Carrier 58MCA 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?

YES

Is there 115v going to switch?

YES

Replace door switch.

Replace transformer.

NO

NO

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		YES	Check for correct line voltage
rapidly without a pause?			polarity. If units are twinned,
			check for proper low-voltage
	NO
			(24v) transformer phasing.
Is red LED status light blinking			Check for previous fault by
ON/OFF slowly with a		NO	momentarily shorting the TEST
combination of short and long			terminal and the C terminal until
flashes?			the LED goes out. LED will flash
			the status code of any previous
	YES
			fault or the code No. 11 (1 short
			and 1 long flash) if no previous
Determine status code. The
			fault. After the control repeats the
status code is a 2 digit number
			code 3 times, the control will go
with the first digit determined by
			through a brief component test
the number of short flashes and
			sequence. The inducer will start
the second digit by the number of
			and run for the entire component
long flashes.
			test. The HSI, blower motor heat
Once status code is determined,
			speed, and blower motor cool
the control will go through a brief
			speed will run for 10-15 sec each.
component test sequence. The
inducer will start and run for the
entire component test. The HSI,					NO
blower motor heat speed, and			Was there a previous fault code
blower motor cool speed will run			other than No. 11?
for 10-15 sec each.
				YES
Go to section with status code
determined.

Does control respond to W, Y, or G 24-vac thermostat signals?

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.

NO

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

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