Because the pressure switches are monitored only when "Y1"
(Input) is active, the code for pressure switch open will not be
seen when "Y1" is off. Instead, the "Normal Operation" or
"Short Cycle Lockout" code will be seen.
When a pressure switch opens and causes a short cycle
lockout, the pressure switch-open code will be seen until it
closes, then the short cycle lockout code will flash unless it
has already expired.
Electrical Shock Hazard
Disconnect power before servicing.
Replace all parts and panels before operating.
Failure to do so can result in death or electrical shock.
1. Disconnect power.
2. Remove the heater compartment access panel.
3. Reconnect power and set thermostat for heating operation.
4. Observe LEDs and compare to Defrost Control Board
Diagnostic LEDs chart.
5. If a system failure is indicated, take appropriate action to
6. Turn off thermostat and disconnect power.
7. Replace the heater compartment access panel.
8. Reconnect power.
Circulating Air Blower (PSC Motor)
The circulating air blower is controlled by a timing circuit in the
blower control. Timings are not adjustable.
There is no blower "on" delay after a call for heating or cooling.
Blower "off" delay is 90 seconds after the thermostat is satisfied.
NOTE: No blower speed adjustments are required.
Blower Speed Chart (PSC Motor)
for Heat Pump and Cooling Only Models
Factory shipped Settings
Circulating Air Blower (Variable Speed Motor)
Packaged units equipped with a variable speed circulation air
blower motor will deliver a constant airflow within a wide range of
external static pressures.
The variable speed motor will slowly ramp up to normal operating
speed. This minimizes noise and increases comfort by
eliminating the initial blasts of air encountered with standard
motors. At the end of a cooling or heating cycle, the motor will
slowly ramp down.