Low Ambient Mechanical Cooling Operation (3-25 Ton Units); Evaporator Defrost Control (Edc) Function - Trane ReliaTel Diagnostic Manual

Low Ambient Mechanical Cooling Operation (3-25 Ton
Units)

Evaporator Defrost Control (EDC) Function

The Evaporator Defrost Control (EDC) function provides low ambient cooling, standard, down to
0º F . At this temperature, equipment can provide approximately 60% of the mechanical cooling
capacity. During low ambient operation compressor run time is counted and accumulated by the
RTRM.
Low ambient operation is defined as 55º F for single compressor units, and 40º F for dual
compressor units. Dual condenser fan units provide condenser cycling.
Note: If the outside air sensor fails, the EDC logic is disabled and the #2 condenser fan will run
←
Compressor OFF
←
Indoor Fan OFF
Minutes 0 1
When accumulated compressor run time reaches approximately 10 minutes, an evaporator defrost
cycle is initiated. An evaporator defrost cycle lasts for 3 minutes; this matches the compressor 3
minutes minimum OFF time.
When an evaporator defrost cycle occurs, the compressors are turned off and the indoor fan motor
continues to run. After completing an evaporator defrost cycle, the unit returns to normal
operation, and the compressor run time counter is reset to zero.
Note: Economizer operation is not affected by an evaporator defrost cycle.
132
continuously.
→⏐←
ON (10 minutes accumulated compressor run time)
→⏐←
ON (Continues to run during 3 min.
2 3 4 5
Defrost time)
6 7 8 9 10
→⏐← →⏐ ←
OFF
11 12 13 14 15
→
ON
→
16 17 18
RT-SVD03G-EN