32 G6RA, G6RK Service Manual
Check-out Procedure:
1. Remove orange wires from pressure switch. Place a tee
in the hose connecting pressure switch to the inducer
housing.
2. Connect a Differential Pressure Gauge or Inclined
Manometer to tee.
3. Start induce draft motor.
4. Negative pressure created by the induced draft motor
must be greater than 0.75" W.C. for switch to close. (See
Table 7.)
5. Use an ohmmeter to check for continuity across switch.
6. If continuity is established, switch is closed. If ohmmeter
shows an infinite reading, switch is open, and must be
replaced.
If the pressure reading will not pull down to 0.75" W.C., then
there could be several reasons why:
1. Vent blockage.
2. Heat exchanger blockage.
3. Poor seal on collector box to induced draft motor.
4. Bad blower wheel in induced draft motor.
5. Crack or hole in heat exchanger.
The switch must be open to be ready for the next heating
cycle. If switch remains closed, a flash code of 3 will be
produced by the control board.
Figure 41.
Lower (Lesser) Negative Pressure Than Closing Pressure
Lower than normal negative pressure measured at the combustion blower may be caused by:
1. Restriction on outlet side of combustion blower (blocked flue, debris or venting not properly supported or sloped)
2. Leak (lack of restriction) on inlet side. Inducer inlet leaking, inducer blower wheel loose, or leak in heat exchanger.
3. To test for restriction in vent pipe to verify problem is outside of furnace, disconnect vent for test period only and start
furnace. If furnace starts, look for problem in vent pipe. Reconnect after testing.
Table 8. Lower (Lesser) Differential Negative Pressure Than Closing Pressure
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