Sterling RT - Manual (Page 23)

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PROBLEM PROBABLE CAUSE SOLUTION
2. CFM Low Filters Dirty or clogged.
Insuffi cient Air Flow Coil - DX or Chilled Water Dirty or clogged.
Obstructions in High Velocity Air Stream a. Obstruction near unit outlet.
b. Sharp elbows near unit outlet.
c. Improperly designed turning vanes.
d. Projections, dampers or other obstructions in part
of duct system where air velocity is high.
3. CFM High - System a. Oversized duct work.
Too Much Air Flow b. Access door open.
c. Registers or grilles not installed.
d. Filters not in place.
e. System resistance lower than anticipated.
Blower Blower RPM is too great.
4. Blower Does Not Operate Installation a. Incorrect electrical connection.
b. Wrong voltage.
c. Blown fuse.
Unit a. Broken belt(s).
b. Loose pulleys.
c. Power to unit is disconnected.
d. Motor overload protector has broken circuit.
e. Optional thermostats, fi restats, freezestats may
lockout blower operation if set incorrect.
TROUBLESHOOTING GUIDE – ELECTRIC MOTORS
PROBLEM PROBABLE CAUSE SOLUTION
1. Motor Blown fuse or open circuit breaker. Replace fuse or reset circuit breaker.
Overload trip. Check and reset, if manual.
Improper line connections. Check connections to unit wiring diagram.
Improper current supply. Check to determine that power supply agrees with
motor nameplate specifi cations.
Mechanical failure. Determine that motor and drive turn freely.
Check bearings.
Motor overloaded. Reduce load or replace motor.
With a 3 phase power source, one Check line for open phase.
phase may be open.
Defective capacitor. Replace capacitor.
2. Motor Stalls Wrong application. Consult manufacturer.
Overloaded motor. Reduce load or replace motor.
Low line voltage. Check across AC line and correct
if possible.