Tagged: Donper BH740
MemberJune 9, 2020 at 5:56 pm
Hi, own a Donper BH7480 frozen yogurt machine. Recently I noticed water leaking from the bottom of the machine after an hour of operation. I opened it up and saw that parts of the compressor were frozen! I immediately turned off and unplugged the machine. Any idea why this is happening all of a sudden?
I have provided pictures the compressor immediately after I found out it was freezing up.
MemberJune 9, 2020 at 11:33 pm
Unless you are EPA 608 certified, familiar with how the refigeration cycle works and have a manifold gauge there will be very little you can do. Check the unit to ensure proper air flow and inspect the unit for signs of a refigerant leak.
Issues could range from something restricting the flow of refigerant through the system to low charge of refigerant.
You could call a local commercial kitchen equipment repair company but I would try a reputable HVAC/R company in your area. I have found them to more cost efficient most of the time.
MemberJune 10, 2020 at 8:41 am
It’s normal for a freezer to have frost on the suction side of the compressor. The question is how much the machine is used and how fast it freeze’s product. If the unit is pumping out a lot of mix, or being forced to make more than it was designed for , you may need another machine. Does the compressor run excessive in between demand? There is a sight grass neer the filter dryer that will clue you in if you have a low charge. If you have bubbles in the sight glass after the compressor runs for about a minute you either have a condenser problem or low charge. The condenser problem can easily be determined by seeing how hot the liquid line is at the filter dryer. Should be about 10 to 20 degrees warmer than ambient air temp.
The other thing with soft serve machines is the control system. But long running would cause freeze up of the product. When you draw product it should measure about 19 F if you are using a 8 to 14 percent fat product. Dole whip is a whole another problem, so I won’t go there.
MemberJune 10, 2020 at 10:31 am
Refrigerant is generally speaking, around 10-20*F colder than the desired temperatue of the the product.
In fridges, it’s 10*F normally, so if you want a 37*F box, the refrigerant needs to be 27*F, just rules of thumb.
So if your freezer/ice thing is lets say 0*F then your refrigerant would be -10 or -20*F which is very, very cold and well below freezing.
There’s a common misconception in the refrigeration world that a frozen compressor is bad, it’s flooding, it’s dying.
All it means when there’s frost or ice on lines or the compressor body is that it’s below 32*F and there’s humidity, that’s all it tells you.
Then you go into, well what is it? if it’s a fridge, it’s not good, that’s for sure almost every time. But a freezer, blast chiller, whatever, it’s normal.
The question in your case would be, why is it freezing up now if it didn’t before? Is it insulated?
MemberJune 10, 2020 at 2:06 pm
I don’t know where you are at or the climate your in, but with the reopening of enterprise I suspect you are in a humid hot area and everyone is looking for a cone. That means a lot of load on the machine. Especially being a single compressor and two evaporator cylinders. So your icing would be considered normal. When you put the machine in standby or night of coarse it would melt back into water and drain to the floor or drip pan. (If it has one) It’s not a machine brand I have seen in my area, but is a lot less expensive than a Taylor, Electrofreeze or Carpagino that are the workhorses here.
MemberJune 10, 2020 at 2:57 pm
Our business is in Anchorage, Alaska.
I have 4 other Donper BH7480, and I’ve never had issues with any of those machines.
It only happens when it is on Standby mode. If I just run the machine normally, it will not freeze up and the machine will dispense normally (although the temperature of the product is cooler than normal). When on standby mode however, you can hear the machine and the fans constantly working. It will stop after awhile, but that’s when the frost begins building on the condenser. I removed the front cover to try to reveal the two cylinders to see if the product was still in “yogurt” form, only to find out that it’s frozen shut. So I’m assuming that when in standby mode, my machine is overfreezing the product when it is supposed to keep it cool.
I forgot to note that I had an issue with a faulty temperature sensor on the problem machine. I replaced it with a used one from another machine, and this is when the frozen condenser and frozen product on standby mode started happening. I ordered a brand new one today and hopefully this solves the issue.
Thank you for the advice!
MemberJune 11, 2020 at 9:02 am
Now your zeroing in on what you have for us. It most likely is a temp sensor, rotational sensor, or limit switch0 . Do you have and alarm codes in the display like “–” , “Cb”, “AL” , or “LL”
A code will help narrow this down. Everything is controlled by the main board from sensors, so any wiring connections should also be checked. You can find a service manual here: https://www.heritageparts.com/medias/8864851361822.pdf?context=bWFzdGVyfHJvb3R8MTM2MzIyNXxhcHBsaWNhdGlvbi9wZGZ8aDYzL2g1Ny84ODY0ODUxMzYxODIyLnBkZnxjMTAwYTk1YWUxZTMwYzA5MGJlMmFmOTllYTE4NDY2NjNmZGZlZDJjMzgyNGM0NjI1ODdmMTgyOWU1MDk2ZWFi
I don’t know if you have a understanding of soft serve machine control. Basically they run till the correct firmness is achieved. (the rotational sensor) Then wait till the handle is pulled to start the auger and compressor again. (limit switches above handles) But they also use thermistors to monitor the cylinder temp and tank temp
MemberJune 11, 2020 at 9:14 am
I forgot to ask if you notice this on both sides or just one. What value shows in the displays when you first hit auto and the mix is still liquid?
MemberJune 18, 2020 at 4:13 pm
So my new temperature sensors came in from Donper and I replaced them, but I am still having the same issues. After replacing the temp sensor, I turn on “auto” on both sides to let the machine operate as normal. I put it into standby mode over night to see if the issue was resolved. Came back in the morning to see the compressor had built up ice like the pictures in the first post and the product inside the cylinders were frozen. I know the product inside is frozen because setting the machine to “Wash” will cause the two beater motors to stall and eventually give me a “–” error on both sides. Also, I cannot remove the dispenser door. I have to wait several hours for the product to thaw to dispense any product.
Again, the compressor only builds ice when the machine is in “bb” mode or Standby mode, in addition to the yogurt mix in the cylinders freezing up.
To answer some of your specific questions fixbear, when I first hit auto on both sides after the machine sits idle to room temperature and adding fresh mix, the display reads “87” on both sides, then continues to operate as normal.
A previous machine had the error “AL” on one side, in which I also replaced the temp sensor and it solved the issue. The machine I am having issues with now also displayed the error “AL,” so I figured it was another temperature sensor issue. Replacing the temperature sensor with the new one I received today resolved the “AL” issue, but now the liquid yogurt mix is completely freezing in the cylinders and the compressor is building ice ONLY in standby mode. Normal operation on the “auto” mode works as normal.
MemberJune 11, 2020 at 9:22 am
Temp sensors can easily be tested with a ohm meter and accurate thermometer. But finding a chart of the correct value for a particular one can be challenging. I always like to check the values of a new one and record them in the manual or hidden inside of a machine for future reference.
MemberJune 18, 2020 at 6:05 pm
ok, “AL” is cylinder alarm for low temp. Obvious due to freeze up. Now to find why. Normally it’s a temp sensor open or not bonded to the cylinder to conduct the heat correctly. But if the mix motor continues to run it means it may be the rotation sensor or limit switch on the handles. The Micro switch above the handles calls for auger and cooling and overrides the temp control to be able to pull a serving. The proximity switch on the gear box is the rotation-load sensor that stops the refrigeration.
Now there is another possibility, that the compressor contactor is stuck in the on position or hangs. You’ll need to use a Digital voltmeter to determine if it is getting coil power when it shouldn’t or if the control is telling it to freeze. Make sure your thermistors are wired correctly for polarity and on the right terminals. The 87 is the start temp of the thermistor. A relative number that will drop as it freezes.
By the way, have you checked the belts and motor tension. If they are slipping it will not trip the rotation sensor. Check for glazing and tension.
MemberJune 18, 2020 at 6:27 pm
Sorry, I was looking through my notes again and made a mistake on the error code I was receiving. The code I had was “AH,” not “AL.” According to the manual, AH means either the temp in the cylinders was over 140f or there was an error with the temperature sensor. Obviously it wasn’t a cylinder issue because the product was frozen in the cylinder, so I replaced the temp sensor to solve the AH issue. However, as Ive stated before, while on Standby my compressor freezes over and the product becomes frozen in the cylinders.
The motor belts are new and we have doubled checked the tension.
Again, this only happens on standby mode. I dont think the motors turn while on standby, so I dont think that the motors are an issue
MemberJune 18, 2020 at 6:53 pm
I forgot to ask you where you hardness setting are and what your using for a mix? Both the 5 MIN and 15 MIN.
MemberJune 18, 2020 at 6:58 pm
5 second setting is at 8
15 second setting is -3
Both sides are the same
MemberJune 19, 2020 at 10:04 am
Are you still getting a high alarm?
MemberJune 19, 2020 at 10:20 am
You will want to check the thermistors again at the board with a ohmmeter. To do this you will need very narrow and sharp probes. Unplug one and test from the back of the plug, not the front so that you don’t damage the connection. Also when the machine is in standby feel the cap tubes to see if the solenoids are leaking. You can unplug the coil and feel a temp change. Then monitor the voltage to the coil to see if there is a call for cooling.
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