Sequence of Operation, Modes of Operation

SEQUENCE OF OPERATION

MODES OF OPERATION

Cool Only Mode:

•Compressor will modulate from 100% down to 20%.

•Compressor will cycle off if thermostat/controller set- point is reached.

Heat Only Mode:

•Electric heat Stage 1 operates at 1st-stage heating set-point.

•Electric heat Stage 2 (if equipped) operates on 2nd stage (-2F below heating set-point).

Auto Mode:

•Cooling or heating automatically selected based on building temperature vs. thermostat/controller set- points and operates as described above.

CCVC (Continuous Compressor Variable Capacity):

•Compressor will modulate from 100% down to 20%.

•Compressor will not cycle off if thermostat/controller set-point is reached, and would stay running at the 20% minimum capacity.

•If space temperature drops -2F below cooling set-point electric heat Stage 1 will then cycle to maintain that condition.

•If Stage 2 electric heat is installed, and if required, will cycle at -4F below cooling set-point to maintain that condition.

•If CCVC is terminated the controller will revert to Cool or Auto operation.

•CCVC would be an Operating Mode for all applications where continuous run of the compressor is a requirement.

Testing & Troubleshooting Mode CCFC (Continuous Compressor Fixed Capacity):

•This unit must be controlled with the digital thermostat controller supplied with the unit. To test or troubleshoot, change system mode to CCFC. This will ensure unit runs continuously and in full capacity mode. AHRI ratings are based on this mode of operation.

CCFC (Continuous Compressor Fixed Capacity):

•The compressor is turned ON and locked ON as long as the thermostat/controller is in Test Mode 2.

•When in CCFC the compressor does not modulate but will be locked ON at 100% capacity.

•If space temperature drops -2F below cooling set-point electric heat Stage 1 will then cycle to maintain that condition.

•If Stage 2 electric heat is installed, and if required, will cycle at -4F below cooling set-point to maintain that condition.

•If CCFC is terminated the controller will revert to Cool or Auto operation.

•CCFC would not be considered an Operating Mode and should only be used for system testing as required.

Indoor Blower Operation

The indoor blower speed will modulate with the compressor operation from 50% to 100% of operation. Once compressor operation is at 50 or below, percent airflow will be at 50% and no further reduction of

airflow will occur. Modulation is accomplished by modulating a 0-10 volt signal from OUT 7 to the indoor blower control board which then sends a PWM signal to the indoor blower motor.

An additional option to maintain airflow at 100% is also available. This selection is done at the thermostat/ controller under Fan Modes. Default is No for “Always 100%”setting. Change to Yes to disable indoor blower modulation as described above.

2 LED’s are located on the Blower Control Board. The Red LED will light anytime 24V is applied to the board and it is connected to the ECM motor. The Green LED will flash a series of short and long flashes depending on the output from the digital thermostat/controller.

Outdoor Fan Motor Operation

The outdoor fan motor speed is varied in response to outdoor air temperature and pressure. The fan motor will cycle on and off with the compressor when not in a CCVC or CCFC. At all times above 122 degrees OAT, the outdoor fan, OUT 9, will be energized at high speed. From 122 degrees to 55 degrees the outdoor fan, OUT 9, will be set at normal outdoor airflow. Below 55 degrees the outdoor fan will modulate to maintain a 300 psi head pressure. This will act as a low ambient fan cycling control. The output may go to zero output to maintain the 300 PSI. The outdoor ECM motor will be programmed with a minimum RPM allowed to protect the bearing system. Any signal that is less than the percent torque required to maintain the minimum RPM will cause the motor to shut off. Once head pressure rises the motor will restart.

These functions are regulated by the digital thermostat/ controller with input from the pressure transducer and output signal to the Fan Control Board.

2 LED’s are located on the outdoor Fan Control Board. The Red LED is not active and does not light under any condition. The Green LED will flash a series of short and long flashes depending on the output from the digital thermostat/controller.

Capacity Modulation and High Head Pressure Control The pressure transducer monitors the high side pressure providing input to the digital thermostat/controller. It is powered using a 5Vdc power supply with a digital relay signaling the compressor unloader solenoid as required. When the ECU head pressure exceeds 615 PSI based on outdoor and indoor ambient conditions the compressor will automatically start to reduce capacity to stay on-line keeping the pressure at or below 575 PSI. The thermostat/controller display alternates between OD temperature and discharge pressure. When compressor capacity is being reduced due to high pressure conditions it will also indicate “High Head Pressure Control” mode on the display. A separate 650 PSI high pressure cutout switch is also employed as additional safety device. See Compressor Control Module on following page for more details.

Manual	2100-538E
Page	16 of 23