Service manual

8
SERVICE INSTRUCTIONS
1. High head pressure and high back pressure:
A. Condenser coil clogged or restricted
B. Condenser fan motor defective.
C. Air discharge in rear of cabinet restricted.
2. Low back pressure and low head pressure:
A. Restriction in system.
B. Refrigerant undercharged.
C. Leak in system
3. Pressure normal – cabinet warm:
A. Coil blocked with frost.
B. Refrigerant undercharged.
C. Control set too warm.
4. Cabinet not cycling – coil blocked with frost:
A. Defective temperature controller, or improper
settings.
B. Refrigerant overcharged.
C. Location too hot.
D. Condenser clogged.
E. Condenser fan motor defective.
F. For freezer, defrost heater not operating.
G. Air leakage into cabinet due to open door or faulty
door seal.
5. Compressor starts and runs – but cycles on overload:
A. Low voltage
B. Relay defective.
C. Overload defective.
D. High head pressure (see #1
TROUBLE SHOOTING
Symptom-System Operates Long or Continuously
POSSIBLE PROBLEM POSIBLE CAUSE REMEMDY
How Long do the doors stay open? Door closer need adjust. Adjust door closer and keep doors closed.
Is the condenser clean? Dirty condenser. Clean condenser
Are the condenser fans running? Fans not running. Repair or replace
Is the evaporator dirty or iced up? Iced or plugged evaporator coil(s). Defrost or clean (check control settings)
Are the evaporator fans running? Fans not running. Repair or replace
have you checked the refrigerant level? Shortage of refrigerant. Repair leak and recharge.
Is there air or other non-
condensables in
Non-condensables in the system Evacuate and recharge.
the system?
Are all controls functioning properly? Control contacts or error codes. Repair or adjust the control.
Checked expansion valve for Freezers? Improper controls adjusted. Clean or replace.
What is Evaporator Superheat? Evaporator Superheat too high. Adjust expansion valve to lower
Superheat setting.
Where is condensing Unit located? Location too warm.
Ventilate area or change to cooler
Air leaks or doors location.
Is Box well sealed from air penetrations? Wall panels not locked or wall Seal leaks, and adjust doors or
pentrations not sealed. replace.
Is system capacity sufficient for product Product load greater than system Sevice the units or replace.
load? capacity.
CHECK LIST
A. Check operating pressures.
B. Check electrical requirements of unit to supply voltage.
C. Set temperature control for desired temperature range.
D. Check sight glass (if applicable) for proper refrigerant charge.
E. Check system for proper defrost settings and operation.
F. Check condensing unit for vibrating or rubbing tubing. Dampen and clamp as required.
G. All valves should be completely opened counter-clockwise.
H. Check packing nuts on all service valves.
I. Replace all service valve caps and latch unit covers.