Carrier 58MSA instruction manual → Troubleshooting Guide

→Troubleshooting Guide

START

Is red LED status light on?

YES

NO

Is there 115v at L1 and L2?		NO
	YES
		NO
Is there 24v at SEC-1 and SEC-2?
	YES
Replace control center.

Is door switch closed?		NO
	YES
		NO
Is there 115v going to switch?

YES

Replace door switch.

Replace transformer.

Close door switch and go to start.

Is circuit breaker closed?			NO
	YES
		Close circuit breaker and
		go back to start.

14

Is red LED status light blinking rapidly without a pause?

NO

Is red LED status light blinking ON/OFF slowly with a combination of short and long flashes?

YES

Determine status code. The status code is a 2 digit number with the first digit determined by the number of short flashes and the second digit by the number of long flashes.

YES

NO

Check for correct line voltage polarity. If units are twinned, check for proper low-voltage (24v) transformer phasing.

Check for previous fault by momentarily shorting the TEST terminal and the C terminal until the LED goes out. LED will flash the status code of any previous fault or the code No. 11 (1 short and 1 long flash) if no previous fault. After the control repeats the code 3 times, the control will go through a brief component test sequence. The inducer will start and run for the entire component test. The HSI, blower motor heat speed, and blower motor cool speed will run for 10-15 sec each.

Was there a previous fault code other than No. 11?

NO

Does control respond to W, Y,	NO
or G 24-vac thermostat signals?

Check for continuity in wire from circuit breaker to furnace.

Check room thermostat or interconnecting cable.

NO

Is 24 vac present at W, Y, or G terminals on the control?

YES

Go to section with status code determined.

YES

Run system through a heating or

cooling cycle to check operation.

Status codes are erased after 48

hrs or whenever power (115v

or 24v) is interrupted.

YES

Replace control if it does not respond to 24-vac signal at W, Y, or G screw terminals.