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Table 36—Perfect Humidity™ Adaptive Dehumidification System Subcooling Mode Service Analysis
PROBLEM
Subcooling Mode (Liquid Reheat)
Will Not Energize.
Will Not Energize.
Low System Capacity.
Loss of Compressor Superheat
Conditions with Subcooling/Reheat
Dehumidification Coil Energized.
Table 37—Perfect Humidity™ Adaptive Dehumidification System Hot Gas Reheat Mode Service Analysis
PROBLEM
Reheat Mode Will Not Energize.
Loss of Compressor Superheat
Conditions with Subcooling/Reheat
Dehumidification Coil Energized.
Excessive Superheat.
Excessive Superheat.
Demand Control
Demand Control
V
Ventilation (DCV)
til ti
(DCV)
Below set
Below set
High
High
(DCV LED Off)
(DCV LED Off)
(F
(Free Cooling LED Off)
Low
Low
(F
(Free Cooling LED On)
Above set
Above set
High
High
(DCV LED O )
(DCV LED On)
(F
(Free Cooling LED Off)
Low
Low
(Free Cooling LED On)
(F
*For single enthalpy control, the module compares outdoor enthalpy to the ABCD set point.
†Power at N terminal determines Occupied/Unoccupied setting:
**Modulation is based on the supply-air sensor signal.
††Modulation is based on the DCV signal.
***Modulation is based on the greater of DCV and supply-air sensor signals, between minimum position and either maximum position (DCV) or fully open (sup-
ply-air signal).
†††Modulation is based on the greater of DCV and supply-air sensor signals, between closed and either maximum position (DCV) or fully open (supply-air sig-
nal).
CAUSE
No power to control transformer from
evaporator-fan motor.
No power from control transformer to liquid line
solenoid valve.
Liquid line solenoid valve will not operate.
Liquid line solenoid valve will not open.
Low refrigerant charge or frosted evaporator coil.
Thermostatic expansion valve (TXV).
CAUSE
No power to control transformer from
evaporator-fan motor.
No power from control transformer to hot gas
line solenoid valve
Hot gas line solenoid valve will not operate.
Low refrigerant charge or frosted evaporator coil.
Thermostatic expansion valve (TXV).
Liquid line solenoid valve will not operate.
Hot gas line solenoid valve will not close.
Table 38—EconoMi$er IV Input/Output Logic
INPUTS
Enthalpy*
Y1
Y1
Outdoor
Outdoor
Return
Return
Low
Low
On On
C
li
LED Off)
On Off
Off Off
On On
High
High
C
li
LED O )
On Off
Off Off
On On
Low
Low
C
li
LED Off)
On Off
Off Off
High
High
On On
C
li
LED O )
On Off
Off Off
24 vac (Occupied), no power (Unoccupied).
Check power source and evaporator-fan relay. Ensure all
wire connections are tight.
1. Fuse open; check fuse. Ensure continuity of wiring.
2. Low-pressure switch open. Cycle unit off and allow
low-pressure switch to reset. Replace switch if it will
not close.
3. Transformer bad; check transformer.
1. Solenoid coil defective; replace.
2. Solenoid valve stuck open; replace.
Valve is stuck closed; replace valve.
1. Check charge amount. Charge per Fig. 53--- 56.
2. Evaporator coil frosted; check and replace low-pres-
sure switch if necessary.
1. Check TXV bulb mounting, and secure tightly to suc-
tion line.
2. Replace TXV if stuck open or closed.
Check power source and evaporator-fan relay. Ensure all
wire connections are tight.
1. Fuse open; check fuse. Ensure continuity of wiring.
2. Low-pressure switch open. Cycle unit off and allow
low-pressure switch to reset. Replace switch if it will
not close.
3. Transformer bad; check transformer.
1. Solenoid coil defective; replace.
2. Solenoid valve stuck closed; replace.
1. Check charge amount. Charge per Fig. 53--- 56.
2. Evaporator coil frosted; check and replace low-pres-
sure switch if necessary.
1. Check TXV bulb mounting, and secure tightly to suc-
tion line.
2. Replace TXV if stuck open or closed.
Valve is stuck, replace valve.
Valve is stuck; replace valve.
Compressor
Stage Stage
Y2
Y2
1
2
On
On
Minimum position
Minimum position
On
Off
Off
Off
On
Off
Modulating
Modulating** (between min.
position and full-open)
i i
Off
Off
Off
Off
Minimum position
On
On
Modulating†† (between min.
Modulating†† (between min.
position and DCV maximum)
i i
On
Off
Off
Off
On
Off
Modulating***
Modulating
Off
Off
Off
Off
59
REMEDY
REMEDY
OUTPUTS
N Terminal†
Occupied
Unoccupied
Damper
Closed
Closed
(between min.
Modulating** (between
Modulating
d f ll
)
closed and full-open)
l
d
Closed
Modulating†† (between
Modulating†† (between
d DCV
i
)
closed and DCV
l
d
maximum)
maximum)
Modulating†††
Modulating†††
(between
d f ll
)
d DCV
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