How to troubleshoot fan delay - True 49 cu. ft. / 1388 liter Commercial Freezer GDM-49F-RC

yes

do you have just fan delay or fan delay / defrost temination?

The defrost termination/ fan delay control is a temperature-activated, single pole-double throw switch. ).
The control is wired into the refrigeration circuit. The control is located high on the evaporator where the frost is likely to clear last. The function of this temperature-activated switch is to terminate defrost when the evaporator coil has been defrosted, and to delay the evaporator fans from coming on immediately after defrost.
The coil must reach a temperature of 25* F. for the fan delay to close allowing the fans to operate.

Coil must be cold enough for the fan delay to turn fans on. If it is and no fans replace delay

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.

Most all commercial freezers like yours have, what is called, a fan delay. It is located in the evaporator case and is usually attached on or very close to the actual cooling coil. It may also be a combination switch known as a defrost terminator/ fan delay. It's purpose is to keep from circulating warm air. If the cooling coil does not reach a preset temp, the fans do not come one. Another thing is that the fan motor may just be bad. If you have more than one fan, then chances are that it's going to be the fan delay. I would start there to see that either the fan delay switch is bad or there is a reason that the coil is not getting cold enough to activate the switch.

most freezers have 2 controls. 1 is a defrost terminator and the other is a fan delay. the delay and the defrost terminator can sometimes be a "2 in 1" type switch. you would have to study the wiring diagram. The delay will not let the fans come on untill the evap reaches a preset temperature. take another look at the diagram. It may be that the evap is not getting cold enough. you may have a refrigeration issue.

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.

There are three main reasons the fans would not come on.
1: A bad door switch. There are switches on the top part of door frame. They turn fans off when door is opened to prevent warm air from being drawn into unit when door is open. If a switch goes bad the fans will never turn on.
2: Refrigeration problem. The fans are tied into a temperature switch called a fan delay. The fans will not come on until the coil is well below freezing. This is to prevent water spray after a defrost. If unit is low on gas or has any other cooling issue the fans will not come on.
3: Bad fan delay switch. If the fan delay switch becomes "stuck open" the fans will not be energized.

Feel the back of your evaporator coil, if it is very cold and frosted you probably have a bad fan switch, or a bad door switch. ;)

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.