York SUNLINE 2000 B2CH180 Installation Instructions Manual

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York SUNLINE 2000 B2CH180 Installation Instructions Manual Manual pdf 14 page image

DEFROST SEQUENCE OF OPERATIONThese heat pumps have a unique “ambient modified” time-temperature defrost control that automatically adjusts tochanges in the outdoor temperature. The defrost controlshortens the defrost initiation time periods above 2°C (35°F)and extends the defrost initiation time periods below 2°C (35°F.The control is factory set to defrost at 110 minutes (T3), but itcan be field adjusted to defrost at 80 minutes (T2) or 50 minutes(T1) in areas with high humidity.The curve in Figure 10 shows how defrost initiation times areautomatically compensated for changes in outdoortemperature.EXAMPLE: If the timer is factory set on pin T3 (110 minutes at2°C (35°F) outdoor) and the outdoor temperature climbs to 7°C(45°F), the time initiation cycle decreases to 100 minutes.If the outdoor temperature drops to -12°C (10°F) where ice isless likely to form, the 110 minute interval increses to 150minutes.Two requirements must be met before a defrost cycle can beinitiated.1. The defrost time cycle must be complete.2. The liquid line temperature must be less than -2°C (28°F).Defrost terminates when the liquid line sensor reaches 13°C(55°F) or after 10 minutes. If one or both circuits defrosts,electric heat is energized.The defrost time cycle restarts 10 minutes after the start of thedefrost cycle even though the liquid sensor terminated defrostafter three minutes.During troubleshooting, the defrost time can be reduced to 20seconds by shorting out the SW1 test pegs on the module. Thepegs are 13mm (12 in.) long, 5mm (316 in.) apart and aremounted on a white base. See Figure 11.LOCKOUT CONTROLAny one of four conditions put the system into a lock-outcondition during the heating or cooling mode:1. The discharge line temperature reaches 124°C (255°F)(102°C reset [215°F]) or,2. The discharge pressure reaches 2,786 kPa (398 psig)(2,170 kPa reset [310 psig]) or,3. The suction line freezestat equals -3°C (26°F) (3°C reset[38°F]), or4. The low-pressure cut-out equals 49 kPa (7 psig) (154 kPa[22 psig]).A lock-out energizes the emergency heat light on thethermostat and the red LED light on the unit relay board.Turning the thermostat switch to “off”, then back to “on” willreset the system.NOTICE TO OWNER:If a lockout occurs, check for the following problems beforecalling a serviceman:1. Dirty filters.2. Snow accumulation.3. Leaf or debris blockage.After eliminating the problem, attempt to restart the system asfollows:• turn the system switch on the thermostat to its “OFF”position for 10 seconds.• turn it back to its original position.If the unit doesn't start, call a service man.NOTE: Models with an anti-cycle accessory have a fiveminute delay before restarting.035-18895-000-A-090214 Unitary Products GroupFIG. 10 - DEFROST INITIATION TIMES-23(-10) -17(0)-12(10) -7(20)-1(30) 5(40) 10(50) 16(60)°C (°F)

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