Operation - Johnson Controls MR4PMUHV Manual

Federal Communications Commission
(FCC) Compliance Statement
This equipment has been tested and found to
comply with the limits for a Class A digital device
pursuant to Part 15 of the FCC Rules. These limits
are designed to provide reasonable protection
against harmful interference when the equipment is
operated in a commercial environment. This
equipment generates, uses, and can radiate radio
frequency energy and, if not installed and used in
accordance with the instruction manual, may cause
harmful interference to radio communications.
Operation of this equipment in a residential area is
likely to cause harmful interference, in which case
the user is required to correct the interference at
his/her own expense.
Canadian Compliance Statement
This digital apparatus does not exceed the Class A
limits for radio noise emissions from digital
apparatus set out in the Radio Interference
Regulations of the Canadian Department of
Communications.
Application
IMPORTANT: The MR4PMUHV
Temperature/Defrost Control is intended to control
equipment under normal operating conditions.
Where failure or malfunction of the
MR4PMUHV control could lead to an abnormal
operating condition that could cause personal
injury or damage to the equipment or other
property, other devices (limit or safety controls) or
systems (alarm or supervisory systems) intended
to warn of, or protect against, failure or malfunction
of the MR4PMUHV control must be incorporated
into and maintained as part of the control system.
The MR4PMUHV Temperature/Defrost Control
consolidates the functions of a temperature control,
a digital temperature readout, a defrost cycle timer,
and a defrost termination device.
The MR4PMUHV control provides direct control in
many refrigeration applications. See electrical
ratings in Tables 6 through 8 for more information.
2 MR4PMUHV Electronic Temperature/Defrost Control with Relay Pack Product/Technical Bulletin

Operation

The MR4PMUHV Control performs the following
functions:
Temperature Management
Several settings define the temperature control
functions:

Setpoint and Differential settings establish the
controlled temperature and acceptable temperature
range.

Cycle Delay establishes a set time interval between
compressor restarts to avoid excessive cycling.

Deep Freeze Time establishes the duration of a
manually-initiated freeze cycle.

Sensor Failure Operation initiates a predefined
response to a temperature sensor failure.
Alarm Management
Several settings define the control functions for alarms:

High and Low Temperature Alarms provide
notification of temperatures that exceed
user-designated high and low limits.

Alarm Time Delay keeps short-duration
temperature changes from triggering an alarm.

Alarm Differential keeps the alarm from cycling
rapidly on and off due to minor temperature
fluctuations.

Alarm Codes assist in troubleshooting.
Defrost Cycle Management
The MR4PMUHV Temperature/Defrost Control allows a
hot gas or electric heat defrost cycle, and uses time or
temperature to control defrost termination.
Evaporator Fan Management
These settings define the control functions for
evaporator fans:

Fan Operating Mode controls whether evaporator
fans run continuously or only when the compressor
is on.

Fan Start-Up Delay follows either time-based or
evaporator-temperature-based startup after defrost.
In a timed-defrost application, a properly-wired
reversible fan motor can run in reverse, bringing
warm air over the evaporator coils.