Norcold SCQT repair?

[mashenden]

Originally Posted by azsailor12

I also have a 4407, but fortunately it's working. The Thetford website has some documentation and spare parts list. It appears that all major assemblies are still available.

Thats good news. Hopefully once I overcome the original owner's mistakes on the installation, I hope mine will work for years to come. I really like the design and concept.

Regarding the Thetford site, that was the start of my frustration. The few documents that are available had discrepancies or gaps in information. Not too uncommon, but when I called them for clarification they could not answer my questions, stating that they "did not have a technical support person"... Wow, really???

In calling a couple of dealers, they too expressed frustration and commented that it was hard to price replacement parts for these systems since they are really not intended to be serviced. Grrrrr.

[mashenden]

azsailor12, I do have one question that you may be able to comment on if not too much trouble.

I have a control box from an old Norcold SCQT-6407 which is a predecessor to the 4407/4408 systems. It has a knob to adjust the temp, an ON/OFF slide switch, and one LED - pretty simple. I was hoping it would be compatible, but it has 4 wires into a plug, whereas the one for my 4407 needs 5 wires. I hope to learn why the newer 4407/4408 systems needed the additional wire.

My question is whether your control box has anything more than a knob, switch and LED?

Also, if anyone has a dead 4407/4408, I am in the market for a used control box, as well as a set of male and female quick-connects.

[mashenden]

An interesting breakthrough - I found a Norcold document on-line that includes a wiring diagram for the old SCQT 6407. Bk and Bn wires are to the ON/OFF switch, Yellow and Red connect to the resistors and variable resistor for adjusting the temp.

This document is much better than what I have found for the 4407/4408, which is what I really need.

Still, if I have to guess on mine, I'll at least have this as a means to make a SWAG. It still bothers me that I don't know what the Orange wire does.

[mashenden]

Oh well, the wiring info for the old SCQT 6407 did not get me anywhere.

I was hoping that crossing the Bk and Bn wires would result in the compressor and fan kicking on, but no luck. Apparently the orange wire and/or other wires also need to be connected.

A quote for a thermostat, part # 1601-140-40 for my SCQT-4407 wasn't as outrageous as I had feared so I decided to take a leap of faith and order it from S & S RV Svc Center in Gettysburg, PA (717-334-0149). I hope it works out. I was very impressed with the reviews on S&S - very high praise. They were the only dealer that seemed to be interested in helping me and could find the part to be able to quote it. My impression was very positive.

[ErikFinn]

Originally Posted by mashenden

It is worth the time/effort IMHO given the unit was damaged during its initial installation, meaning the compressor unit has 0 hours.

I realise this thread has been sleeping for 2.5 years but something happened today that made me google "Norcold SCQT-4407".

I visited my little local marine shop today and spotted a Norcold SCQT-4407 on the window. Having had incredibly bad luck getting a boat fridge kit here to the booneys in the past I was naturally interested. I talked with the guy and he told me that he has TWO of those units. Both USED. Both are customer returns under warranty and the other unit only was ever switched on for a day and a night but never produced any cold. His price for the evaporator plate only was 1000 ringgits (about 250 USD) and he would throw in the compressor as well. Norcold do not want these faulty units returned to them, they just ship a new unit to the customer.

At this stage I got really exited and thought to myself omg, I'm gonna snatch that set and fix it up. But then I thought to hold my horses and do a bit research first. And OMG. Google search shows plenty of problems with these units. Not just on this forum but on other ones as well. Or is it just that people only write about disappointments? But it did not appear to be uncommon for these to never work out of box or failing relatively soon, like after a season or two. Are these really so bad? If I paid 1K for a similar kit I would want at least 10 years of service out of it. (Nowadays WM price for the newer 4408 is 700 plus).

Mashenden, were you able to repair your unit? If yes, what did you do? Did you find out what that fifth wire was for?

This question goes to everyone: is it really so that one can not add gas to these? Can not retrofit valves and use a gauge set and vacuum the system? I am no expert but I am under the impression that one should vacuum the system before adding gas?If adding gas is no option then I don't know if these can be made to work after they have been connected and disconnected once. Anyone knows?

Thanks,

Erik

[mashenden]

Originally Posted by ErikFinn

I realise this thread has been sleeping for 2.5 years but something happened today that made me google "Norcold SCQT-4407".

I visited my little local marine shop today and spotted a Norcold SCQT-4407 on the window. Having had incredibly bad luck getting a boat fridge kit here to the booneys in the past I was naturally interested. I talked with the guy and he told me that he has TWO of those units. Both USED. Both are customer returns under warranty and the other unit only was ever switched on for a day and a night but never produced any cold. His price for the evaporator plate only was 1000 ringgits (about 250 USD) and he would throw in the compressor as well. Norcold do not want these faulty units returned to them, they just ship a new unit to the customer.

At this stage I got really exited and thought to myself omg, I'm gonna snatch that set and fix it up. But then I thought to hold my horses and do a bit research first. And OMG. Google search shows plenty of problems with these units. Not just on this forum but on other ones as well. Or is it just that people only write about disappointments? But it did not appear to be uncommon for these to never work out of box or failing relatively soon, like after a season or two. Are these really so bad? If I paid 1K for a similar kit I would want at least 10 years of service out of it. (Nowadays WM price for the newer 4408 is 700 plus).

Mashenden, were you able to repair your unit? If yes, what did you do? Did you find out what that fifth wire was for?

This question goes to everyone: is it really so that one can not add gas to these? Can not retrofit valves and use a gauge set and vacuum the system? I am no expert but I am under the impression that one should vacuum the system before adding gas?If adding gas is no option then I don't know if these can be made to work after they have been connected and disconnected once. Anyone knows?

Thanks,

Erik

Yes, I got mine to work. Mine did not have gas or functional lines between the compressor and plate when I got it, so I added T valves into the design because I wanted to be able to attach gauges and to service it moving forward. While they are designed to not be serviced, there is no reason that they cannot be, other than I guess they would rather sell you a new unit

It took quite a bit of tinkering for me because of the lines (mainly the cap tube length), but if you have the compressor, plate, and all of the tubing between looks in good shape (presumably with the reusable connectors), I suspect that if you installed a T connector on each side, pulled a good vacuum, added gas SLOWLY until you see frost appear on the plate, then keep adding little bits until the frost gets to the top of the plate, you will have a working system.

[ErikFinn]

Hahahaha I can't stop laughing..!!
Let me elaborate before I'll be labeled crazy, hehe.
So I bought the non-working Norcold SCQT-4407 kit I mentioned in my previous post, paid about 140 USD for it.
It's been sitting on my floor for two weeks now as I have been too busy with other stuff.
Today I spent a good 3 or 4 hours googling everything from Schroeder valves to brazing to refrigerant charging to Sawafuji SK-511M 50Hz, and searching the forum and Mr. Kollmans's site for just about anything possible, hoping to get a eureka moment and a lit up light bulb about how to proceed with this unit. Then, soon after getting tired of reading and not understanding half of it I put my specs on, lifted the compressor to my lap, and started to take a closer look at the unit. Everything looked almost brand new, no dinks or knocks or corrosion, all good. Until I took a closer look at the black DC cord.
I'll need to post some questions later but now I must stop laughing before I get hit with instant karma...

[ErikFinn]

Originally Posted by mashenden

Yes, I got mine to work. Mine did not have gas or functional lines between the compressor and plate when I got it, so I added T valves into the design because I wanted to be able to attach gauges and to service it moving forward. While they are designed to not be serviced, there is no reason that they cannot be, other than I guess they would rather sell you a new unit

It took quite a bit of tinkering for me because of the lines (mainly the cap tube length), but if you have the compressor, plate, and all of the tubing between looks in good shape (presumably with the reusable connectors), I suspect that if you installed a T connector on each side, pulled a good vacuum, added gas SLOWLY until you see frost appear on the plate, then keep adding little bits until the frost gets to the top of the plate, you will have a working system.

Hi Mashenden, and thank you for your reply.

During my research I saw some of your threads on other forums and I understand your main issue was finding out the correct length for the capillary tube which had been cut off and an unknown portion was missing?

I appear to have all the parts, but I am still to establish if I can get this to work. I have not yet tried to run it.

Let me ask you another question before I make questions for the whole forum please. You mentioned that you "added T valves". I presume you refer to service valves where one can attach a gauge set or a charging kit or a vacuum pump? Are yours something like this:

Schrader Valves - RPARTS.COM

or:

Refrigerant Base Valve - RPARTS.COM

or some more here:

https://www.grainger.com/category/re...catalog/N-10pd

I do have a gauge set but I have never used it. It is old and the hoses are very stiff, so I wonder if it usable anymore. Therefore I reckon one important factor to remember is to have compatible service valves and a gauge set, and a vacuum pump. Any adaptors would be next to impossible to find here. I would have to establish exactly which valves to get, which gauge set to get, which vacuum pump to get.

Would you have any photos of your installation? I would be especially interested in seeing how and exactly where you installed the T valves.
Also, did you braze them on? Or were they piercing type ones? Did you use 15% silver solder? Did you install a filter drier? I'm trying to establish if I would be able to accomplish this project, thus many dumb questions.

[mashenden]

Wouldn't that be funny if the "biggest" issue was that the ground was not really a ground?

In hindsight, the cap tube issue was my biggest. Luckily it sounds like that is not an issue with your setup.

That is correct, by "tee valve" I meant schrader valve. I added 3 (2 Tees and one straight), which can be seen in the pic below. As it turned out the straight valve was not needed. That line is what the factory used to charge the system, which can now be done using the low side Tee.

A good vacuum pump is needed. The cheap and tempting red type that hook to a separate air compressor to produce a vacuum did not work for me. I ended up buying something like this one: New Single Stage Rotary Vane Vacuum Pump Refrigerant HVAC AC Air R410 R134 R12 | eBay Mine was not exactly like this, and I have never used this particular one, but that is a very close representation of what I used.

Assuming your compressor runs once its properly grounded, personally I would add the valves, draw a good vacuum, charge the unit slowly until you see frost on the evap, stop charging when you see frost start to appear on the top line. See how things cool then. If things get complicated use your old gauge, then buy a new set if needed. Its hard to trust that the frost approach may work, but it really might be all you need if things go in your favor (meaning no compressor issues)






I seem to recall that I also had to flair the Tees so they would slip onto the copper lines - you may be able to find them pre-flaired, though. I bought a flair kit for this as well.

I did not braze, although many would recommend it given the vibrations in a boat. It was a level of expertise that I did not have so I went with what I felt was the next best approach, knowing I could repair things with my tools if a leak ever developed. I used a product called Stay-Brite, which is a silver bearing solder kit.

FYI - Starting tomorrow, I will be away from my PC through 5/20. Sorry.

[ErikFinn]

Dear folks,

so, I would have a few questions to the forum about the Norcold SCQT-4407 please. Unit has these quick connect couplings, please see photos.

Anyone knows how many times these can be connected and disconnected safely without leaking too much gas from system and not introducing any air/moisture into the gas circuit?

I reckon they have been connected once after they left the factory, and also disconnected once after unsuccessful installation by the previous owner ("unit did not produce any cold after running for one day and one night", see possible reason of bad DC connection a few posts up). Of course the previous owner may have done the couplings a few times when trying to troubleshoot, I have no way to find out this.

If I try to test this unit before installing it, it would be good to know how many times I can realistically expect to open and close the couplings. (the unit has no service valves for vacuuming or adding gas). May I do it five times? 10 times? 50 times? 100 times?

Furthermore, how to test the compressor if it is running? May I try to connect DC to the compressor unit without connecting the evaporator plate? Would this be acceptable or not?

Or must I have the evaporator plate connected to the unit? (if yes, must, then I should put the evaporator inside the fridge box, pull all the copper gas lines through the box wall and bulkheads, basically have all the system parts installed into their final positions, instead of testing on the salon table for example, if I want to avoid opening and closing the quick connectors multiple times)

I might be mistaken but my understanding is that there are both "single time" quick connectors and "multiple connect/disconnect" ones on the market, is that correct? Are mine on the photos good for multiple cycles?

Thank you in advance,

Erik

[mashenden]

That is my understanding too - some are one time type connectors, while a newer type are good for multiple times. With the multiple use type, each use loses a bit of gas.

Hooking DC power to the compressor w/o the coil will at least confirm it runs. I would not leave it running for long though.

Once that is confirmed, I think your best bet is to hook everything up on a bench (I used my desk ) and see what happens. You really can't establish a plan until you know what you have (ie is it worth adding Tees, etc). If your system works as-is, then one more connect/disconnect cycle to install it probably will not change the results notably.

I did further testing by putting the coil into a cooler and putting a towel over it - added a digital thermometer to see the results. It worked well enough to cool down beer, which ultimately was my goal.

[mashenden]

Your connectors look to be multi-use. That said, I am not sure I know what the single use type look like. I do know that yours look like mine.

I only had these connectors on the compressor end (one male and one female) because my lines were damaged and partially lost. I ended up cutting mine off to put in the Tees. After removing them, I put them together and air went through them when connected, and not when they were disconnected.

[ErikFinn]

I tried to do some research about the quick connectors and I'm starting to lean towards the opinion that mine are good for multiple connect and disconnect.
Not much info out there but what I found was the following links and mine look pretty similar to the "multiple" ones as opposed to the single shot ones:

https://fisheriessupply.com/adler-ba...r-coldmachines
"Unlike “one-shot” connections, “quick-connect” fittings can be disconnected and reconnected whenever necessary without loss of refrigerant or exposing the system to air or moisture."

http://www2.dometic.com/e51bbe37-70e...22f8a288.fodoc
"Now - The new self-sealing Quick-Connect coupling uses synthetic seals and metal threads, so the couplings can be removed
and reconnected as often as needed with no loss of refrigerant."

Adler / Barbour Quick-Connect Adapters
"Converts pre 2011 ColdMachines to Self Sealing Connections
Allows Compressor and Evaporator to be Disconnected"

[mashenden]

That agrees with what I am seeing on the connectors that I have. Mine are cone shaped as the connector reduces toward the line, which is the newer multiple connection type. It appears from the articles that you found that the one-shot type do not have the cone shape.

I beg you, please hook it all up and give it a go

[ErikFinn]

Originally Posted by mashenden

That agrees with what I am seeing on the connectors that I have. Mine are cone shaped as the connector reduces toward the line, which is the newer multiple connection type. It appears from the articles that you found that the one-shot type do not have the cone shape.

I beg you, please hook it all up and give it a go

I should I suppose..
There is a fan inside the unit, does the exhaust air have a specific ditection or is it just random?
I'm thinking maybe to try to vent this flow somehow effectively