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Phil, Mechanical Engineer
Category: HVAC
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Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a RUUD furnace model# ***** which suddenly

Customer Question

I have a RUUD furnace model# ***** which suddenly the blower continually runs even with the thermostat fan switched to the auto setting. Flipping the breaker stops it but flipping back on returns the blower to running all of the time. Replaced
the relay today as recommended through "just answer" and the blower continues to run.
Submitted: 1 year ago.
Category: HVAC
Customer: replied 1 year ago.
Duplicate Question - Disregard
Expert:  gotoman for ac replied 1 year ago.
If you replaced fan relay you may have a stuck sequencer. On the relay remove the 24 volt wire going to the 24 volt coil on relay. See if fan shuts off. This is just checking for shorted wires. Let me know if fan stops. Russ
Customer: replied 1 year ago.
Unsure as to which wire is the 24 volt wire - Wiring diagram is attached
Expert:  gotoman for ac replied 1 year ago.
Thanks great help. Remove wire from normally closed terminal on relay. This wire is fed from heat strips when energized. Let me know if fan shuts off/ Russ
Customer: replied 1 year ago.
removing stopped the fan after power restored. nothing else works either though.
Expert:  gotoman for ac replied 1 year ago.
Fan will not run when you call for cooling.
Customer: replied 1 year ago.
Correct although house is 73 degrees cool. Should it run with the wire removed. Heat has never been turned on since moving in 2008; live in Miami.
Expert:  gotoman for ac replied 1 year ago.
Is thermostat turned below 73.
Expert:  gotoman for ac replied 1 year ago.
It should run when calling for cooling. Russ
Customer: replied 1 year ago.
Removing the wire from NC on the BR kills the blower but does not turn on when the outside unit starts for cooling.
Expert:  gotoman for ac replied 1 year ago.
Switch the wires on NC and NO to see if it works properly. Russ
Customer: replied 1 year ago.
Same result
Expert:  gotoman for ac replied 1 year ago.
Put wires back to normal positions. Remove green/black wire and see if fan stops. Russ
Expert:  gotoman for ac replied 1 year ago.
Remove while unit is not calling for cooling or cooling is in off position. Russ
Expert:  gotoman for ac replied 1 year ago.
Did that stop fan. Russ
Customer: replied 1 year ago.
Will try and advise
Expert:  gotoman for ac replied 1 year ago.
Ok
Customer: replied 1 year ago.
Removing the green and black wire stopped the fan. Calling for cool did not start the fan.
Expert:  gotoman for ac replied 1 year ago.
Good job. Ok fan relay is energizing, Check thermostat and make sure the fan is not at the on position. If it is on the auto position and fan is running when not calling for cool. You have shorted wire or bad thermostat. To check bad thermostat remove the green wire from G on thermostat and see if the fan stops. Russ
Customer: replied 1 year ago.
Pulled G from thermostat and fan did not stop. Replaced thermostat with original device and the fan did not stop. Do you think it could be the heat relay? This identical issue occurred last October and sometime in mid December, the fan went back to normal with no intervention from me. Left for vacation recently with everything running normal, came back to the fan running constantly. Only anomaly is a couple of bad storms passed through the area.
Customer: replied 1 year ago.
rewired the old mercury thermo and issue has been resolved. Thanks for your assistance.
Expert:  gotoman for ac replied 1 year ago.
You are welcome. Russ

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