Randell 51000 Series, Operator'S Manual

OM-51000 & 53000 SERIES       15

Troubleshooting

SERVICING THE COMPRESSOR

The compressor is part of the sealed refrigeration system and should be replaced by 

a professional service technician.  You can, however, test the compressor and certain 

components.  Prior to testing, unplug the unit and remove the access cover to the 

mechanical housing.  A small box mounted on the side of the compressor protects the 

relay, overload protector, and capacitor.  Release the wire retaining clip that holds the 

cover in place and slip off the cover and the clip.

To test the compressor relay, pull the relay straight off the compressor without twisting 

or damaging it.  If the relay has an external wire coil, hold the relay so that the word 

TOP is up.  Using a multimeter set at RX1, place the probes on terminals S and M.  The 

multimeter needle should not move.  Remove the probe from terminal M and place it on 

the side terminal marked L.  The multimeter needle should not move.  Remove the probe 

from terminal S and place it on terminal M.  The multimeter needle should sweep across 

the scale, indicating full continuity.  

Turn the relay upside down.  Using a multimeter set at RX1, place the probes on terminals 

S and M.  The multimeter needle should sweep across the scale, indicating full continuity.  

Remove the probe from terminal M and place it on the side terminal marked L.  The 

multimeter needle should sweep across the scale, indicating fully continuity.  Remove the 

probe from terminal S and place it on terminal M.  The multimeter needle should not move.   

If the relay fails any of the tests listed above, the relay is faulty and needs to be replaced.  

Push a new relay onto the compressor terminals and replace the terminal cover.  If the 

relay passes all the tests listed above, proceed to testing of the overload protector.  

To remove the overload protector, use a screwdriver to gently pry open the circular spring 

clip that secures the overload protector to the compressor and snap out the overload 

protector.  Pull the two wire connectors off the terminals.  Using a multimeter set at RX1, 

touch a probe to each overload protector terminal.  The multimeter needle should sweep 

across the scale, indicating full continuity.  If the overload protector passes this test, 

proceed to testing of the compressor.  If the overload protector fails this test, the overload 

protector is faulty and needs to be replaced.  Reattach the push-on connectors to the new 

overload protector, clip it in place on the compressor, and replace the terminal cover.

For testing the compressor, use a multimeter set at RX1 to test each of the three terminal 

pins against each of the other two terminal pins.  Each pair should show continuity.  Then, 

with the multimeter set at RX1000, place one probe against the metal housing of the 

compressor (if necessary, scrape off a small amount of paint to ensure contact with 

bare metal).  Place the other probe on each of the three terminals in turn.  If any of the 

three terminals shows continuity with the housing, the compressor is grounded.  If the 

compressor fails either test, call for service at 888-944-7636.  If the compressor passes 

the tests, reinstall the overload protector, relay, terminal cover, and mechanical housing 

cover.