Carrier 40QA024-060 Installation, Start-up And Service Instructions Manual

Contents

18START-UPMake the following checks and complete the Start-UpChecklist on page CL-1 before system start-up. Also refer tothe condensing unit Installation, Start-Up and Service Instruc-tions for system start-up instructions and refrigerant chargingmethods.1. Check condensate drainage system:a. Remove grille and frame from the unit.b. On the opposite side of the drain connection, inserta water bottle up into the fan coil unit and fill drainpan. Refer to Fig. 22. Water must flow steadily; ifnot, check the pipe slope or inspect for any piperestrictions.2. Make sure that all wiring connections are correct andthat they are tight.3. Check that all barriers, covers, and panels are in place.Ensure that the filters and return-air grilles have beeninstalled and that the discharge louvers are positionedcorrectly.After Extended Shutdown — If the system has beenturned off for more than 12 hours and a crankcase heater is be-ing used, turn on the indoor and outdoor unit disconnectswitches to supply power to the system for 12 hours BEFOREstarting the system.Seasonal Changeovers — When changing heat pumpsystem from cooling to heating or heating to cooling, or beforestarting cooling only system after it has been out of use for thewinter season, perform the following steps BEFORE startingthe system:1. Inspect and clean the outdoor unit, particularly thecoil.2. Clean or replace the air filters in the indoor unit.3. Clean the indoor unit drain pan and drain pipe, andremove any obstructions.4. If the outdoor unit is equipped with a crankcase heater,turn on indoor and outdoor unit disconnect switches tosupply power to the system 12 hours before startingthe system.Adjusting AirflowAUTOMATIC AIR SWEEP — All units are equipped withan air sweep feature which directs the airflow louvers up anddown to provide optimum room air circulation. The air sweepfunction can be controlled by the toggle switch located on thelower right corner of the unit. If using a thermostat with an airsweep switch, see Fig. 20 and 21 for wiring modifications.Operating Mode Memory — After the system isturned off or after a power failure, the system remains in thelast operating mode selected. When the system is turned backon, or when power is automatically restored, operation contin-ues in the same operating mode as when the system shut down.Automatic Operation (Auto.) Mode — If auto.mode is selected, the system automatically switches over theoperating mode from heating to cooling, or from cooling toheating (heat pump system only) depending on the selectedtemperature. Auto. mode also controls fan speed if not manual-ly overridden.NOTE: Between the cooling cycle and the heating cycle thereis a neutral zone of approximately 2° F above and 2° F belowthe selected temperature when only the fan is operating.Operating Sequence — Ceiling-suspended fan coilunits have a relay board which controls system operation in re-sponse to a room thermostat. The user may manually select anyone of 3 fan speeds for unit operation. Ceiling-suspended sys-tems may be equipped with an accessory power ventilation kitand/or condensate pump.FAN OPERATION — Fan coils are capable of 3-speed opera-tion. See thermostat instructions for fan speed selection. Whenthe fan(s) is operating in medium or high speed and the unit isequipped with the power ventilation kit, the ventilation fan willoperate to provide fresh air.COOLING MODE OPERATION — When the room ther-mostat senses a demand for cooling, the fan coil relay board isenergized. The indoor fan(s) will start in the selected speed (ifit is not already operating). The reversing valve (heat pumponly) will energize for cooling operation.The internal condensate pump (if so equipped) runs when-ever the reversing valve is energized (heat pump only) and/orthe unit is in cooling. As long as the condensate float switchand freeze protection thermostat are closed, the cooling relaysin the fan coil unit will close. This energizes the compressorand outdoor fan in the outdoor unit. The compressor will con-tinue to operate until the room thermostat is satisfied. When thecooling demand is satisfied, the compressor and outdoor fanwill stop. If the system is in the AUTO. position, the indoor fanwill stop with the compressor. If the unit has the accessory ven-tilation kit, the ventilation fan will operate whenever the indoorfan is set for medium or high speed.HEAT PUMP OPERATION — When the room thermostatsenses a demand for heating the indoor fan will start in theselected speed (if not already operating), and the reversingvalve will not be energized. The internal condensate pump (ifsupplied) and freeze protection thermostat are not operatedduring heating operation. The control relay (CR2) closes, andthe compressor and outdoor fan are energized through the de-frost board (DFB), which is located in the outdoor unit. Themicroprocessor logic in the DFB is energized when the com-pressor starts, and the defrost timer runs. Once every 90 min-utes (factory default setting) of compressor run time, the DFBlogic checks the defrost thermostat (DFT). If the DFT is open,the unit continues in heating operation. If the DFT is closed, theDFB switches the unit to defrost mode. The timing on the DFBmay be set at either 30, 50, or 90 minutes.DEFROST (Heat Pump Only) — The DFB energizes theRVS (reversing valve solenoid), and the reversing valveswitches to the cooling position. The K1 relay on the DFBopens and the outdoor fan stops. The W2 contact on the DFB isalso energized, which in turn energizes the defrost relay on thefan coil relay board, turns off the electric heater and stops theindoor fan.The DFB logic checks the 10-minute defrost timer and theDFT. If the DFT opens in less than 10 minutes, the DFBswitches the unit back to normal heating operation. If the DFTremains closed, the DFB switches the unit back to heating op-eration after 10 minutes. When the DFB changes back to heat-ing mode, the RVR (reversing valve relay) is deenergized andthe reversing valve switches back to heating operation. Boththe outdoor and indoor fans come back on, and if necessary, theelectric heater also turns on.SYSTEM SAFETIES — The system is equipped with thefollowing safety devices to protect system components:Indoor coil freeze protection thermostat — If a coil temper-ature of 28 F or lower is sensed, the compressor and outdoorfan will be shut down until the coil temperature exceeds 28 F.The indoor fan will continue to run.Condensate float switch (units equipped with accessorycondensate pump, cooling cycle only) — If the level of con-densate in the drain pan rises too high, the condensate floatswitch will turn the system off.Never operate unit without a filter or with grille removed;damage to the unit or personal injury may result.