Carrier Performance 25TPB7 Installation Instructions Manual

25TPB7: Installation InstructionsManufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.10Check ChargeNOTE: CHARGE IN HIGH STAGE ONLY.Factory charge amount and desired subcooling are shown on unit ratingplate. Charging method is shown on information plate inside unit. Toproperly check or adjust charge, conditions must be favorable forsubcooling charging. Favorable conditions exist when the outdoortemperature is between 70°F and 100°F (21.1°C and 37.8°C), and theindoor temperature is between 70°F and 80°F (21.1°C and 26.7°C).Follow the procedure below:Unit is factory charged for 15ft (4.6 m) of lineset. Adjust charge byadding or removing 0.6 oz/ft (.018 kg/m) of 3/8 liquid line above orbelow 15ft (4.6 m) respectively.For standard refrigerant line lengths (80 ft/24.4 m or less), allow systemto operate in cooling mode at least 15 minutes. If conditions arefavorable, check system charge by subcooling method. If any adjustmentis necessary, adjust charge slowly and allow system to operate for 15minutes to stabilize before declaring a properly charged system.If the indoor temperature is above 80°F (26.7°C), and the outdoortemperature is in the favorable range, adjust system charge by weightbased on line length and allow the indoor temperature to drop to 80°F(26.7°C) before attempting to check system charge by subcoolingmethod as described above.If the indoor temperature is below 70°F (21.1°C), or the outdoortemperature is not in the favorable range, adjust charge for line set lengthabove or below 15ft (4.6 m) only. Charge level should then beappropriate for the system to achieve rated capacity. The charge levelcould then be checked at another time when the both indoor and outdoortemperatures are in a more favorable range.NOTE: If line length is beyond 80 ft (24.4 m) or greater than 20 ft (6.1m) vertical separation, See Long Line Guideline for special chargingrequirements.Heating Check Chart ProcedureTo check system operation during heating cycle, refer to the HeatingCheck Chart on outdoor unit. This chart indicates whether a correctrelationship exists between system operating pressure and airtemperature entering indoor and outdoor units. If pressure andtemperature do not match on chart, system refrigerant charge may not becorrect. Do not use chart to adjust refrigerant charge.Verify units for proper switching between low & highstagesCheck the suction pressures at the service valves. Suction pressureshould be reduced by 3-10% when switching from low to high capacity.Compressor current should increase 20-45% when switching from lowto high stage. The compressor solenoid when energized in high stage,should measure 24vac at leads inside control box.When the compressor is operating in low stage the 24v DC compressorsolenoid coil is de-energized. When the compressor is operating in highstage, the 24v DC solenoid coil is energized. The solenoid plug harnessthat is connected to the compressor HAS an internal rectifier thatconverts the 24v AC signal to 24v DC. DO NOT INSTALL A PLUGWITHOUT AN INTERNAL RECTIFIER.Unloader Test ProcedureThe unloader is the compressor internal mechanism, controlled by theDC solenoid, that modulates between high and low stage. If it issuspected that the unloader is not working, the following methods maybe used to verify operation.1. Operate the system and measure compressor amperage. Cycle theunloader on and off at 30 second plus intervals at the thermostat(from low to high stage and back to low stage). Wait 5 secondsafter staging to high before taking a reading. The compressoramperage should go up or down at least 20 percent.2. If the expected result is not achieved, remove the solenoid plugfrom the compressor and with the unit running and the thermostatcalling for high stage, test the voltage output at the plug with a DCvoltmeter. The reading should be 24 volts DC.3. If the correct DC voltage is at the control circuit molded plug,measure the compressor unloader coil resistance. The resistanceshould be approximately 1640 milliohms. If the coil resistance isinfinite or is grounded, the compressor must be replaced.Final ChecksIMPORTANT: Before leaving job, be sure to do the following:1. Ensure that all wiring is routed away from tubing and sheet metaledges to prevent rub-through or wire pinching.2. Ensure that all wiring and tubing is secure in unit before addingpanels and covers. Securely fasten all panels and covers.3. Tighten service valve stem caps to 1/12-turn past finger tight.4. Leave Owner’s Manual with owner. Explain system operation andperiodic maintenance requirements outlined in manual.5. Fill out Dealer Installation Checklist and place in customer file.

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