Bard K36A2-A Installation Instructions Manual

Contents

Manual 2100-628Page 18 of 24SEQUENCE OF OPERATIONCOOLING – Circuit R-Y makes at thermostat pullingin compressor contactor, starting the compressor andoutdoor motor. (See NOTE on previous page underCondenser Fan Operation if equipped with Low AmbientControl.) The G (indoor motor) circuit is automaticallycompleted by the thermostat on any call for coolingoperation or can be energized by manual fan switchon subbase for constant air circulation. On a call forheating, circuit R-W1 make at the thermostat pulling inheat contactor for the strip heat and blower operation.On a call for second stage heat, R-W2 makes bringingon second heat contactor, if so equipped.COMPRESSOR CONTROL MODULEThe compressor control module is standard on allmodels covered by this manual. The compressorcontrol module is an anti-short cycle/lockout timer withhigh and low pressure switch monitoring and alarmrelay output.Adjustable Delay On Make And Break TimerOn initial power up or anytime power is interrupted tothe unit, the delay on make period begins, which willbe 2 minutes plus 10% of the delay on break setting.When the delay on make is complete and the highpressure switch and low pressure switch is closed, thecompressor contactor is energized. Upon shutdown,the delay on break timer starts and prevents restartuntil the delay on break and delay on make periodshave expired.During routine operation of the unit with no powerinterruptions, the compressor will operate on demandwith no delay.High Pressure Switch and Lockout SequenceIf the high pressure switch opens, the compressorcontactor will de-energize immediately. The lockouttimer will go into a soft lockout and stay in soft lockoutuntil the high pressure switch closes and the delay onbreak time has expired. If the high pressure switchopens again in this same operating cycle, the unit willgo into manual lockout condition and the alarm relaycircuit will energize. Recycling the wall thermostatresets the manual lockout.Low Pressure Switch, Bypass, and Lockout SequenceIf the low pressure switch opens for more than 120seconds, the compressor contactor will de-energizeand go into a soft lockout. Regardless the state of thelow pressure switch, the contactor will reenergize afterthe delay on make time delay has expired. If the lowpressure switch remains open, or opens again for longerthan 120 seconds, the unit will go into manual lockoutcondition and the alarm relay circuit will energize.Recycling the wall thermostat resets the manuallockout.Alarm Relay OutputAlarm terminal is output connection for applicationswhere alarm relay is employed. This terminal ispowered whenever the compressor is locked out due toHPC or LPC sequences as described.NOTE: Both high and low pressure switch controls areinherently automatic reset devices. The highpressure switch and low pressure switch cutout and cut in settings are fixed by specific airconditioner unit model. The lockout features,both soft and manual, are a function of theCompressor Control Module.ADJUSTMENTSAdjustable Delay on Make and Delay on Break TimerThe potentiometer is used to select Delay on Breaktime from 30 seconds to 5 minutes. Delay onMake (DOM) timing on power-up and after powerinterruptions is equal to 2 minutes plus 10% of Delayon Break (DOB) setting:0.5 minute (30 seconds) DOB = 123 second DOM1.0 minute (60 seconds) DOB = 126 second DOM2.0 minute (120 seconds) DOB = 132 second DOM3.0 minute (180 seconds) DOB = 138 second DOM4.0 minute (240 seconds) DOB = 144 second DOM5.0 minute (300 seconds) DOB = 150 second DOMDuring routine operation of the unit with no powerinterruptions, the compressor will operate on demandwith no delay.Typical Settings for Dual Unit Installation:Unit 1: DOB set at 2 minutes; DOM is 132 secondsUnit 2: DOB set at 4 minutes; DOM is 144 secondsPRESSURE SERVICE PORTSHigh and low pressure service ports are installed onall units so that the system operating pressures can beobserved. A cooling pressure table can be found onpage 22.