A LOOK AT SERVICE SAFETY
Servicing
61
Step 1: Before Continuing with
Troubleshooting...
WARNING!
All electric power should be disconnected and
you should have already made sure that the compressor does
not have a ground fault (see “Checking for a Ground Fault”
on pages 47-48).
You should have also checked the windings
for continuity and proper resistance (see “Checking for Conti-
nuity and Proper Resistance” on pages 48-49), made sure the
system is getting proper voltage, and that the control, thermo-
stat, and contactor are working properly.
Step 2: Disconnect Fan Motor or Any
Other Devices
If there is a fan motor or any other auxiliary device, open the
circuit for the fan motor or any other device.
Step 3: Check External Thermal
Protector
Check for continuity across the thermal protector. If there is no
continuity, then the thermal protector may be tripped. Wait at
least 5 minutes, then check continuity again. If there is still no
continuity, replace the thermal protector.
Step 4: Check Wiring
Confirm that there is continuity between:
a. The power input terminal on the thermal protector and
5 on relay.
b. The protector common lead wire and C.
Step 5: Check Potential Relay
Before checking the relay, be sure it is mounted at the proper
position. (See pages 28-32.) Check the potential relay by mea-
suring continuity between:
a. Relay terminals 5 and 2. If there is no continuity, replace
the relay.
b. Relay terminals 2 and 1. If there is no continuity, then
the contacts are open. Replace the relay.
Possible reasons that a relay is not working properly include:
•
Use of incorrect relay. Replace with correct relay.
•
Line voltage is too high or low (greater than 110% or
less than 90% of rated voltage).
•
Excessive short cycling. Short cycling can be caused by
problems with the compressor’s thermal protector or sys-
tem components such as the thermostat, control, contac-
tor, or high or low pressure cut-out. For more information
on troubleshooting the thermal protector, see Step 3. For
troubleshooting the system components, refer to the OEM
service information.
•
Vibration due to loose relay mounting. Tighten relay
mounting.
•
Use of incorrect run capacitor. Replace with proper run
capacitor.