Sunday, September 20, 2015

How To Fix Fridge Freezing Problem On Dometic Refrigerator

The Swedish made Dometic refrigerator is made for RV use, where it can be run from electricity or propane. Overall, it's well designed, but for whatever reason it provides no temperature adjustment. It relies on its thermistor being perfect, within a very tight tolerance.

But we all know how that works out, right? The world is never ideal, and two random thermistors off the production line might run their fridges at different temperatures. And certainly the characteristics change slightly over time. That's why almost every refrigerator on earth adds a simple variable resister to provide control.

The Problem


My Dometic 2652 Two Way fridge works, but the fridge gets too cold. Like, in the 20s. I found the service manual to this fridge, and it has a troubleshooting portion that specifically mentions this issue as either a problem with the resistor or the control board. Searching the Google machine yields others saying the same thing.



Testing


If your fridge is having the same problem, there's almost no reason to do the test, because the aftermarket kit on eBay offers the adjustment you want either way. But if money is an issue, you can test the existing thermistor.

I cut mine off to test it, figuring I could just splice it back on if it worked. But you don't have to cut it off.

The original thermistor, snipped off


The official test involves putting it in a glass of icewater and measuring the resistance. So what you can do is unclip it, and put in a glass of ice water inside the fridge. And then disconnect the 120V and the 12V systems, pull the connector, and measure the resistance straight from the connector.

In a glass of icewater, the thermistor should read 10k ohms on a multimeter. When the control board reads 10k ohms, it figures the fridge is the right temperature and turns the motor off. So if yours reads lower, then you have solved your problem.

If your thermistor has the correct reading, then it has to be the control board. I read somewhere that the relay goes bad on the control board.

My thermistor measured 5 ohms in a glass of icewater! Which means it would never tell the fridge to stop cooling, and the fridge is happy to comply. Just as an aside, I think you cold probably intentionally turn the fridge into a freezer if you so desired.

Above, you can see that I circled the connector where the thermistor connects to the controller board

Aftermarket Thermistor Kit

There is an aftermarket kit from a web site and seller on eBay that's not too hard to find with a search. I've even seen youtube videos of these aftermarket kits being used. I noticed it was a dollar cheaper direct from their web site and they take PayPal which allows you to file a claim if you don't get your order.

I assume the kit is just a thermistor and variable resister in a series, but I'm no electronics genius, and I also need a fridge very badly.

So, I ordered the kit. I thought "aww jeez, it's going to take forever, isn't it?" but I received it about a week after I ordered it, so it must ship from inside the USA.




Replacing The Thermistor

Their web site provides good instructions. I'll be honest here. I left the power connected when I snipped the original thermistor off, and left it connected when I put the new one on. My thought was that there isn't much DC current going through that thermistor, and I guessed that a brief 0 ohms reading wouldn't fry the control board. But everyone else says disconnect both 120V and 12V systems first, so you should do that.

You'll want to strip the wires to maybe 3/8 inch. Make sure to twist the ends tight, so they go right into the barrel nuts. The new thermistor has a sticky backing, and it's really sticky. You're supposed to make the area clean and dry before you stick it, but my fridge had been off for a few weeks, so it was already dry.

I mounted it upside down because I didn't have my glasses on. I realized my mistake an instant later, but the backing is so sticky, I almost hurt my hand when it finally broke free. I mounted it correctly a little farther away from the fins, figuring I'd rather have it closer to where I can see it, and the adjustment can always compensate from it not being in the recommended place. Also, I notice in the videos and photos of others doing it, that nobody else is mounting it that close to the fins, either.







Testing The Fix


I always say, if you didn't test it, then it doesn't work. I bought a little thermometer that hangs in the fridge and has a little red band showing when the fridge is in the ideal temperature range. Unlike a freezer, a fridge has a very narrow band where it's useful. Too warm, and everything you cook will make your family sick, and too cold, like mine was, and your salad is frozen. Not good.

The adjustment seems to be working so far. The aftermarket kits fixes a glaring design flaw in this Dometic refrigerator. Someday I may solder the connections and put heat shrink tubing. The barrel nuts look a little "ghetto" but don't affect the functionality of the unit.



Final Thoughts


These fridges have a reputation for being quirky, so having an adjustable temperature takes away one of its quirks. But if you wanted to keep the fridge factory original, then you could always get the original thermistor from Amazon, ebay--lots of places.

Notes:



  • RV refrigerators that can operate off of propane are much different from the ones you are used to seeing in your kitchen. They take longer to get cold, so changing the temperature dial could take several hours to reflect the new setting.



Thursday, September 3, 2015

How To Fix Nozzle Problems On Rug Doctor Portable Spot Remover

It only took a quick Google search to realize that average users weren't taking apart this machine. But the nozzle was clogged, and I have 4 dogs. My machine was also about 2 months old--too late to return it to Amazon. I could see a couple reviews where people said that Rug Doctor wasn't very responsive.

Did I mention that I have 4 dogs? I really needed to clean up a few spots, and failure was not an option.



The Problem


The nozzle on my Rug Doctor Portable Spot Cleaner was clogged. Pressing the trigger with the unit on gave me two tiny streams shooting out left and right, about half a foot from where the brush head is expecting to pick up that water.

My brother suggested running just a tank of plain hot water through it. This didn't do much. It was obvious there was something clogging the nozzle. I'm handy with a screwdriver, no problem, right? Wrong. This project only took 3 hours total, but I can strip down a Hoover Steam Vac and rebuild it top-to-bottom in about an hour, just because it's easy to work on.

This unit ... is not easy to work on. I would place this end towards the upper end of difficulty of all the appliances I've fixed. Years ago I had a Mercedes, and it was so complex that it always gave me the feeling that I wasn't qualified to operate it--this Rug Doctor gives me the same feeling. This is a precise machine.

If you are handy with a screwdriver and have OCD about putting things back together, it is entirely possible for the average person to take about the brush unit to service the few servicable parts in there, like the clean fluid switch and the spray nozzle.


The Solution


Since the nozzle doesn't easily come out, I had to disassemble the brush unit to get to it so I could poke out whatever was clogging it from the other side with a needle. I originally thought about poking the needle through without taking it apart, but it seemed like if there was debris clogging the nozzle, pushing it in wouldn't stop it from needing to come out. No, I needed to be on the other size of it.

Note that the nozzle probably should've been replaced, since clearing it with a needle bored it out, and now the nozzle sprays a little wider than the head.

Disassembly Notes


Since this was my first time taking this apart and I had no manual, I have no idea if there is an easier way to do this. From looking at this unit disassembled for a few days and studying it, I'm pretty sure that the entire unit needs to come apart to take out the nozzle or do basically anything to the internals. But I could be wrong, and I'm about as far away from being an authorized repair of these machines as someone can be.

Also, there seem to my old eyes to be two lengths of screws, with one being slightly smaller. So pay attention and make sure you put the smaller ones back where they belong.

The terminology I'm using could be all wrong, too. I've never taken a unit quite like this apart before, so I could be naming everything incorrectly. As the kids would say, I'm a Rug Doctor Noob.

Head Construction


The brush head unit has the sprayer, brushes and brush agitator motor, spray nozzle, and finally, it also picks up the dirty water. This makes it real easy on the user, who just has to pull the trigger and drag the head along.

There's basically 4 pieces holding this thing together: the brushes and three red plastic shells. The unit has kind of a main back plate where the two sides attach, forming a plastic cage that holds the agitator motor in place.



Preparing For The Job


You'll probably want a small zip-lock sandwich baggy to hold the small parts while you are working on the unit. You will also want a good quality Phillips screwdriver so you don't strip the screws, because they are cheap screws.

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Step 1 - Diassembly Of Brush Head


1. Take off brushes

First you want to take off what I am calling the brush block. There are two screws on the brush block itself that hold it in, including the agitator brush. If I remember, the top screw was a little smaller, so pay attention.



At this point the brush block should slide right out as two pieces.

2. Take out all the screws

What I did was took out every single screw at that point. It might be possible to take off just the side with the nozzle on it. Under the spray trigger, it says "SOAP" and you might try taking off all the screws on the side that says "SO" on it.

But again, I just took all the screws out and let everything just kind of fall into its component pieces on the counter.



3. Catch the spring

There is a spring which gives the spray trigger a nice, tactile feel to it. You'll want to catch that spring and put it in your parts baggy.

4. Catch the trigger

The spray trigger will probably fall off when the head is opened, so make sure to capture it an put it in the parts baggy.

5. Separate the two halves

At this point you should have both halves of the unit's shell separated, with the agitator unit laying on the back plate--the third piece of the shell.







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Step 2 - Take The Spray Nozzle Off


The spray nozzle should be dangling there once you have the two sides apart. It's held on by a little zip tie. I didn't want to risk cutting the spray hose, so I just slid the zip tie off, and it worked!

At this point you should be holding the grey spray nozzle in your hand.



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Step 3 - Fix Or Replace Nozzle


Where, oh where did I go wrong? I only used clean, hot, tap water with store bought cleaning solution. I wasn't abusive to the unit at all. At this point I'm almost convinced that it had some debris in it from the factory.

I fixed my spray nozzle by putting a needle through it from a cheap sewing kit I had. Putting the needle through it, I could feel gritty stuff in it, and afterwards, when I tested it, my little Rug Doctor now lays down almost double the water it did on the day I first used it.

The only way to know for sure that whatever you did to the nozzle will work, is by putting it back together and seeing for yourself. Since this thing is a hassle to put back together, it might be feasible to just replace the nozzle.


Step 4 - Reassemble Unit

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1. Re-attach the sprayer nozzle

I didn't replace the zip tie on mine, but if you do, know that the nozzle is keyed to the "SO" half of the unit. You won't be able to twist the sprayer hose, so make sure the nozzle is oriented right before you make it too tight to turn.

2. Attach the "SO" half of shell

At least this is how I started to reassemble everything. I first put the screw in the bottom just to help, hold it together. And then I put in the two screws for the "SO" half of the brush agitator unit. The agitator is very picky how it goes on, and it took me a while to decide on this as the first step of putting the shell back together.

3. Put the screws back in "SO" half of shell

Take note to put the screws back in the right places.

3. Attach the "AP" half of the shell

This is the hard part. First I put in the grey sprayer trigger. That's the easy part. Next, the sprayer switch has two little holes that have to slide onto the shell. But there's not much slack in the wires, so once you attach the switch, you have to do the rest while trying to keep everything from falling apart.

If everything goes well, put the spring onto the sprayer trigger, letting it lay on its side so it doesn't fall out while you fumble with the rest.

Now, if all that isn't enough, the shell is very picky about how it snaps together. The agitator makes it even worse because it is also picky.

If all goes well, the other half of the shell snaps into place with no gaps anywhere. If you have gaps in the brush unit, then you did something wrong.

4. Test the spray trigger feel

Before you put the screws back in and pat yourself on the back, test the trigger to make sure it has the right feel to it. If you messed up with the trigger spring, you will know it.

5. Put the screws back in

Put the screws back in the "AP" half of the shell. There's a couple small ones, but the lengths are so close, I'm not convinced it really matters which screws go where, but don't quote me on that. I did look at the attachment points for every screw, and as far as I could tell, the shorter ones were just a couple places they could save .00001 cents using less steel.

4. Attach the brush block

This is the easy part. Put the thin part that agitates into the holes in the agitator unit. You can move the white plastic agitator to line the holes up if you need to. The brush should just fit right in.

Now just put the rest of the brush block back on. It should just slide right into place without any fuss.

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Step 5 - Test your work


As a computer engineer I've always said that if you haven't tested it, then it doesn't work. Which is why I would fill the tank with clean water--don't waste cleaning solution until you know it works--and power it on, specifically looking at the spray pattern and making sure the agitator brush moves like it should

Final Notes


  • As noted earlier, this is a fairly complicated task given the precise nature of the main brush/spray/pickup unit.
  • I'm sure taking the unit apart voids the warranty, so before you mess with your unit, I would make an attempt to return it to wherever you purchased it.