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IMPROPER COOLING AIR FLOW - Generally, this indicates the Y/Y2 thermostat lead is not
properly connected.
If a Communicating Wall Control is connected to communication
connector PL7 then the wrong size outdoor unit could be configured in the Communicating
Wall Control.
STEP
ACTION
YES
NO
GO TO
1.
Remove blower door and depress door switch. Use a piece of tape to hold switch closed.
27
2.
Set thermostat to call for cooling. If thermostat does not have G connection jumper across
thermostat terminals R and G.
3
3.
Make sure thermostat fan control is in the AUTO position if equipped.
4
4.
Do you have 24-vac across Y/Y2 and C
OM
-24V on the modulating furnace control?
8
5
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
6.
Fix the problem.
7
7.
Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.
INDEX
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.)
10
9
9.
Set the air conditioning airflow select switches A/C to the proper airflow as required by the
condensing unit. (See Table 2.)
7
10.
Disconnect the G thermostat lead or jumper if used.
11
11.
Does the blower motor turn off in 5 seconds when the G thermostat lead is disconnected?
Note:
When using a humidity sensing thermostat the blower may change airflow when the G
thermostat lead is disconnected and a call to dehumidify is active.
12
13
12.
Replace the modulating furnace control.
7
13.
Reconnect the G thermostat lead or jumper and observe operation of furnace in cooling mode
for 10 minutes.
14
14.
Does the furnace operate properly in cooling mode?
15
16
15.
- Check outdoor unit for correct suction pressure and verify charge.
- Check filter(s) and ductwork for restrictions.
- Check furnace coil.
INDEX
16.
Does the AMBER LED abruptly shut off as the blower comes up to speed?
17
24
17.
Do you have less than 17-vac between R and C
OM
-24V on the modulating furnace control?
18
24
18.
Do you have less than 90-vac between L1 and L2 on the modulating furnace control?
19
20
19.
Make sure the wire gage between main fuse box and furnace complies with wire size
specification in Installation, Start-Up, and Operating Instructions.
6
20.
Disconnect the R thermostat lead.
21
21.
Do you have less than 17-vac between R and C
OM
-24V on the modulating furnace control?
22
23
22.
Replace transformer.
7
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.
6
24.
Is Status Code 4 + 1 flashing?
25
26
25.
Go to the page number indicated in the Index for Status Code 4 + 1.
INDEX
26.
- Check outdoor unit for correct suction pressure and verify charge.
- Check furnace coil.
7
27.
Is a Communicating Wall Control connected to communication connector PL7?
28
2
28.
The wrong size outdoor unit may have been selected in the Communicating Wall Control.
You will need to set the proper size of the outdoor unit in the Communicating Wall Control.
If set properly then the Communicating Wall Control may be reducing the airflow for
dehumidification.
7
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