Repair manual

Troubleshooting – Refrigerant Compressor
Webasto Product N.A., Inc. 30 www.techwebasto.com
™
6.3 Troubleshooting Table – Refrigerant
Compressor and Related Components
This section provides information to assist service
personnel in identifying compressor problems. It
provides a general troubleshooting table that relates
complaints or problems to possible causes and solutions.
This section also provides greater detail about specific
compressor problems.
For your safety, read and follow the “General Service and
Safety Precautions Concerning Refrigeration
Compressors” on page 26.
This Troubleshooting Table is not designed to replace the
training required for a professional air conditioning/
refrigeration service person, nor is it comprehensive.
Table 9. Troubleshooting Table – Refrigerant Compressor and Related Components
Symptom Possible Causes Remedy
Compressor will not start –
no audible hum
Thermal protector not working properly. See “Identifying Compressor Electrical Problems”
on page 31.
Wiring improper or loose. Check against wiring diagram and wire properly.
Compressor motor has a ground fault (also known as a short
circuit to ground).
See “Identifying Compressor Electrical Problems”
on page 31.
Compressor will not start –
hums but trips on thermal
protector
Improperly wired. Check against wiring diagram and wire properly.
Low voltage to compressor. Turn off system until proper voltage is restored.
Compressor electrical problems:
a. Compressor motor has a winding open or shorted.
b. Start capacitor not working properly.
c. Relay does not close.
See “Identifying Compressor Electrical Problems”
on page 31.
Same as “a”.
Same as “a”.
Internal mechanical troubles in compressor. See “Checking for Adequate Compressor
Pumping” on page 35.
Compressor starts, but
does not switch off of start
winding
Improperly wired. Check against wiring diagram and wire properly.
Low voltage to compressor. Turn off system until proper voltage is restored.
Compressor electrical problems:
a. Compressor motor has a winding open or shorted.
b. Relay failing to open.
c. Run capacitor not working properly.
See “Identifying Compressor Electrical Problems”
on page 31.
Same as “a”.
Same as “a”.
Discharge pressure too high.
Internal mechanical trouble in compressor. See “Checking for Adequate Compressor
Pumping” on page 35.
Compressor starts and
runs, but short cycles on
thermal protector
Too much current passing through thermal protector:
a. Extra sources of current draw.
b. Compressor motor has winding shorted.
Check for extra sources of current passing through
thermal protector, such as fan motors, pumps. (This
would be extremely rare as the BCT system is not
designed for such use.)
See “Identifying Compressor Electrical Problems”
on page 31.
Low voltage to compressor. Turn off system until proper voltage is restored.
Compressor electrical problems, such as thermal protector or
run capacitor not working properly.
See “Identifying Compressor Electrical Problems”
on page 31.
Discharge pressure too high.
Suction pressure too high.
Return gas too warm. Check condenser fan for malfunction