Heil furnace cycling problem

I'm wondering if anyone has any ideas? My furnace will kick on, stay on for a minute or two and then shut off. It kicks back on again in another minute or two, stays on for a minute or two and shuts off. It cycles like this about three times. Then it comes on normally. It heats the house, but I'm told that it shouldnt operate this way. I have a Heil furnace, forced gas (pilot light), model # VG130AE R, serial # H40911916. I do not know how old it is. The furnace has done this for the two years I've owned the house. The house is a ranch on a slab foundation. Please note, I also have a central air unit (? age). Any suggestions on cause or cure? Thanks. This site is the best!

 

That name sounds dangerous so I better answer carefully.
Your furnace was made the 40th week of 1991.
Is it the fan or the burner which is cycling so quickly?

 

"That name sounds dangerous so I better answer carefully."

Nah, its like calling a bald man "Curly"!
I believe its the fan. I can hear when the burners kick on. They stay on for a minute or so and then the fan turns on. Its the fan (blowers) that cycles off and on. Someone told me it may have something to do with the thermocoupling. Does that sound right? Also, I looked at the pilot flame. It seems pretty big to me. Would that have anything to do with this cycling problem? Thanks for the quick response!

 

It would have nothing to do with the thermocouple. Judging by what you tell me, I think your furnace has a fan controled by temperature rather than time as the newer furnaces do. If this happens particularly when the thermostat is turned up several degrees such as maybe when you come home or get up & turn the heat up, it is not really unusual. The "cold" air is cooling the furnace to below the fan's cut off temperature. Once the burners have heated the metal somewhat there is enough heat in the furnace to keep the fan on until the thermostat is satisfied.

 

Thanks, Grady. I have one more thing to add though....I have been keeping the thermostat set at 64 degrees for about a month now (yes, its cold in here). I havent adjusted it at all. Does that make a difference? Also, is it ok for the furnace to run like that? Thanks again!

 

If the fan continues to cycle during the whole burn time, there is a problem. It could be as simple as an adjustment to the fan/limit switch (if your furnace has one) or setting the fan to a lower speed. On the other hand, you could have a control or fan motor going bad.
If the fan only does it a couple of times then stays on until after the burners shut off it will not hurt anything.

 

Thanks again, Grady for the advice!