Improper Cooling Air Flow - Bryant 355MAV Troubleshooting Manual

IMPROPER COOLING AIR FLOW - Generally, this indicates the Y/Y2 thermostat lead is not
properly connected. If User Interface is connected to ABCD connector then the wrong size
outdoor unit could be configured in the User Interface.
STEP
1. Remove blower access panel and depress door switch. Use a piece of tape to hold switch
closed.
2. Set thermostat to call for cooling. If thermostat does not have G connection jumper across
thermostat terminals R and G.
3. Make sure thermostat fan control is in the AUTO position if equipped.
4. Do you have 24-vac across Y/Y2 and C
5. You have a defective thermostat, or a break in the wiring between the thermostat and the
furnace, or the Y/Y2 thermostat terminal is not wired to the thermostat.
6. Fix the problem.
7. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.
8. Are the air conditioning airflow select switches A/C set to the proper airflow as required by the
condensing unit? Typical airflow is based on 350 CFM/TON (See Table 2.)
9. Set the air conditioning airflow select switches A/C to the proper airflow as required by the
condensing unit. (See Table 2.)
10. Disconnect the G thermostat lead or jumper if used.
11. Does the blower motor turn off in 5 seconds when the G thermostat lead is disconnected?
Note: When using a Thermidistat the blower may change airflow when the G thermostat lead
is disconnected and a call to dehumidify is active.
12. Replace the variable speed furnace control.
13. Reconnect the G thermostat lead or jumper and observe operation of furnace in cooling mode
for 10 minutes.
14. Does the furnace operate properly in cooling mode?
15. - Check outdoor unit for correct suction pressure and verify charge.
- Check filter(s) and ductwork for restrictions.
- Check furnace coil.
16. Does the AMBER LED abruptly shut off as the blower comes up to speed?
17. Do you have less than 17 vac between R and C
18. Do you have less than 90 vac between L1 and NEUTRAL-L2 on the variable speed furnace
control?
19. Make sure the wire gage between main fuse box and furnace complies with wire size
specification in Installation, Start-Up, and Operating Instructions.
20. Disconnect the R thermostat lead.
21. Do you have less than 17 vac between R and C
22. Replace transformer.
23. Check the thermostat wire gage between furnace and thermostat, and furnace and outdoor unit.
It is recommended that AWG No. 18 color-coded copper thermostat wire be used for lengths
up to 100 ft. For wire lengths over 100 ft, use AWG No. 16 wire.
24. Is Status Code 41 flashing?
25. Go to the page number indicated in the Index for Status Code 41.
26. - Check outdoor unit for correct suction pressure and verify charge.
- Check furnace coil.
27. Is a User Interface connected to the ABCD connector?
28. The wrong size outdoor unit may have been selected in the User Interface. You will need to
set the proper size of the outdoor unit in the User Interface. If set properly then the User
Interface may be reducing the airflow for dehumidification.
ACTION
-24V on the variable speed furnace control?
OM
-24V on the variable speed furnace control?
OM
-24V on the variable speed furnace control?
OM
- 11 -
YES NO GO TO
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INDEX
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INDEX
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