The equipment is in a mfg home.
The age of the equipment is new, installed 2/2008.
The Mfg is Intertherm, and uses natural gas. The furnace is inside the home, the A/C is outside.

It was 74 degrees F in the house. I set the thermostat to 79 degrees.
The fan and blower came on. Periodically, on the way to 79 degrees, the blower would shut off, the fan continued to blow for a period, then the blower comes back on. This cycle repeats until the thermostat reaches the temperature of 79 degrees.

Is this how it is supposed to work? I have never had a heater cycle on and off on the way to its desired temperature. Heaters usually blow continuously until they reaches the desired temperature and then they shut off.

Look for a red light flashing and a list of what the flashes mean, search our faq for this info

Is the mfg home new also, or just the central air system(heating and cooling) Was the thermostat replaced. If it is an older home, you may have a faulty (mercury thermostat). This would cause your short cycling. Please let me know what you find.

Exact model number? I will try to find a service manual for you.

The red light is on (steady), then when the blower shuts off and the cool down fan comes on, the red light blinks one time. I looked at the code on the inside front panel. The code means "Limit Circuit open or External Load on 'W'"
Then, after a short period, the red light is steady, and the blower comes on. This cycle repeats.
Is this how these types of furnaces are supposed to work?
The home is brand new and the furnace is brand new.

The Model is M2RC 100A-16BN
The Serial Number is M2D071103883

Quote:

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Originally Posted by hvac1000

Exact model number? I will try to find a service manual for you.

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Model M2RC 100A-16BN

If your home is new you are under warranty. I would not mess with it since any repairs done by you could be considered tampering and void the warranty.

What you are seeing is correct. More than likely there is a problem with the limit control. Dirty air filter/closed registers or other items could cause this to happen. I would call for service since your unit is under warranty.

http://www.nordyne.com/Literature/707811.pdf

http://www.nordyne.com/Literature/983a.pdf


http://www.nordyne.com/Literature/708120b.pdf

http://www.nordyne.com/Literature/708072a.pdf

http://www.nordyne.com/Literature/7103550.pdf

http://www.nordyne.com/Literature/707964.pdf

Download and keep these manuals for future reference.

Over the years the service people who will take care of your furnace might need them.