|
1.
High head pressure and high back pressure |
|
Cause |
Solution |
|
Condenser coil clogged or restricted |
Clean condenser coil or remove restriction |
|
Condenser fan motor inoperative |
Repair or replace defective fan motor |
|
Air in system |
Reclaim refrigerant, pull vacuum, recharge system
with correct refrigerant and proper amount |
|
Refrigerant overcharged |
Reclaim refrigerant, pull vacuum, recharge system
with correct refrigerant and proper amount |
|
Back
to top |
|
|
|
2.
Low back pressure and low head pressure |
|
Cause |
Solution |
|
Capillary tube restriction |
Reclaim refrigerant, verify restriction, replace
capillary tube if necessary, pull vacuum, recharge
system with correct refrigerant and proper amount |
|
Refrigerant undercharged |
Reclaim refrigerant, pressurize cabinet with
nitrogen, check for leaks and repair if leak is
found, pull vacuum, recharge system with correct
refrigerant and proper amount |
|
Leak in system |
Reclaim refrigerant, pressurize cabinet with
nitrogen, check for leaks and repair if leak is
found, pull vacuum, recharge system with correct
refrigerant and proper amount |
|
Back
to top |
|
|
|
3.
Pressures normal but cabinet is warm |
|
Cause |
Solution |
|
Refrigerant undercharged |
Reclaim refrigerant, pressurize cabinet with
nitrogen, check for leaks and repair if leak is
found, pull vacuum, recharge system with correct
refrigerant and proper amount |
|
Control set too warm |
Reprogram control per equipment operation &
maintenance manual |
|
Evaporator fans not running |
Evaporator fan will not run above +35°F coil
temperature on electronic control units. If coil is
cold check wiring to evaporator fans. |
|
Back
to top |
| |
|
4. Compressor
starts and runs but cycles on overload |
|
Cause |
Solution |
|
Low voltage |
Check voltage at unit contactor with compressor off.
Voltage must be 197 or more & the voltage must stay
above 187 when the compressor tries to start. |
|
Overload protector defective |
Check to see if contacts are closed when cool. If
not, replace. |
|
High head pressure |
See #1 |
|
Back
to top |
| |
|
5.
Compressor will not
start – hums, but cycles on overload |
|
Cause |
Solution |
|
Low voltage |
See #4 |
|
Relay and/or capacitors defective |
Equalize high to low side pressures through gauge
set. If compressor starts, run capacitor is good
but start relay or start capacitor is bad. |
|
Overload defective |
See #4 |
|
High head pressure |
See #1 |
|
Back
to top |
| |
|
|
6. Cabinet
sweating |
|
Cause |
Solution |
|
High ambient humidity |
Check store condition 55% relative humidity or less,
wet bulb temperature 57°F or less. |
|
Defective door heater |
Check for open or shorted circuit. Replace if
necessary. |
|
Back
to top |
| |
|
7.
Unit randomly trips
circuit breaker or blows fuses |
|
Cause |
Solution |
|
Low voltage |
See #4 |
|
Defective breaker or fuse |
Check to see if recommended hack type breaker or
time delay fuses are used. |
|
Branch circuit wire gauge too small for unit |
See voltage drop chart for recommended wire gauge
size. |
|
Back
to top |
| |
|
8.
Low voltage at
unit contactor |
|
Cause |
Solution |
|
Supply voltage too low |
Install buck-boost transformer |
|
Supply voltage too low only when compressor tries to
start. |
Branch circuit wire gauge too small. Install
larger gauge wire.
See voltage chart. |
|
Back
to top |
| |
|
| |
|
