Carrier 58DXT Operating Instructions Manual

Also see for 58DXT: User's information manual Service and maintenance instructions

Contents

Carrier 58DXT Operating Instructions Manual Manual pdf 21 page image

Disconnect electrical power before changing speed tap (orremoving cap on 5-speed motors). A failure to follow thiswarning can cause personal injury or death.NOTE: For furnaces with 5-speed motors, ensure that unusedspeed tap is either capped or placed on SPARE terminal on controlcenter before power is restored.d. To change motor speed selection for high heat, removeblower motor lead from control HIGH-GAS-HEAT termi-nal. (See Fig. 10 and Fig. 14.) Select desired blower motorspeed lead from 1 of the other terminals and relocate it toHIGH-GAS-HEAT terminal. See Table 11 for lead coloridentification. Reconnect original lead to PARK terminal(or cover with insulating cap, if used in furnaces using5-speed blower motors). Follow this same procedure forproper selection of cool and low-gas-heat speed selection.6. Set thermostat heat anticipator.a. When using a non-electronic thermostat, the thermostatheat anticipation must be set to match amp draw ofelectrical components in R-W/W1 circuit. Accurate ampdraw readings can be obtained at wires normally connectedto thermostat subbase terminals R and W/W1. Fig. 17illustrates an easy method of obtaining actual amp draw.The amp reading should be taken after blower motor hasstarted and furnace is operating in low heat. To operatefurnace in low heat, first move SW-2 to ON position,THEN connect ammeter wires as shown in Fig. 17. Thethermostat anticipator should NOT be in this circuit whilemeasuring current. If thermostat has no subbase, thermostatMUST be disconnected from R and W/W1 wires duringcurrent measurement. Return SW-2 to final desired locationafter completing reading. See thermostat manufacturer’sinstructions for adjusting heat anticipator and for varyingheating cycle length.b. When using an electronic thermostat, set cycle rate for 3cycles per hr.CHECK SAFETY CONTROLSThe flame sensor, gas valve, and pressure switches were allchecked in the Start-Up section as part of normal operation.1. Check primary limit control.This control shuts off combustion control system and ener-gizes circulating-air blower motor if furnace overheats.The preferred method of checking limit control is to graduallyblock off return air after furnace has been operating for aperiod of at least 5 minutes. As soon as limit has shut offburners, return-air opening should be unblocked. By using thismethod to check limit control, it can be established that thelimit is functioning properly and will operate if there is amotor failure.2. Check draft safeguard switch.The purpose of this control is to permit safe shutdown of hefurnace during certain blocked vent conditions.a. Disconnect power to furnace and remove vent connectorfrom furnace flue collar. Be sure to allow time for ventconnector pipe to cool down before removing.b. Restore power to furnace and set room thermostat aboveroom temperature.c. After normal start-up, allow furnace to operate for 2minutes, then block flue outlet 100 percent. Furnace shouldcycle off within 2 minutes.d. Remove blockage and reconnect vent connector to furnaceflue collar.e. Wait 5 minutes and then reset draft safeguard switch.3. Check flow-sensing pressure switches.This control proves operation of draft inducer blower.a. Turn off 115-v power to furnace.b. Remove gas control door and disconnect inducer motorlead wires from wire harness.c. Turn on 115-v power to furnaced. Close thermostat switch as if making normal furnace start.If hot surface ignitor does not glow within several minutesand control flashes code 32, pressure switches are func-tioning properly.e. Turn off 115-v power to furnace.f. Reconnect inducer motor wires, replace gas control door,and turn on 115-v power to furnace.4. Check auxiliary limits.Table 11—Speed SelectionCOLOR SPEED AS SHIPPED‡White Common C OMBlack High CoolOrange† Med SPARE or CappedYellow Med-High SPAREBlue Med-Low High-Gas-HeatRed Low* Low-Gas-Heat* Continuous fan speed.† Available on 5-speed blowers only.‡ Terminal on control center.Recheck temperature rise. It must be within limits specifiedon unit rating plate. Recommended operation is at midpoint ofrise range or above.Fig. 17—Amp Draw Check With AmmeterA96316R Y W G10 TURNSTHERMOSTAT SUBBASETERMINALS WITHTHERMOSTAT REMOVED(ANITICIPATOR, CLOCK, ETC.,MUST BE OUT OF CIRCUIT.)HOOK-AROUNDAMMETEREXAMPLE: 5.0 AMPS ON AMMETER10 TURNS AROUND JAWS = 0.5 AMPS FOR THERMOSTATANTICIPATOR SETTINGFROM UNIT 24-VCONTROL TERMINALS21

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