Delay on evap. fan sistm.404a

It sounds like its doing good.

with out a model and serial number to go on, I can tell you that most all of their units have what is called a "Fan Delay" located in the evaporator coil. It keeps the fan off on the evap. to prevent them from circulating warm air and overloading the compressor. In most cases, when the evap. reaches about 20 to 26 degrees, the delay will bring the fans on and will start cooling the conditioned space.
Hope this helps.

Look to the fan delay/defrost terminator that is located inside to the evap. It is usually attached to the evap coil. check there first.

Check to see if there is correct,complete power to the fan. If not, look for a fan delay that may be attached to the evap. It comes in many configurations. It may have two or three wires going to it. They may be two black wire or 3 wire of different colors. Power goes to the fan thru this device. It may not be working or the evap not getting cold enough to activate it. I will need model and serial to help more.
Let me know what you find.

In most cases, there is a device located in or on the evap that senses the temp of the evap. This can be a defrost terminator/fan delay. Sometimes they are separate devices and sometimes they are a 2 in 1 device. If the evap does not get cold enough, the fans will not come on. Usually about +20 degree F. It is to prevent circulating warm air after a defrost and to keep from overloading the compressor after a defrost as heat is generated by electric elements. I would look to see if the defrost terminator / fan delay has malfunctioned, then I would check the refrigeration system performance.

It runs when the compressor runs except when it's in the defrost cycle. If you have an electronic control instead of a defrost timer the control could be the problem since it runs the fans. You can test the evaporator fan. See how here> How to check everything
http://www.acmehowto.com/howto/appliance/refrigerator/refrigerator.php

http://www.truemfg.com/pdf/InstallManuals/T-SERIES/t_series_english.pdf
Go to this web site and look in the manual on page 15. Check "Compressor runs but will not refrigerate". Gives some suggestions.
Now, inside the evap, usually strapped or clipped to the coil "U" turn on the end of the coil, is a Klixon device. This device comes in many different configurations. There may be 1 or 2 of these. One is a defrost termination switch. When evap gets hot enough so no frost is present, it terminates the defrost cycle. The other is a fan delay. It comes on when the coil temp gets to about 20 degrees. This prevents circulating warm air from defrost cycle. Now if there is only one device, it can be 2 in 1. That is, a defrost terminator/ fan delay. Will most likely have 3 wires going to it where as the 2 separate ones will only have 2 wires to each one. Now, either this fan delay is not working correctly or the coil is not getting cold enough. When it gets cold enough, it turns on the evap fans. This is most likely where your problem lays. Check it out.

Most all commercial freezers have some sort of fan delay/ defrost termination device. Commonly called a "Klixon" (pronounced clicks-on). It is a device that is attached to the evap. It's function is to terminate the defrost cycle when the evap reaches a certain temp, say about 50 degrees or so, to ensure there is no build up of frost/ ice on the evap. It then allows the compressor to run, and cool the evap down to a reasonable temp., say about 20 degrees, and then let the evap fan come on. It prevents overloading the compressor during a high temp condition, and it also prevents circulating warm air left from the defrost cycle. I believe this device is most likely your problem. With no air circulating, the box will no cool down.. I have seen them burn and/or slhort internally. They can come apart. too. I would look here for that problem. the True manufacturing website does not give alot of info on this piece of equipment, such as a wiring diagram but manuals are available.
Check this out and let me know how it comes out.

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.

If this is a Bev-Air, don't think the door switch will control the fan. At the evap, there is a temp sensor called a fan delay. When unit goes into defrost mode, this warms up. Some also serve a dual purpose. It will terminate the defrost cycle at a certain temp., say 51 degrees or so, at the evap. Anyway, when unit comes out of defrost, it keeps the fan off so it allows the evap to cool quicker and to prevent circulating warm air. This could be your problem. Not a hard fix but they can be a pain sometimes. Outside chance that the unit is low on refrigerant (freon). This will not let the evap get cold enough to trip the sensor back into position to turn the fan on. Good Luck. Restaurant Parts and More carry alot of Bev-Air stuff. 1-888-814-1110. Ask for Rick