't used mine in quite a while and the trough area was dirty.  To clean the area, first remove the front cover of the ice maker (just pops off) and then slowly manually rotate the mechanism so that the fingers that move the ice are arranged so you can get access to the area.  The instructions say to measure where the existing holes through the back of the freezer are and then put holes in the new unit base on the measurements.  I found it easier to make the holes after the new unit is installed and then poke the holes by inserting a long screwdriver through the holes inside the freezer.  Be careful to only make a big enough hole to get the wire and water feed tube inserted and don't poke holes anywhere else in the section of the new unit with the refrigerator plates (the large rectangular section covered by aluminum foil at the top of the new unit's frame).  See Pic 23.

Reinstalling the ice maker is a little tricky because the thermo mastic is so slippery.  After reinstalling the control wire, and remounting the C shaped aluminum piece, you screw the ice maker onto it via 4 screws through the bottom of the ice maker. There are two spacer aluminum plates that go between the ice maker body and the C shaped piece. Since they are what transmits the cooling, I first applied mastic to the spacers. That makes it hard to line up the ice maker and the two plates because the mastic allows them to slip.  I applied a small dab of metal to metal glue to the ends of the spacer plates to prevent them from slipping and enable lining up the mounting screws. None of this is in the instructions.

And lastly here are some cautions that I learned the hard way. 

Fit:
Installing the new unit requires the new cooling plates (extensions of the new cooling plumbing) to be slid into slots in the freezer section from the back.  With the freezer door removed, it was much easier for one person to work from the back and one work with easy access to the inside of the freezer. The fridge section has a single plate that just goes flush to the back of the box and is screwed to the cooling fins so fitting it is secondary to the freezer.  There is some cooling plumbing in the freezer that is not directly connected to either the old or new units and is not removed.  It apparently gets cooled by touching the new cooling plates.  I mention this because fitting the new cooling plates into the freezer and reassembling the original metal pieces that cover the cooling plates, form the top part of the freezer, and connect with the ice maker were the most difficult part of the install.  The instructions and pictures are good but you should dry fit them before assembly.  The instructions do say the new unit is made and framed with heavier metal than the original and may be tweaked to fit.  I was not able to twist or otherwise adjust it.  See Pic 24.

Fridge fins:
The fridge section cooling fins are made of aluminum and the edges are sharp.  You need to remove and reinstall them.  There are two sections that fit only one way.  Did I say the edges are sharp?

Wire connectors:
Another caution is the use of Wago wiring connectors.  I hadn't seen them before but upon looking them up I see the pluses and minuses.  They are fast, easy and can be reused but the ones that come with the unit seem not to work well with thin wires.  Specifically the 5 section pieces work fine with the 10 gauge 12v power wires but the much smaller (look to be 20 gauge) control wires not as much.  When I cleaned up the wiring with zip ties, I found the control wires had pulled out. I soldered on a thicker gauge end to secure better in the connector.

There is also a white junction connector (I think are also Wago but not labeled) between the two freezer coil fans and the compressor control unit that failed.  The wires were still in the connector but one of the fans did not work.  I had run the unit before pushing the assembled box back in and they worked but again after cleaning up the wiring with zip ties, the wires to one fan failed.  The wires did not fully pull out but did not make contact.  The only way I knew this was by seeing the fan not turning when I looked down from the vent on the roof.  The problem was that there is very little access to the connector and fan wiring after pushing the box in.  The factory confirmed both fans need to be working. Only way to confirm after assembling the roof vent is to carefully extend your hand between the inside of the outer wall and the condenser fins to feel them.  I had to carefully cut some insulation and fiberglass sheet inside the outer wall to get access and then carefully remove the connector and solder on a new wire to fit. This took several hours.  Other setups with fridges in slides might have an upper wall vent with easier access to the connector.  See Pic 25.

Handling of old frame:
The old unit seems to have failed near the bottom where yellow sodium chromate came out.  Note that this is toxic.  This failure isolated the ammonia in the upper parts and did not vent.  After removing the old unit from the coach, I started to cut it up to smaller pieces.  The local garbage collection would not take the unit as one piece and asked I break it up.  Of course, as I cut it, the trapped ammonia was breached and quickly vented. I stepped back and was not harmed. So the lesson is clear that these units are dangerous and must be handled as such.

All in all it was a doable project that kept me challenged.

Re: Installation of JC Refridgeration 12v compressor unit in Dometic NDR1492 PART 1

Reply #2 –
Larry.
Beautiful write up.  With all the time and effort would you still do this at home or make the trip to beautiful Shipshewanna(lots to do around there) and have them do it for $200?

Re: Installation of JC Refridgeration 12v compressor unit in Dometic NDR1492 PART 1

Reply #3 –
Thanks!  I really considered going to Shipshewanna, but it's a long ride and have a lot of other things on my plate.  Don't we all?

I'm sure they would have done a good job, but as I said, there was a clean up and fix up that only I would do,  like moving the drain connection and sanding / painting the rusted areas on the box.    Small thing - they charge $200 but they save the cost of shipping.  So in the range of $150-$170 an hour for a 3 hour job. 

Something I didn't mention - maybe it's just 20+ years of technological improvement but the the compressor set up is much simpler and cleaner than the gas set up.  Only a few wires compared to the spaghetti mess, and no maintenance other than blowing out the dust once a year.  I guess everyone who converts to residential already knows that, but it didn't hit me until I was done.

Re: Installation of JC Refridgeration 12v compressor unit in Dometic NDR1492 PART 1

Reply #4 –
Larry,
Fantastic post... You put a lot of thought into the work you did and the posting of the information!

It looks like your post is very recent... I'm not on my computer and using my phone to access the forum. Basically, I hope you get my response.

Our absorption Dometic NDR 1062 has failed recently. So I am considering the JC system, undecided whether to go elec or absorption unit. Not sure if our 1200w rooftop solar and 400amp hours of Battleborn batteries is enough for elec conversion. Other consideration is that we loved how quiet our absorption refrigerator was.

What is your experience with sound coming from the elec conversion you installed?

Thanks!

Re: Installation of JC Refridgeration 12v compressor unit in Dometic NDR1492 PART 1

Reply #5 –
Mike, the JC unit compressor is practically noiseless.

J

Re: Installation of JC Refridgeration 12v compressor unit in Dometic NDR1492 PART 1

Reply #6 –
Agree , no sound issue.
There is just a faint sound but nothing worth noting. The compressors just hum a little which is not heard much inside the coach.  The fans that come with the unit (2 on the control box inside the fridge, 1 large one under the bottom set of coils and 2 smaller ones under the top set of coils) all seem to be good quality and are not noisy.  I added more fans with the gas unit both inside and just under the top vent and kept them.  Can't hear them either.
 

Re: Installation of JC Refridgeration 12v compressor unit in Dometic NDR1492 PART 1

Reply #7 –
Quote
undecided whether to go elec or absorption unit. Not sure if our 1200w rooftop solar and 400amp hours of Battleborn batteries is enough for elec conversion

I have 3 Lifeline 8D AGM's each with 225 amp hours and didn't give the power requirement a thought although we do a minimum of boondocking and haven't given the fridge a real test yet.