York SUNLINE 2000 Installation Manual

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66396-YIM-C-100430 Unitary Products Group(DC). If its ASCD timer is satisfied the UCB will ener-gize compressor #1 and #2 contactor M1. After a twosecond delay, it then energizes compressor #3 and #4contactor M2. Therefore, on a call for heat from W1,both sets of compressors are always energized, unlessone or the other is locked out by the UCB. Also on thecall for heat, the DC energizes the M4 and M5 contac-tor, which brings on both condenser fans.Take note that the MV terminal on the UCB is con-stantly monitored while there is a demand for heat. Ifthe UCB does not see 24vac at terminal MV after sixminutes, it initiates a fault code 9, indicating a heatingproblem.As mentioned earlier, the defrost control (DC) utilizes atime/temperature defrost scheme. The following twoconditions must be met before the DC will enter adefrost mode:1. The DC must first satisfy its accumulated minimumrun time. This is factory set at 60 minutes, but isfield adjustable to 30, 60 or 90 minutes.2. Either of the two defrost thermostats (DF1 or DF2)must be closed. These normally open thermostatsare mounted on the respective liquid lines and areset to close at -1°C (31°F).If neither defrost thermostat is closed at the completionof it’s minimum accumulated run time cycle, the DC ini-tiates another run time cycle, which it must completebefore it looks at the position of the defrost thermo-stats. This action is repeated until, at the completion ofa run time cycle, one of the defrost thermostats isfound to be closed and the DC enters defrost mode.When the DC enters the defrost mode, it’s on-boarddefrost relay is powered. This energizes both reversingvalves, de-energizes both condenser fan motors andenergizes the unit’s optional electric heater. The DCremains in defrost mode until either of the following twoconditions is met:1. Both of the liquid line thermostats are open. Eachis set to open at 13°C (55°F).2. The maximum defrost run time of 10 minutes is met.The DC also contains a set of test pins. Placing ajumper across these pins will result in the followingactions:• If the ASCD timer is active, it is now by-passed,allowing the compressor to run.• If the DC is in a lockout condition, the lockout isreset.• If the compressor is running, the DC is forced intodefrost mode. The control will remain in defrostmode for as long as the jumper is in place. Whenthe jumper is removed, the control will terminatethe defrost mode in the normal manor as describedabove.NOTE: The DC has two flashing codes which are onlyinitiated if the two pressure switch terminalsare open. As used in this unit, there is ajumper across the pressure switch terminals.Therefore the field should never experience aDC lockout mode unless that jumper isremoved or broken.HEATING OPERATION ERRORSTEMPERATURE LIMITIf the UCB senses zero volts from the high temperaturelimit, the indoor blower motor is immediately energized.This limit is monitored regardless of unit operation sta-tus, i.e. the limit is monitored at all times.If the temperature limit opens three times within onehour, it will lock-on the indoor blower motor and a flashcode is initiated (See Table 21).SAFETY CONTROLSThe unit control board monitors the temperature limitswitch of electric heat units.The control circuit includes the following safety controls:1. Temperature Limit Switch (TLS 1, 2).This control is located inside the heater compart-ment and is set to open at the temperature indi-cated in the Limit Control Setting Table 19. It resetsautomatically. The limit switch operates when ahigh temperature condition, caused by inadequatesupply air flow occurs, thus shutting down theheater and energizing the blower.2. Temperature Limit Switch (TLS 3, 4, 5 and 6).This control is located inside the heater compart-ment and is set to open at the temperature indicatedin the Limit Control Setting Table 19. It is a manualreset limit. These limit switches will de-energize theheaters should the primary limit fail to open or thecontactors fail to open in a failure mode.