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DN501e Not Cooling (Murphy’s Law Strikes)


bulknoob
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I purchased a used DN501e a few weeks ago and have been cleaning and configuring it in my garage for the last few weeks. Today I made the arrangements to place the machine on Tuesday, and when I got home I noted a metal “ting-ting” sound coming from inside. I opened the machine up and noted that it no longer appeared to be cooling; it was at 65° or so. Its been cooling at a solid 40° for the last few weeks but a night or two ago I turned the thermostat down to see if I could get it a little below 40°. Its also been crazy cold in the midwest, with the last several nights down to zero or a little below, though its of course a little warmer in my garage. The “ting-ting” sound that I heard seriously sounded like a fan blade. Is it possible I turned it too low and something in the refrigeration unit froze up? This is my first machine and I was really looking forward to getting it placed and bringing in a little money before I had to spend anything more on it. Does what I’m experiencing ring any bells for anyone? I’ve unplugged it for now and the weather is supposed to warm up over the next few days. Thanks for any thoughts anyone might have. 

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Is there ice anywhere?

The ting ting could be due to a bent shroud, or an iced up evaporator.

Plug it in, let it run. Whenever something happens, make a note of what is happening and the time that it occurred at. Then post it here.

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You'll need to plug it back in to diagnose it.  You say it was about 65 degrees inside, but what was the ambient temperature (the temperature in the environment it was in)?  That's only important for later.

There are many things that could be going on, but the "ting ting" sound is almost certainly a fan.. but there are two fans in that machine - an evaporator fan and condenser fan.  The condenser fan, located directly in front of the compressor, draws heat from the refrigeration lines and blows that air over the compressor (which also blows heat off of the compressor, effectively cooling it).  The evaporator fan pulls frost and cold air into the rest of the cabinet where the soda is at.

If the "ting ting" was coming from the condenser fan, then you could either have a potential loose fan bearing or something (such as a wire or fan shroud) laying just where the fan can constantly hit it.  In any event, a defective condenser fan causes the compressor to overheat and shut off prematurely before going through a cooling cycle long enough to cool the machine down.

If the "ting ting" is coming from the evaporator, then the likely thing it's hitting is water and/or ice.  I don't usually hear that noise from an evaporator, but if your drain is clogged (located under the evaporator coil) then the backed-up water can slow the fan down enough to allow the evaporator and water below to freeze, causing the evaporator fan to eventually stop spinning and thus causing more ice on the evaporator.

Regardless of the "ting ting" sound, which COULD be a separate issue, if enough ice grows (from a frozen evaporator due to a fan that's not spinning **OR** having low refrigerant in the system), it can touch the thermostat wires and give a false reading, telling the thermostat to shut off as the thermostat thinks it's literally ice-cold.

As orsd said, you have to plug it back in and note where the sound is coming from (evaporator or condenser fan) and note any ice forming anywhere.  The ice should form, with the door shut, in as little as 15 minutes but keep it plugged in for a good hour or two to make sure you figure out where exactly the noise is coming from and if any ice is forming.  A slight frost line across the evaporator coils is normal during a cooling cycle but it goes away very fast.  If it doesn't go away, then describe the ice specifically (location, size, "snow" or solid ice, etc..).

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Thanks for the responses. I plugged the machine in. Ambient air is maybe 35 or 40, inside machine remains 55 - 60. Soft “ting-ting” started again; the sound is very soft, and coming from the mid-section of the machine, not down below where (I believe) the condenser is. The ting-ting is pretty soft while the machine is running, almost like the sound of metal expanding as it warms or cools. But when I pulled the plug on the machine I distinctly heard a fan in the same middle area inside slowing down as the blade came into contact with something. Does that help? Thanks again...

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You need to open it up and look inside.  If the noise is constantly going with the door open and sounds like it's from behind the evaporator coils (behind the delivery chute area) then your evaporator fan is making that noise.  It may have been low on refrigerant.  It's almost impossible to diagnose without doing like i said.

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If there is no ice behind the evaporator then you probably have a worn out bearing in the evaporator motor giving the fan blade too much travel, the motor bracket is loose, the blade is cracked or your air plenum is slightly bent and contacting the blade.  The clearance between the blade and plenum is pretty small.  If the plenum looks in good shape and the blade isn't cracked then you should replace the evaporator fan motor.  Not fun to do.

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13 hours ago, AZVendor said:

If there is no ice behind the evaporator then you probably have a worn out bearing in the evaporator motor giving the fan blade too much travel, the motor bracket is loose, the blade is cracked or your air plenum is slightly bent and contacting the blade.  The clearance between the blade and plenum is pretty small.  If the plenum looks in good shape and the blade isn't cracked then you should replace the evaporator fan motor.  Not fun to do.

Eh, not the worst thing in the world on a 501E.

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Just want to follow up for closure on this.

Had a repair guy come over, and he immediately pointed out that the HVAC power cord inside the door was unplugged. Feeling way dumb. I had uplugged it while working on the machine and forgotten about it. He did fix a prominent rattle in the machine so it wasn’t a total waste.

Sorry to waste people’s time with this dumb question, thanks again for all of the ideas. 

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LOL, don't feel too bad.

There was an old 368 sitting in the corner of my shop for a couple years, never could figure out the problem, I tried everything, turns out one of the motor switch tabs never made it into the connector of the harness. &%#$&#$*

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5 hours ago, bulknoob said:

Just want to follow up for closure on this.

Had a repair guy come over, and he immediately pointed out that the HVAC power cord inside the door was unplugged. Feeling way dumb. I had uplugged it while working on the machine and forgotten about it. He did fix a prominent rattle in the machine so it wasn’t a total waste.

Sorry to waste people’s time with this dumb question, thanks again for all of the ideas. 

that happened to me about a month ago.  It's scary when your machine's not cooling and you are trying to troubleshoot but a big whew when you know its something simple as that.

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