MK/MV – Medium Profile Series Unit Coolers (E206993_M)
54
10
START UP
10.1
PRE-STARTUP
After the installation is completed, a review of the following items should be performed before
the system is placed into operation:
Check electrical connections, fan blade set screws, fan motors, guards, and all other fasteners
for tightness. Be sure the thermostatic expansion valve bulb is properly located, strapped
and insulated.
With the system operating, check the supply voltage. It must be /- 10% of the voltage
marked on the unit nameplate.
For electric defrost systems check the defrost timer to see that is set for the correct time of day
and the starting pins have been installed (normally two per day). The defrost should be scheduled
for times when the freezer doors are not likely to be open.
When the system is first started up, the box temperature is typically above the opening
temperature of the fan delay thermostat. The fans may remain off for a lengthy period of time.
To prevent this it is permissible to install a temporary jumper wire between terminals “F” and
“B” or “N” and “B” depending on the unit wiring arrangement. Once the box temperature is
below +25
°
F the jumper wire should be removed.
10.2
OPERATION CHECKOUT
Check the room thermostat setting. Be sure it functions properly.
After the system has balanced out at the desired room temperature check the operation of the
expansion valve by properly measuring the superheat at the sensing bulb. Refer to section 4.6
for making expansion valve adjustments. As much as 30 minutes may be required for the new
balance to take place after an adjustment is made.
On electric defrost systems once the coil is frosted, manually advance the defrost timer to initiate
a defrost. Observe the defrost cycle to see if all controls are functioning properly and that the coil
is clear of all frost before the system returns to refrigeration. Reset the defrost timer to the
correct time of day.
A defrost cycle is only needed when the frost build up is such that it impedes the airflow through
the coil. The defrost requirements will vary on each installation and may change depending on
the time of the year and other conditions.
