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View Full Version : My blower fan/furnace motor on my natural gas/air conditioning system short cycles?


Udog01
Sep 23, 2010, 04:42 AM
This summer I had my air conditioning unit replaced after the previous one unknowingly froze up and as a result blew up.

The new unit was working well after it was installed in conjunction with the natural gas furnace without issue - albeit the blower on the furnace unit distributes the cold air throughout the house - although reaching the top floor is not the greatest - however when going on holidays for 2 weeks I turned up the air conditioning to 82 while we left for vacation and changed the fan from the on position to auto.

When we came back I rest the temp back down to 73 and changed the fan back to the run or on position.

Since then the fan comes on with the air but shuts itself down or off and then the a frame freezes up much like the old unit would do before it broke down.

So off goes the air as I am not looking to blow it up again.. . And with the thermostat on the heat cycle (natural gas) and the furnace in the run position or on position the fan comes on but there is a banging noise in the ducts but when I enter the basement where the furnace is you do not hear the banging - after 5 - 7 minutes the furnace motor and blower shuts down and off onlt recycle itself on again 10 minutes later and over and over we the cycle continues.

Visual inspection in the furnace - appears normal - changed the filter - previous one was okay only 1 month old to - but I still changed it. Remember ?I do not hear the noise when the blower is on and the compartment is open - but clearly this will cycle off in 5 - 7 minutes.

Thanks

Stumped.

elephantears
Oct 18, 2010, 12:10 PM
If you have a thermostat that can control the fan, it needs to be configured properly. If you have a hybrid heat pump split system, the thermostat will control the fan at different speeds for heat pump heat and low fan speed for gas heat.
If the outside unit has a reversing valve, it is a heat pump. Combined with a furnace inside, a hybrid heat pump is the best of both worlds.www.greenheatandac.com