Carrier 58TMA operating instructions SpeedSelection, AmpDraw Check With Ammeter

Table 12—Speed Selection

COLOR	SPEED	AS SHIPPED
White	Common	COM
Black	High	Cool
Yellow	Med-High	SPARE
Orange†	Med	SPARE or Capped
Blue	Med-Low	High-Gas-Heat
Red	Low*	Low-Gas-Heat

* Continuous fan speed.

† Available on 5-speed blowers only.

Recheck temperature rise. It must be within limits specified on unit rating plate. Recommended operation is at midpoint of rise range or above.

THERMOSTAT SUBBASE TERMINALS WITH THERMOSTAT REMOVED (ANITICIPATOR, CLOCK, ETC.,

MUST BE OUT OF CIRCUIT.)

HOOK-AROUND AMMETER

R Y W G

10 TURNS

FROM UNIT 24-V

CONTROL TERMINALS

EXAMPLE:	5.0 AMPS ON AMMETER	=	0.5 AMPS FOR THERMOSTAT
	10 TURNS AROUND JAWS		ANTICIPATOR SETTING

A96316

Fig. 21—Amp Draw Check With Ammeter

components in R-W/W1 circuit. Accurate amp draw read- ings can be obtained at wires normally connected to thermostat subbase terminals R and W/W1. Fig. 21 illus- trates an easy method of obtaining actual amp draw. The amp reading should be taken after blower motor has started and furnace is operating in low heat. To operate furnace in low heat, first move SW-2 to ON position, THEN connect ammeter wires as shown in Fig. 21. The thermostat anticipator should NOT be in this circuit while measuring current. If thermostat has no subbase, thermostat MUST be disconnected from R and W/W1 wires during current measurement. Return SW-2 to final desired location after completing reading. See thermostat manufacturer’s instruc- tions for adjusting heat anticipator and for varying heating cycle length.

b.When using an electronic thermostat, set cycle rate for 3 cycles per hr.

CHECK SAFETY CONTROLS

The flame sensor, gas valve, and pressure switches were all checked 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 gradually block off return air after furnace has been operating for a period of at least 5 minutes. As soon as limit has shut off burners, return-air opening should be unblocked. By using this method to check limit control, it can be established that the limit is functioning properly and will operate if there is a motor failure.

2.Check draft safeguard switch.

The purpose of this control is to permit safe shutdown of he furnace during certain blocked vent conditions.

a.Disconnect power to furnace and remove vent connector from furnace flue collar. Be sure to allow time for vent connector pipe to cool down before removing.

b.Restore power to furnace and set room thermostat above room temperature.

c.After normal start-up, allow furnace to operate for 2 minutes, then block flue outlet 100 percent. Furnace should cycle off within 2 minutes.

d.Remove blockage and reconnect vent connector to furnace flue 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 motor lead wires from wire harness.

c.Turn on 115-v power to furnace

d.Close thermostat switch as if making normal furnace start. If hot surface ignitor does not glow within several minutes and 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.

a.Turn off 115-v power to furnace.

b.Remove blower access door.

c.Disconnect red motor lead at blower speed selector. Mark terminal for proper reconnection.

d.Replace blower access door.

e.Turn on 115-v power to furnace. Be sure room thermostat is calling for low heat.

f.Allow furnace to operate until auxiliary limit activates, but DO NOT operate furnace longer than 4 minutes.

g.If furnace operates for 4 minutes, check/replace limit switch(es).

h.Turn off 115-v power to furnace.

i.Remove blower access door.

j.Reconnect red motor lead, reset switch, and replace door.

k.Turn on 115-v power to furnace.

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