7
FORM 145.13-NO2
ISSUE DATE: 1/22/2020
1
Do not run the evaporator fan motor be-
low 30Hz, as coil freeze-up and nuisance
lockouts may occur. The unit is factory set
to minimum 30 Hz output with the excep-
tion of the Low Ambient Condenser VFD,
which is set to 15 Hz.
The unit does not carry a failsafe circuit
to bypass the VFD and run the evaporator
fan in the event of a VFD malfunction.
The unit does not carry a failsafe circuit bypass for the
evaporator fan in the event of a VFD malfunction. Dur-
ing a VFD failure, the evaporator fan becomes non-
operational. If there is a demand for cooling, the unit
compressors continue to run until the low pressure
safety switch trips.
FACTORY SHIPPED
Units that are 8 tons or larger ship with a VFD control-
ler factory installed and wired in the evaporator (air
handler) corner post. See the dimensional drawings in
the IOM for the location.
DSV MODELS
The DSV units ship factory split (condenser and evap-
orator) and require assembly in the field. The motor is
pre-wired to the VFD in the factory.
To assemble the DSV model in the field:
1. Plug the low voltage wiring, shipped wired to the
VFD, to the SE Controller.
2. Connect the low voltage wires from VFD unit
(24VDC) to the evaporator fan VFD relay (EVF-
DR). The EVFDR relay acts as a switch to turn on
the VFD.
3. Connect two 1/4 inch Q.C. to common and nor-
mally open positions (red wire to “C,” orange
wire to “NO”).
The VFD switch runs on 24VDC.
Do not cross 24VAC and 24VDC wiring
on EVFDR relay.
SECTION 1 - INSTALLATION
Do not enter Setup mode when powering
on the VFD.
Do not change parameters 4009 and 4011
for the VAV option on DSH/DSV C-gen
units.
For these units, use the Smart Equipment
(SE) controller to set the VAV setpoint.
Prior to installing or servicing the unit,
ensure proper lockout/tagout (LOTO)
procedures are followed per OSHA
safety regulations (29 CFR 1910.147 and
29 CFR 1910.333). Failure to disconnect
power supply may result in electrical
shock or even death.
Always wait for at least 5 minutes after
disconnecting the power before servicing
the unit.
BACKGROUND
All D-Series and C-Series units that are 8 tons or larg-
er have a Variable Frequency Drive (VFD) installed.
There are 2 Controlled Fan Method VFD options: VAV
differential pressure transducer and discrete speed (3 or
4 speed) fan control.
Refer to the nomenclature breakdown in
the appropriate DSV/DSH Installation,
Operation, and Maintenance (IOM)
manual and also the nameplate of the unit
to determine the Controlled Fan Method.
The tenth digit of the nomenclature (ID
Motor) identifies which method the unit
has.
Use the nomenclature to select the low
ambient condenser option.
For units with the VAV option, the supplied VFD al-
lows the operator to set the external static (0.0–2.5
"WC), as measured from a supply duct location deter-
mined by field installer and/or as per field specifica-
tions. The VFD controls the frequency (speed) of the
evaporator fan motor in order to meet the desired exter-
nal static (ESP) setpoint. The VFD controls amps draw
of the motor and does not allow the motor draw more
than nominal amps.
