Carrier Infinity 96 not heating

humblerumble

We had a Carrier installed in '04. It's been maintained yearly etc. Last year just prior to christmas the cicuit board was replaced and furnace checked over and we were told the furance was in excellant shape.(maintained well) Yesterday, I wanted the house warmer and increased the heat on the programmable thermastat by 5 degrees. However the furance wouldn't heat the house any warmer then 68. I changed the filter, changed the batteries in the thermastat and no increase in heat. Although the furance seems to be working the temp in the home is decreasing. Any suggestions to what the problem could be?
Thank you

hvactech126

if you have returns in an unconditioned space, then check to make sure there are no leaks or loose ducting. It could be that there is a gas supply problem from the gas utility (low pressure). Have you verified the burners are operating?

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yuri

If it is a 2 stage furnace then it may be not going to high fire for a variety of reasons and you need to call a Carrier tech.

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Houston204

If you have the Carrier Infinity stat you can see the the heating stage from your stat.

beenthere

How cold was it outside.

old_squid

It's possible for some reason the furnace is not going into high fire mode.

Has anyone ever shown you how to check the status of the furnace via the LED lights? How to understand these lights is explained on the inside of the door of the furnace.

By watching these lights you can tell if the furnace is in low or high fire or if there is a fault with the furnace. By turning up the thermostat 5° you "should" force it into high fire.

HVAC1000

what makes you think the furnace is running fine? is it just because you hear the fan start or do you actually feel the warm air come out of vents or have you actually looked in the furnace cabinet and seen it firing off?

humblerumble

I assumed the furance was running fine as were getting heat just not what the set temp of the thermastat was. We called and had a tech was here who said the furance was working fine, he installed a new thermastat and left.
So I will do as mentioned and see what happens when the furance fires up..as it is now dropping in temp 2 degree a day.
Tech told us it was a faulty thermastat that was causing the problems.( miscommunicating between the furance and thermastat)