Operating a gas furnace

I inspected a home with one split system and one gas pack. It was about 90 degrees outside and the split system kept cycling on and off every few minutes. The gas pack ran with out cycling.

The home owner had the unit checked by a contractor who stated it was fine and was only cycling because it was too hot to run a gas furnace.

When my business was in Phoenix I ran many a furnace on 100 degree days and never had them cycle on a limit switch.

Do others have a limit for outside air temps when they won’t operate a gas furnace?

What did the filter look like?

What was the indoor temperature? The outdoor temperature is insignificant when running the furnace.

Not sure this helps but occasionally I run into a thermostat that will not go into heat mode above a preset.

But there is a way to bypass/change the limit.

It could most definitely cause this problem. The air from inside the house cooles the heat exchanger. If it gets to hot in there the high temperature limit switch can cycle it off. It needs cooler air to keep this from happening. Also I would check the evaporator coil. If it was dirty you might not get adequate air flow. Very dirty filter would do the same thing. Especially in a trane unit. They are very well protected. Also NEVER bypass a Safty switch in a gas system. If you do you better have enough money to pay for someone’s life. Because you could kill someone by doing so. I have seen some really dangerous situations where service technicians have done so. Another suggestion is when you have any gas appliances, buy a CO. Detector. It could be the best investment for your family you could ever buy. It just might save a life. This post is from a licensed Hvac contractor. With 25 years experience. With extensive knowledge in this area.

You did the right thing by reporting a short cycle and I bet if no repair was made it will happen again.