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True 49 cu. ft. / 1388 liter Commercial Freezer GDIM-49NT Questions & Answers
We have a true T49F freezer and the evaporator
Freezers have a sensor that is referred to as a "Fan Delay/Defrost Terminator". It senses the temp during the defrost cycle. Usually, when the evap temp reaches about 50 degrees, there should not be any frost or ice on it. This device terminates the defrost cycle. It also keeps the fans off so warm air is not circulated. When the evap gets to about 20 degress or so, the sensor switches on the evap fans. If the fans are not coming on, either the sensor is bad or the evap is not reaching the proper temp to cause the sensor to turn on the fans.
Hope is helps to clear up some things and point you in a direction as to what might be going on.
I have a True Freezer Model T-49. It works fine but every 3 or 4
This sounds like a stuck relay to me. I have seen this problem before. The defrost clock kills power to the compressor relay coil during defrost. If the contacts in the relay are welded together the compressor runs while unit is trying to defrost. On newer units this relay is mounted in base of unit on the side or back of the electrical box near center bottom of unit. The compressor relay is a small rectangular box with 4 wires attached. It can be replaced with a single pole 20 amp contactor with a 120 volt coil/ or 240 volt. Check the units name plate voltage rating and ratings on old relay! ;)
Coils ice up
My best guess is that the drain has some debris in it and the defrosted water from the coil is being picked up and being re-frozen against the coil and freezing up the drain pan. The defrost timer may have failed, the defrost termination button fastened to the coil may have failed, the defrost heater on the coil itself may have separated from the coil or just outright failed. Hope this helps and good luck.
Normal Operating pressure for true 2 door Freezer
The pressures depend, somewhat, on the expansion device,i.e. a TXV or Cap Tube. Take a pressure reading, then convert it to a temperature. The evap temp should be right at 10 colder than the box temp. Remember, heat flows to cold so the evap has to "Lead the Load" in order to cool. In many cases, the condensing pressure is usually ambient temp, plus 30, then convert to a pressure. These are general accepted practices that have been used for many years.
Hope this helps
This evaporator coil gets all iced up about once a month and quits cooling
Check the condenser coil is clear and clean, and thermostat set about 2 or 3. Also check the fan is running with door closed, and no food is too close to the top stopping the airflow over the evaporator. It may be as simple as a blocked drain backing up - check the drain tube next time it defrosts.
Evaporator unit keeps on building ice. question
I'll try to give you the "Readers Digest" version.
First, make sure there is no ice build up on the evap. Light frost is O.K. as long as it does not effect air flow. (Very Important). All fans need to be running. Again, an air flow thing. There should be some product in the box but not too close to the evap. Again, an air flow thing.
The expansion device can effect your pressures to some degree i.e. Cap tube vs. TXV.
As a general rule of thumb, which I use almost everyday when it comes to pressures:
Low side is based on the temp difference between evap temp and condition space in the box. In freezers, it is almost always 10 degrees. If the box is 0 degrees then the evap needs to be at a minus 10 degrees. That is a pressure for R-404A of 24.5 psi. This only holds true when the temp in the box is approching set temp. I would say, about +10 degrees. 0 Degrees for the evap for R-404A is 33.5 psi.
High side should be ambient temp +30 degrees and then convert to a pressure for the refrigerant.
Example: 75 degrees in the room, +30 degrees equals 105 degrees. Now 105 degrees converted to a R-404A pressure is 253 psi. This will get you very close to the desired high side pressure.
I would look at low side first to see if it is within reason. Don't let the high side get too high. Increases the compression ratio and overworks the compressor.
Your icing problem could be a defrost issue and not a refrigerant charge issue.
Good Luck and hope this gets you started.
Bulbs in door wont last
Hello,
I don't think there is anything wrong with your freezer, maybe the bulb's quality is low that's why it does not last.
Also, the bulb might not last as a result of irregular power supply or power outage.
Either of the above is the reason why the bulbs in your refrigerator won't last.
Take care.
What is the normal operational
why yes there is. Generally speaking, the head pressure should be around the "ambient +30" rule.
That is, measure the entering air temp to the condenser, say 75 degrees. Now add 30 to that and get 105 degrees. Look at a P/T chart and see what the pressure is for that temp which is about 253 for R-404-A.
The evap on a freezer leads the load so, as a general rule, the evap temp is going to be around minus 10 degrees to get a 0 degree box. Coolers are different. So, the pressure for a minus 10 evap is around 25 or so. But the unit has to be close to operating temp. If the box is warm, naturally the pressure is higher. And what influences the pressure is whether or not it's a TXV or a cap tube system.
If a TXV and no receiver, charge by subcooling. If a receiver, fill by sight glass. If Cap tube, charge by superheat.
Hope that answers your question.
Replaced run cap, motor windings ohm out good,
Probably locked rotor. This happens sumetims when the connecting rod breaks or seizes up on the crank shaft. Seperate your power cord ar some point so that you can put an amp meter around just one of the hot wires. It should be 10.2 amps maximum. I think you will see it spike to 25 amps for 2 to 3 seconds when the compressor tries to start. That almost immediately kicks out the overload. This compressor is not rebuildable. so it will require a new one if it is what I think.
How old
May I get the model and serial # to help you find out the year.
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