Thermo King T-500R Maintenance Manual page 267

Condition
Contact Chatter
Contact welding or freezing
Battery is not recharging
Possible Cause
Low line voltage or no voltage on
one leg
Low battery voltage
Defective or incorrect coil
Poor contact in control circuit
Abnormal in-rush of current
Low voltage
Foreign matter prevents contacts
from closing
Rapid cycling
Short circuit
Loose alternator belt
Loose connections in electrical
system
Worn brushes in alternator
Voltage regulator faulty
Battery defective
Alternator defective
Dirty battery terminals
Electric Standby Diagnosis
Remedy
Bring voltage up to within 10% of
motor rating
Check voltage condition. Check
momentary voltage dip during
starting—low voltage prevents
magnet sealing
Replace coil
Check auxiliary switch contacts and
overload relay contacts. Check for
loose connections in control circuits
Check or grounds, shorts or
excessive motor load current
Correct voltage condition. Check
momentary voltage dip during
starting
Clean contacts
Check for cause of short cycling
(such as thermostat)
Correct fault
Tighten belt
Check all electrical connections and
charging system
Repair
Replace
Replace
Repair or replace
Clean and retighten
14-3