Carrier® Low Ambient Control Kit Accessory

FEATURES

The head pressure control kit regulates outdoor (condenser) fan speed during cooling mode operation. A temperature sensor mounted on a return bend of the outdoor (condenser) coil controls the speed of approved outdoor fan motors in order to maintain a constant head pressure in the outdoor coil.

When properly installed, the control will maintain the appropriate head pressure at low ambient temperatures between 40°F (4.4°C) and 0°F (–17.8°C). The controller will not be activated until the outside air temperature is below 60°F (15.5°C). The unit without the low ambient kit is rated for 40°F (4.4°C) outside air.

The controller is designed to apply full voltage to the motor with probe temperatures above 100°F (37.8°C) or if the outside air is above 60°F (15.5°C). With probe temperatures between 100°F (37.8°C) and 70°F (21.1°C) and outdoor air below 60°F (15.5°C), the motor speed is proportional to the probe temperature. As the temperature being sensed decreases, the output voltage decreases. With probe temperature below 70°F (21.1°C), the motor will re- main off. If the cut-out speed knob is not set to minimum, the motor may cut out sooner and at a higher probe temperature than 70°F (21.1°C), limiting the motor’s modulation range. Once the probe temperature increases above 70°F (21.1°C), the motor will restart to the hard start knob setting. The hard start setting allows the motor to begin at a higher RPM upon restart than the RPM corresponding to the probe’s temperature. This avoids low RPMs of the condenser motor.

The head pressure control kit in this application is only to be used with an approved condenser motor. The hard start knob setting and the cut-out speed knob are to be set to minimum for proper functionality.

On 575-v units, the 575-v factory-installed outdoor (condenser) motor is replaced with a 460-v approved fan motor. This is powered through an Auto-transformer (buck boost) to convert 575-v to 460-v and uses the 460-v connection on the controller. Follow these instructions to installing the motors and head pressure controller. See the additional transformer kit instructions for transformer installation. Refer to Kit CRTRXKIT003A00 accessory for details on installation.

INCLUDES