Carrier GT-G Unit Operation, Diagnostic Features, CXM Control Start-up Operation, Stat signal

Carrier CXM Controls

Diagnostic Features

The LED on the CXM board advises the technician of the current status of the CXM control. The LED can display either the current CXM mode or the last fault in memory if in test mode. If there is no fault in memory, the LED will flash Code 1 (when in test mode).

CXM Control Start-up Operation

The control will not operate until all inputs and safety controls are checked for normal conditions. The compressor will have a 5 minute anti-short cycle delay at power-up. The first time after power-up that there is a call for compressor, the compressor will follow a 5 to 80 second random start delay. After the random start delay and anti-short cycle delay, the compressor relay will be energized. On all subsequent compressor calls, the random start delay is omitted.

Unit Operation

	GT-PX	GT-GS / GT-S	GT-GS / GT-S
T-stat signal
	Variable Speed	Variable Speed	PSC Air Handler
	Air Handler	Air Handler
G	Fan only	Fan only	Fan only
G, Y or Y1	Stage 1 heating1	Stage 1 heating3	Stage 1 heating5
G, Y1, Y2	Stage 2 heating1	Stage 2 heating3	Stage 2 heating5
G, Y1, Y2, W	Stage 3 heating1	Stage 3 heating3	N/A
G, W	Emergency heat	Emergency heat	Emergency heat
G, Y or Y1, O	Stage 1 cooling2	Stage 1 cooling4	Cooling6
G, Y1, Y2, O	Stage 2 cooling2	Stage 2 cooling4	N/A

1Stage 1 = 1st stage compressor, 1st stage fan operation Stage 2 = 2nd stage compressor, 2nd stage fan operation Stage 3 = 2nd stage compressor, auxiliary electric heat, 2nd or 3rd stage fan operation (depending on fan settings)

2Stage 1 = 1st stage compressor, 1st stage fan operation, reversing valve Stage 2 = 2nd stage compressor, 2nd stage fan operation, reversing valve

3Stage 1 = compressor, 1st stage fan operation Stage 2 = compressor, 2nd stage fan operation

Stage 3 = compressor, auxiliary electric heat, 2nd or 3rd stage fan operation (depending on fan settings)

4Stage 1 = compressor, 1st stage fan operation, reversing valve Stage 2 = compressor, 2nd stage fan operation, reversing valve

5Stage 1 = compressor, fan

Stage 2 = compressor, auxiliary electric heat, fan

6Cooling = compressor, fan, reversing valve

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Carrier Indoor & Outdoor Split Geothermal Heat Pumps - Rev.: 08/10/05