Installation
CAUTION
Do not enter Setup mode when powering on the VFD.
Do not change parameters 4009 and 4011 for the VAV option on DSH, DSV, or CSV C-gen units. These 2
parameters are used for B-gen units only (Simplicity 1A not SEC.)
For these units, use the Smart Equipment (SE) controller to set the VAV setpoint.
WARNING
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 larger have a Variable Frequency Drive (VFD)
installed.
There are 2 controlled fan method VFD options for D-series. SZVAV differential pressure transducer
and IntelliSpeed™ (2, 3 or 4 speed) fan control.
There are 3 controlled fan method VFD options for C-series. SZVAV, MZVAV differential pressure
transducer and IntelliSpeed™ (2 speed) fan control.
Note:
Refer to the nomenclature breakdown in the appropriate DSV, DSH, or CSV 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.
SZVAV option in D-Series / MZVAV option in C-Series
For C/D-Series units with the SZVAV or MZVAV option, the supplied VFD allows the operator to
set the external static (0.0–5.0 "WC), as measured from a supply duct location determined by
field installer and/or as per field specifications. The VFD controls the frequency (speed) of the
evaporator fan motor in order to meet the desired external static (ESP) setpoint. The VFD controls
amp draw of the motor and does not allow the motor draw more than FLA amps.
Note:
Do not run the evaporator fan motor below 30Hz, as coil freeze-up and nuisance
lockouts may occur. The unit is factory set to minimum 30 Hz output with the exception of the
Low Ambient Condenser VFD, which is set to 15 Hz.
Note:
The unit does not carry a failsafe circuit to bypass the VFD and run the evaporator fan in
the event of a VFD malfunction.
VFD for D-Series (DSV/DSH) Air-cooled Self-Contained Units, and C-Series (CSV) Water-Cooled Self-Contained Units,
C-Gen
8
Johnson Controls
