Blower runs on "ON", but not on "Auto"

seminole · #1 Jan 17, 2007, 09:12 AM

Hello All,
I have a Goodman COMBINATION HEATING AND COOLING OUTDOOR UNITS PG/PGX SERIES (100K BTU). It failed to warm the space. The fan would not run on “ON” or “Auto” mode. Upon investigating, there is no power to the unit due to 25 amps fuses blown. Replaced with new fuses. Power was supplied to the unit, fan can turn on manually (“ON” mode).
When the thermostat was in Heat and Auto mode, the temperature set at 80F. The furnace ignited, felt a breeze of warm air for 3-4 minutes, but the blower was not kicked in to deliver the heat. After 3-4 minutes, the furnace shut down. Reset the thermostat (heat OFF), set Heat and Auto. This time, it was NO HEAT and NO FAN

According to manual:
SEQUENCE OF OPERATION
1. Thermostat calls for heat.
2. Combustion motor is energized, combustion motor interlock is made.
3. Ignition spark is energized.
4. Pilot valve opens and pilot burner lights
5. Sensor proves pilot flame.
6. Ignition spark de-energized.
7. The main gas valve is energized.
8. Pilot flame lights the main burners.
9. Thermostat is satisfied and opens. The main and pilot valves are de-energized, shutting down main and pilot flames.

Here is the wiring instruction:
LEAD -> THERMOSTAT
White -> W (Heat)
Green -> G (Fan)
Yellow -> Y (Cool)
Red R -> (24V.)
Orange -> Y1 Only when economizer is utilized
Pink -> Y2" (not available)

Can anyone please help to troubleshoot this problem? Any inputs are greatly appreciated.
Thanks, Seminole

NorthernHeat · Jan 17, 2007, 04:02 PM

Sounds like the circuit board is bad, since the fan relay on the board has failed, the blower never turns on, the furnace overheats and the main limit turns everything off when it realizes the furnace is overheated.

seminole · Jan 18, 2007, 07:00 AM

Quote:

Originally Posted by seminole

Hello All,
I have a Goodman COMBINATION HEATING AND COOLING OUTDOOR UNITS PG/PGX SERIES (100K BTU). It failed to warm the space. The fan would not run on “ON” or “Auto” mode. Upon investigating, there is no power to the unit due to 25 amps fuses blown. Replaced with new fuses. Power was supplied to the unit, fan can turn on manually (“ON” mode).
When the thermostat was in Heat and Auto mode, the temperature set at 80F. The furnace ignited, felt a breeze of warm air for 3-4 minutes, but the blower was not kicked in to deliver the heat. After 3-4 minutes, the furnace shut down. Reset the thermostat (heat OFF), set Heat and Auto. This time, it was NO HEAT and NO FAN

According to manual:
SEQUENCE OF OPERATION
1. Thermostat calls for heat.
2. Combustion motor is energized, combustion motor interlock is made.
3. Ignition spark is energized.
4. Pilot valve opens and pilot burner lights
5. Sensor proves pilot flame.
6. Ignition spark de-energized.
7. The main gas valve is energized.
8. Pilot flame lights the main burners.
9. Thermostat is satisfied and opens. The main and pilot valves are de-energized, shutting down main and pilot flames.

Here is the wiring instruction:
LEAD -> THERMOSTAT
White -> W (Heat)
Green -> G (Fan)
Yellow -> Y (Cool)
Red R -> (24V.)
Orange -> Y1 Only when economizer is utilized
Pink -> Y2" (not available)

Can anyone please help to troubleshoot this problem? Any inputs are greatly appreciated.
Thanks, Seminole

Many thanks to NorthernHeat and Labman. How can I verify the relay is bad? Where do I find a replacement board?
Thanks, Seminole.

NorthernHeat · Jan 18, 2007, 02:31 PM

When blower is supposed to turn on you don't get 120 volts to the appropriate female stab pin on the board. Good luck finding a board on your own, wholesalers only sell to licensed contractors.



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