Follett FZR Series - Manual (Page 11)

Refrigeration system
The FZR series -20 C (-4 F) freezer refrigeration system is designed to give many years of trouble-free service.
Except for routine cleaning of the air-cooled condenser and related parts, the refrigeration system requires no
service or maintenance. The system uses a thermostatic expansion valve and is critically charged. Access fi ttings
are provided for ease of service. However, the connection of refrigeration service hoses to the fi ttings will almost
invariably result in a signifi cant change in the system charge. This change can adversely affect the performance
of your freezer. Therefore, Follett recommends that if hoses are ever connected to the refrigeration system for
service, the refrigerant should be recovered, the system evacuated, and recharged by weighing in the correct
refrigerant charge.
Note: Do not charge the system by pressures.
Checking refrigeration system pressures
1. Remove the rear access panel (Fig. 10).
2. Turn the power switch to the on position.
3. Following the instructions on page 6 verify that the temperature controller is set to the original factory
cut-in setting of -23 C (-9 F).
4. Allow the freezer to operate and stabilize at least 60 minutes, verifying the cut-out temperature is
being reached.
5. Connect refrigerant hoses to access fi ttings and measure air temperature at condenser intake grille.
6. Verify correct pressures with the temperature chart below.
7. Troubleshoot refrigeration system as needed.
Note: Do not attempt to obtain correct refrigeration pressures by adjusting the system charge.
11
Condenser inlet air temperature 70 F 80 F 90 F 100 F
Discharge pressure (psi) 197 225 255 285
Suction pressure (psi) 12 13 14 15
DRYER
HIGH PRESSURE VAPOR LOW PRESSURE VAPOR HIGH PRESSURE LIQUID LOW PRESSURE LIQUID
COMPRESSOR
FA
N
10oz. Charge
High Psi
Liquid
Low Psi
Liquid
High Psi
Vapor
Low Psi
Vapor
HEAT EXCHANGE
E
V
APORA
T
OR F
A
N
EVAPORATOR/DEFROST UNIT CONDENSING UNIT
DEFROST HEA
T
ER
E
V
APORA
T
OR
TXV
LOW SIDE
SERVICE PORT
HIGH SIDE
SERVICE PORT
Refrigeration system diagram