Bard PA13241-A, PA13361-A, PA13301-A, PA13361-B Adjustments, LOW Ambient Control

ADJUSTABLE DELAY-ON-MAKE AND BREAK TIMER

On a call for compressor operation the delay-on-make period begins which will be 10% of the delay-on-break setting. When the delay-on-make is complete and the high pressure switch (and low pressure switch if employed) is closed, the compressor contactor is energized. Upon shutdown, the delay-on-break timer starts and prevents restart until the delay-on-break and delay-on-make periods have expired.

HIGH PRESSURE SWITCH AND LOCKOUT SEQUENCE (Standard Feature)

If the high pressure switch opens, the compressor contactor will de-energize immediately. The lockout timer will go into a soft lockout and stay in soft lockout until the high pressure switch closes and the delay-on- make time has expired. If the high pressure switch opens again in this same operating cycle the unit will go into manual lockout condition and the alarm circuit will energize. Recycling the wall thermostat resets the manual lockout.

LOW PRESSURE SWITCH, BYPASS, AND LOCKOUT SEQUENCE (Standard Feature)

If the low pressure switch opens for more that 120 seconds, the compressor contactor will de-energize and go into a soft lockout. Regardless the state of the low pressure switch, the contactor will reenergize after the delay-on-make time delay has expired. If the low pressure switch remains open or opens again for longer than 120 seconds the unit will go into manual lockout condition and the alarm circuit will energize. Recycling the wall thermostat resets the manual lockout.

ALARM OUTPUT

Alarm terminal is output connection for applications where alarm signal is desired. This terminal is powered whenever compressor is locked out due to HPC or LPC sequences as described.

NOTE: Both high and low pressure switch controls are inherently automatic reset devices. The high pressure switch and low pressure switch cut out and cut in settings are fixed by specific air conditioner or heat pump unit model. The lockout features, both soft and manual, are a function of the Compressor Control Module.

ADJUSTMENTS

ADJUSTABLE DELAY-ON-MAKE AND DELAY-ON-BREAK TIMER

The potentiometer is used to select Delay-on-Break time from 30 seconds to 5 minutes. Delay-on-Make (DOM) timing on power-up and after power interruptions is equal to 2 minutes plus 10% of Delay-on-Break (DOB) setting:

0.5 minute	(30 seconds)	DOB	= 123 second DOM
1.0 minute	(60 seconds)	DOB	= 126 second DOM

2.0minute (120 seconds) DOB = 132 second DOM

3.0minute (160 seconds) DOB = 138 second DOM

4.0minute (240 seconds) DOB = 144 second DOM

5.0minute (300 seconds) DOB = 150 second DOM

LOW AMBIENT CONTROL

Optional Low Ambient Control

An optional low ambient control is available for both factory and field installed options. The low ambient control is to be applied to the PA13 Series models when operation below 55° outdoor conditions are anticipated. Without this device, the evaporating pressure would fall off, and the indoor coil would ice over.

The fan cycling control cycles the fan motor on, once the liquid refrigerant pressure reaches 350 psig, and off, once it has dropped to 225 psig. It will continue to cycle between these parameters depending on outdoor temperatures and the load/stage of the system.

This cycling maintains a minimum liquid pressure affecting the minimum suction pressure. This effect insures an evaporating temperature that is slightly above the point of ice formation on the evaporator.

This field installed option is Bard Part #CMA-28. See Figure 7.

FIGURE 7

LOW AMBIENT CONTROL WIRING

Manual	2100-467D
Page	17 of 25