Carrier 59MN7A Troubleshooting Guide download pdf (Page 17)

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Status Code 14

IGNITION LOCKOUT - This status code indicates the furnace failed to ignite gas and/or prove flame in 4 attempts. The

modulating furnace control will auto-reset in 3 hours. If the inducer motor is not running during lockout refer to status code

34.

If the inducer motor is running at full speed during lockout this indicates that flame sense was lost 3 times within 60 minutes of

cumulative gas valve operating time after the gas valve was already ON for 70 seconds. It is usually caused by flame rollout

that causes loss of flame sense before the flame rollout switch can trip.

Status Code 15

BLOWER MOTOR LOCKOUT - This status code indicates the blower failed to reach 250 RPM or the blower failed to

communicate to the modulating furnace control within 30 seconds after being turned ON in two successive heating cycles.

Control will auto reset after 3 hours. Refer to status code 41.

Status Code 21

GAS HEATING LOCKOUT - This status code indicates the gas valve relay GVR on the modulating furnace control is stuck

closed or there is a miswire/short to gas valve BLUE wire. The modulating furnace control will NOT auto-reset.

STEP ACTION YES NO GO TO

1. Remove blower door. Disconnect User Interface ABCD connector (if used) or the R

thermostat lead (if used) from the furnace control board. Depress door switch.

2. Does status code 21 flash? 3 6

3. There is a miswire or short to the gas valve BLUE wire. 4

4. Fix problem 5

5. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. INDEX

6. Does a different status code flash? 7 8

7. Go to page number indicated in the Index for the section covering the status code. INDEX

8. Use a piece of tape to hold door switch closed. 9

9. Jumper R and W/W1 thermostat terminals. 10

10. Does status code 21 start flashing when the low pressure switch LPS makes? 11 12

11. Replace the modulating furnace control. 5

12. Does a different status code flash? 7 13

13. Disconnect the jumper wire across R and W/W1 thermostat terminals and wait until the blower

stops.

14. Cycle the furnace several times to check for intermittent operation. 15

15. Does status code 21 ever flash? 11 16

16. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. If

the problem persists on an intermittent basis, replace the modulating furnace control. If

problem still persists on an intermittent basis after replacing the modulating furnace control,

contact your distributor.

INDEX

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 47 48

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Carrier 59MN7A Troubleshooting Guide Page 17