Classic HVPA & HVPSA M&S 8.09-1
15700 - 13
HVAC Equipment
6.1 TROUBLESHOOTING
In diagnosing common faults in the heat pump system, develop a logical thought
pattern as used by experienced technicians. The charts which follow are not intended
to be an answer to all problems but only to guide the technician’s thinking. Through
a series of yes and no answers, follow the logical path to a likely conclusion.
A novice technician should use these charts like a road map. Remember that the
chart should clarify a logical path to the problem’s solutions.
Electrical Checks Flow Chart
Unit Running?
NO
YES
Thermostat Problem?
Go to Mechanical Check
for Cooling or Heating
YES - Repair and Recheck
NO
Transformer Problem?
YES - Repair and Recheck
NO
Voltage on Compressor Side of Contactor?
YES
NO
Run Capacitor
Voltage on Line Side of Contactor?
Compressor Internal
Overload Open
NO
YES
Compressor Winding
Open
Circuit Breakers or
Fuses Open
Compressor Contactor
Unit Wiring and
Connections
YES
High Pressure Cut-Out
Compressor Winding
Grounded
Low Pressure Cut-Out
Outdoor Fan Motor
Grounded
Compressor Time
Delay
Grounded Capacitor
Unit Wiring and
Connections
Replace Fuses or
Reset Breakers and
Recheck System
fan always starts after the compressor, and it will cycle frequently during normal
operation at low outdoor conditions.
Q.
Compressor Time Delay.
The time delay module (delay on make) prevents the
compressor from restarting immediately after interruption of power. The delay
interval, which is adjustable from .2 to 8 minutes, protects the compressor by
allowing internal refrigerant pressures to equalize. The time delay does not effect the
electric heat circuit.
