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Refrigeration Troubleshooting


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As suggested in another thread, here is a thread for discussion of refrigeration problems and how to troubleshoot them. So if you guys will add some good content and pics to make it helpful and informative I will be happy to pin it so that it stays at the top of the forum.

 

Let's try to keep this one on topic. ;D

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What causes a machine to freeze up?

What can be done to prevent it?

 

I have a Dixie Narco 501e (luckily owned by Pepsi) that for the past 3 years every spring/summer starts freezing up.  Pepsi has been out several times & has replaced the refrigeration deck at least twice.  They have also changed the thermostat at least once.  The door gasket makes a good seal however after the last time Pepsi was there I noticed that the door seal had some type of stuff all around it (possibly petroleum jelly but I am not sure). 

 

I went to fill it last Friday & noticed that it was freezing up again.

gallery_6992_242_355701.jpg

When I left on Friday I had the location unplug the machine to thaw it out over the weekend & they said that they would plug it back in on Monday morning.  I am going back to the location again on Friday to see if it is still freezing up.

gallery_6992_149_12052.jpg

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I suppose it could be a problematic evaporator fan that isn't working well enough but I am no refrigeration expert.  I only throw it out there because (to my knowledge) the evaporator fan is the only thing left in the refrigeration system that has not been changed... and if the evaporator fan doesn't work or is too weak, it should allow frost to form.

 

Your frost appears to be growing everywhere so that tells me that your refrigeration deck is probably good but the thermostat could be bad but I still wonder about the evaporator fan.

 

Also, you may be happy that it's Pepsi's machine but how "fast" do they come out to fix them when they break?

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There are a few things that you can do to help your refrigeration system work it's best. 

 

1 ) Always, always keep the coils clean. Do not allow blankets of dust to grow on the condenser coil. ( This is especially bad in carpeted areas and in clothing stores. ) You can buy a foaming cleaner product ( it looks remarkably like Scrubbin' Bubbles ) and use that if it's ridiculously dirty. If the fins are all bent to crap, try and straighten them out a bit. Try and ensure the shrouding remains where it belongs. ( I know how tempting it can be to just bend the shrouding down and out of the way. Don't do it. Short cuts lead to more work later. )

 

2 ) Always, always keep the evaporator coils clean. Do not store extra product under the delivery bin. ( I once pulled out a dozen sodas that were out of date by ten years, from one machine. ) If you look under there with a flashlight, and see a bunch of paper towels or Aquafina lables latched onto the evaporator, held fast by the fan, remove them and try and make sure it doesn't happen again.

 

3 ) Keep the cabinet sealed, as much as possible. Do not allow the gasket around the inner door on a stacker machine to peel away. Glue that sucker down if it starts to come off. 

3a ) If somehow you've ended up with a soda machine that's missing the inner door. Replace it. ( I once had a machine that kept having refrigeration problems. It had been installed without an inner door. Friends don't let the set crew install machines while drunk. )

3b ) Ensure there is enough room for the machine to breath. Be sure you have AT LEAST four inches of space behind the machine, for hot air to exhaust to.

 

4 ) Water is a byproduct of the refrigeration cycle. The drip tray is your friend. If it is constantly filling up and overflowing, your deck is running too much. Move to a cooler climate, or see steps 1, 2, and 3. Can't move to Alaska? Ok, then can you move the machine out of direct sun? ( Do it, if you can. ) Can you put some kind of sun shield around it? ( Do it, if you can ) If the machine is modern enough to have timed controls and the location is one that closes down for the night, consider programming a "holding temperature" of 55-ish degrees overnight.

4a ) If you have a block of ice on the evaporator, know that when it thaws, it's going to create more water than your drip tray will hold. Either *( carefully )* chip away some of the larger blocks of ice and thaw them by hand, or pile a bunch of towels around the drip tray for overflows. If your customer has really nice floors, you should consider taking the couple of hours to thaw that block of ice by hand. Be *very* careful if you chisel the ice away. Refrigeration lines break far more easily than you might expect.

4b ) Double check and make sure that the hose goes into the drip tray. Sometimes machines get manhandled around a bit, and the hose comes out of the drip tray. Having to pay for an account to replace their linoleum in the break room can be expensive. Be especially watchful on DN5591s. Older ones have a plastic drip tray that looks *exactly* like tupperware. The hot lines go through it, ( deliberately, to help evaporate condensate ) but as the unit starts to fail, it can melt right through the bottom.

 


Sometimes you'll find a problem with the control board is keeping the compressor running constantly. ( Newer machines, mostly. ) In these cases, turning the machine off and on again may bring them around for a while. ( But keep an eye on the machine going into the future. )

 

Older machines, check the theromostat. Turn it all the way up, all the way down. Does the compressor click off and on at certain points in the travel of the dial? If not, replace it. Thermostats are an older technology, and many of them can be swapped for each other, even if they look slightly different. ( But, as always, test test test. )

 

It's been said that 50% of the refrigeration problems that you'll have are electrical. Not sure I believe that 100%, but keep it in mind. 

 

ALWAYS, ALWAYS keep your eyes out for loose ground wires. They cause the weirdest problems.

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Also, you may be happy that it's Pepsi's machine but how "fast" do they come out to fix them when they break?

In my area I call the repair in & a Pepsi repair tech comes within 24 (business) hours or less every time. If its early enough in the day then they are usually there the same day.  Coke or rather Great Plains Coca-Cola are the ones that are less than stellar in this area to put it nicely.

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I am quite certain that I am forgetting some words of wisdom. I'll be dropping back by this thread in the future. I'm positive that there are other voices on the forums here with some great knowledge about refrigeration matters. Refrigeration is not my strong suit. I've never been certified, and in fact I haven't had gauges hooked up to a machine in fifteen years. 99% of the soda machines I've had my hands in since then have belonged to Coke or Pepsi, and with the sealed decks used in most vending machines, it's not worth the effort to solder in ports and do the refer work yourself. 

 

Cold food machines ( also know as the Wheel of Death (tm ) ) do have serviceable refer units. But I've luckily always worked at a company that has someone who's strong suite *is* the gauges and the refrigeration.

 

Cold cup machines had also had serviceable refer units, but I still have nightmares about the hideous doom that can be found inside a machine with open pits of syrup inside them. So I really don't want to talk about them.

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In my area I call the repair in & a Pepsi repair tech comes within 24 (business) hours or less every time. If its early enough in the day then they are usually there the same day.  Coke or rather Great Plains Coca-Cola are the ones that are less than stellar in this area to put it nicely.

 

That's pretty good from what I hear.

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That cold control is problematic. They had recalls on that type and was discontinued at one point... Also for some reason Dixie decided to put it in that dead air space behind the evaporator. Bad spot. It is a airover temp control that never gets air over. That is why I say dead air space......

 

#1Make sure vendor is level. Make sure it isn't against the wall. If the vendor is against the wall it will generate unnecessary heat and will migrate into the lower cabinet causing the compressor to cycle to often. When this happens the evaporator has not enough time to dry out between cycles.Tech are always taking short cuts and when replace cooling decks they will also throw away the metal cover that covers the compressor. That cover has a reason. #1 it supports the cabinet so it dose't twist and helps keep it level. #2 it keeps the air flow going out the back. Do not leave it off. 

 

#2 Replace the temp control.... Take the cap tube and route it around the Accumulator (That big round thing coming out of the evaporator) bend the cap tube so it rest about the middle of the evaporator but not touching it.  Turn the cold control to 4-5.

 

#3 If door is sagging it is most likely because the christmas trees are missing from the sign face or are broken of. The door should close without having to push hard. T-Handle should turn smoothly. Every 501-E I have service the door won't align with the stud and nut. Most seattle after being placed and then after filling they get hard to close. Look at the nut housing. They are in the most upper height they can be. Loosen the 7/16 nuts and let it drop down to the lowest. Then loosen the two phillips screw on the cage nut just enough the cage will move left to right freely. Lubricate the stud with white lithium grease. After you are done you should be able to turn t-handle with just you thumb to open and close.

 

#4 Check drain hose and make sure it is in place. It can allow heat to migrate into cabinet if missing. Heat is attracted to cold. 

 

When servicing look at door seal for condensation. If there is condensation anywhere around the seal that is where the hot air is getting in.

 

And last make sure the T-handle is tight. Turn till tight and back off enough to lock. 

 

Some Pepsi vendors had a 1/4 turn lock... Go back to a screw in handle

 

If you are using a TriTech lock it may need adjusting. There is a bolt on the back of the lock that can be used for making door looser or tighter.

 

Vendo has the spring loaded cage nut. Make sure you are tightening it after closing. Don't just slam it and walk away. 

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What causes a machine to freeze up?

What can be done to prevent it?

 

I have a Dixie Narco 501e (luckily owned by Pepsi) that for the past 3 years every spring/summer starts freezing up.  Pepsi has been out several times & has replaced the refrigeration deck at least twice.  They have also changed the thermostat at least once.  The door gasket makes a good seal however after the last time Pepsi was there I noticed that the door seal had some type of stuff all around it (possibly petroleum jelly but I am not sure). 

 

I went to fill it last Friday & noticed that it was freezing up again.

gallery_6992_242_355701.jpg

When I left on Friday I had the location unplug the machine to thaw it out over the weekend & they said that they would plug it back in on Monday morning.  I am going back to the location again on Friday to see if it is still freezing up.

gallery_6992_149_12052.jpg

 

 

Good pics Randy

 

The best way to thaw out is to turn cold control off. Make sure you have a larger bucket underneath to catch the water. Close the door and come back in 3-4 hours. The fan motors (two 9 watt fan motors put off a lot of heat) will thaw it out quickly. Just unplugging the vendor will take days.

 

There is two kinds of ice

#1 is frost... White flaky ice frost is generated by a well charge system.

 

#2 Ice ....  This is clear and is generated by a low charged system.  Ice forms because the evaporator is to warm. Under normal operation the evaporators temps are very low 10 degrees to -10 degrees. A low charge is usually indicated by clear ice at the top of the evaporator.

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This is a good start so far, how about someone posting some pics of complete system and labeling the components with a brief explanation of what role they play in the whole system. I think a lot of newer guys would love to better know the terminology so they could ask better questions.

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Even some short videos on how to remove a refer decks on different make/model machines I think would be useful if someone is prepared to make them..

 

Would this be an option mission or would it take up to much space on the site?

 

Maybe it would be easier if Alden added them to his "How To Videos" section on his site.. just don't expect there to be any videos on how to remove a refer deck on a USI unless he was using dynamite!!  ;D

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Even some short videos on how to remove a refer decks on different make/model machines I think would be useful if someone is prepared to make them..

 

Would this be an option mission or would it take up to much space on the site?

 

Maybe it would be easier if Alden added them to his "How To Videos" section on his site.. just don't expect there to be any videos on how to remove a refer deck on a USI unless he was using dynamite!!  ;D

I doubt Alden has much enthusiasm for working on USI reefer decks anymore.  After his last adventure I'm afraid his video would more resemble the "Texas Chainsaw Massacres" than anything instructional.  ;D  ;D  ;D

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I'm sorry I failed to take pictures of the blanket of fuzz on the compressor I worked on today. It was truly epic, of "hipster beard" proportions. I cleaned it off without even thinking about it. Then said to myself, "Wait, self, it might be instructional to show pictures of this on the internet." 

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I'm sorry I failed to take pictures of the blanket of fuzz on the compressor I worked on today. It was truly epic, of "hipster beard" proportions. I cleaned it off without even thinking about it. Then said to myself, "Wait, self, it might be instructional to show pictures of this on the internet." 

Is this basically what you did?

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So I got a call today for a dn 368 that wasn't very cold. There's frost all around the evaporator coil and nearby pieces. I turned the t stat off, compressor kicked off, then I started looking around. I guess the t stat is okay but the frost won't allow the machine to cool. There is solid ice at the bottom of the tank and i'm going to take the tray off to see how it looks on top.

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Nothing appeared to be aligned "wrong" yet the door ans the plastic delivery port do not line up. There is about a half inch gap on one side and zero gap on the other.

When I checked the hinges, nothing was obvious.

I concluded a few potential culprits.

My hinges were installed wrong.

The holes in the inner door were drilled in the wrong place.

The delivery door cutout is in the wrong place.

The delivery "port" is bent.

I believed it is [what I'm calling] the plastic port. When I push the door, there is a clear misalignment of the angle of the swing and the port. It catches on the bottom right but it's not close on the bottom left.

So... I suppose the door hinges could be worse than they look, but something is definitely not aligned. Maybe the delivery door is slightly crooked.

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