Carrier SINGLE PACKAGE ROOFTOP UNITS ELECTRIC COOLING/GAS HEATING 48HJ015-025 User Manual

Also see for 48EJ: Installation, Start-Up and Service Instructions Installation and service instructions

Contents

5. Set the outdoor-air thermostat (OAT), located in the econo-mizer section of the unit to 75 F.6. If the outdoor temperature is below 75 F, the econo-mizer will control the mixed air with the mixed-air sen-sor. If the outdoor air is above 75 F, place a jumper aroundthe contacts of the OAT.7. Jumper terminal T to terminal T1 on the module (seeFig. 18). The economizer will go to the full open position.The outdoor-air damper will go to the full open posi-tion, and the return-air damper will go to the full closedposition.8. Adjust mechanical linkage, if necessary, for correct po-sitioning. If may be necessary to remove the filters toadjust the linkage.9. Remove the jumper from around the contacts of the OATif installed in Step 6. Remove the jumper from termi-nals T and T1 installed in Step 7.10. If the Cooling mode was simulated to operate the unitin Step 4, remove the jumper and reconnect the ther-mostat wires to terminals Y1 and Y2.Table 8 — Economizer Checkout ProceduresTEST PROCEDURE RESULTSA. Disconnect power at TR andTR1. Disconnect jumper be-tween P and P1. See Fig. 18.B. Jumper TR to 1.C. Jumper T1 to T.D. Disconnect outdoor-air ther-mostat connections from S Oand +. Factory-installed800 ohm resistor should re-main connected to S R and +.E. Reconnect power to terminalsTR and TR1. 1. LED (light-emitting diode)should be off.2. Motor is in closed position.TEST PROCEDURE RESULTSDisconnect factory-installed re-sistor from terminals S Rand +. 1. LED (light-emitting diode)should be on.2. Motor drives toward open.Table 9 — High and Low Outdoor-Air TemperatureTEST PROCEDURE RESULTSA. Reconnect factory-installed800 ohm resistor between ter-minals S R and +.B. Connect 1200 ohm checkoutresistor between terminals S Oand +.C. Turn set point potentiometerto position A. Low outdoor-air temperaturetest results:1. LED (light-emitting diode)should be on.2. Motor drives toward open.D. Turn set point potentiometerto position D.E. Disconnect 1200 ohm check-out resistor. High outdoor-air temperaturetest results:1. LED should be off.2. Motor drives toward closed.Power Failure — Dampers have a spring return. In eventof power failure, dampers will return to fully closed positionuntil power is restored. Do not manually operate dampermotor.Refrigerant Charge — Amount of refrigerant chargeis listed on unit nameplate and in Table 1. Refer to CarrierGTAC II; Module 5; Charging, Recovery, Recycling, and Rec-lamation section for charging methods and procedures.Unit panels must be in place when unit is operating dur-ing charging procedure.NO CHARGE — Use standard evacuating techniques. Afterevacuating system, weigh in the specified amount ofrefrigerant (refer to Table 1).LOW CHARGE COOLING — Using appropriate coolingcharging chart (see Fig. 33-35), add refrigerant until condi-tions of the chart are met. Note that charging charts are dif-ferent from those normally used. Charts are based on charg-ing units to correct superheat for various operating conditions.An accurate pressure gage and temperature sensing deviceare required. Connect temperature sensing device to serviceport on suction line and insulate it so that outdoor ambienttemperature does not affect reading. Indoor-air cfm must bewithin normal operating range of unit.TO USE COOLING CHARGING CHART — Take outdoorambient temperature and read the suction pressure gage. Re-fer to appropriate chart to determine correct suction tem-perature. If suction temperature is high, add refrigerant. Ifsuction temperature is low, carefully reclaim some of the charge.Recheck suction pressure as charge is adjusted.Pilot Light — If pilots do not light as described in GasHeat section on page 17, be sure that pilot orifice is not ob-structed, then check for spark ignitor malfunctions as fol-lows:1. Shut off control supply power to ignitor control pack (ICP).2. Check that spark gap is 1⁄ 8 in. 6 1 ⁄32 inch.3. Check that ICP is securely grounded.4. Check that high-voltage lead is securely connected be-tween ICP and electrode body.5. Restore power to ICP. Check that 24 v is suppliedto terminal TH of ICP.6. Check unit label diagram for correct terminal usage if anywires are removed.Fig. 33 — Cooling Charging Chart, 48HJ01521