Carrier 52C, P manual WALL-MOUNTED Thermostat Controls, Remote Thermostat Troubleshooting

WALL-MOUNTED THERMOSTAT CONTROLS

For 52C,P wall thermostat control (RC, RP) units, all controls are located on the wall-mounted thermostat except the vent lever and outdoor thermo- stat. Remote control is a factory or field-installed option. There are 3 styles of thermostats qualified for use with 52C,P series Remote Control units. See Fig- ures 38-40. On remote control units, the fan cycle func- tion is located on the wall thermostat. The rocker switch on the control box door is used to set fan speed to high or low. Factory default is low speed.

	R	R
	G	G
TYPICAL	Y	Y
WALL
THERMOSTAT	W	W
	O	O
	C	C

TERMINAL

BLOCK

See Figures 41-43 for thermostat wiring.

A field conversion kit is available to convert an AA model (standard unit-mounted controls) to an RC model (wall-mounted controls).

IMPORTANT: No conversion kit is available to convert from an RC model back to an AA model.

TERMINAL	DESIGNATION
R	24 VAC
G	Fan
Y	Compressor
W	Electric Heat
O	Reversing Valve
C	Common

NOTES:

1.Use terminal “O” for heat pump con- nection only.

2.See table at left for terminal descriptions.

3.Common wire “C” is typically used only for digital thermostats.

4.Power stealing is NOT allowed. There must always be a hard common connec- tion between unit and digital thermostat.

FIGURE 38 — NON-PROGRAMMABLE

THERMOSTAT

FIGURE 39 — MANUAL THERMOSTAT

FIGURE 40 — PROGRAMMABLE THERMOSTAT

FIGURE 41 — WIRING CONNECTIONS

REMOTE THERMOSTAT

TROUBLESHOOTING

Thermostat display is blank:

Check to make sure there is 24 VAC to the thermostat (measure across terminals R and C at the thermostat). If there is 24 VAC at the thermostat, check connec- tions at the thermostat terminal block. If connections are good and there is 24 VAC with no display, the ther- mostat should be replaced.

Thermostat display is working but unit is not heating or cooling:

At the RC terminal block on the unit, measure the con- trol inputs coming from the thermostat. (Place one of the meter leads on C and use the other to check the voltage at each of the terminals.)

			TERMINAL
MODE		METER READINGS (VAC)
	R	G	Y	W	O (For
					HP Only)
Fan Only	24	24	0	0	0
Cooling	24	24	24	0	24
Heating
Heat Pump Unit	24	24	24	0/24*	0
Heat/Cool Unit	24	24	0	24	0

*24 VAC supplied if thermostat is in 2nd stage heating demand (large difference between room temperature and setpoint).

NOTE: For heat pump units, the Outdoor Frost Thermostat (OFT) will determine, based on outdoor temperature, whether to bring on the com- pressor or electric heat in the Heating mode.

FIGURE 42 — THERMOSTAT TROUBLESHOOTING

If the inputs are not correct, then the thermostat is not making a call for the mode requested. This could be because the thermostat is in a unit protection mode, not set up properly, miswired, has a broken wire, or it may have failed.

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