DIYbanter - View Single Post - Forced Air Furnace not reaching thermostat setting

Zyp

wrote:
My Amama 115,000 btu forced air system (1987) with White-Rodgers
controller is not reaching its thermostat setting. My thermostat is a
Honeywell set-back model. The furnace has a particular problem in the
morning to raise the temperature from the low temperature that is used
at night.

1. Thermostat calls for heat.
2. Induced Draft motor starts
3. Furnace makes a clicking noise and ignitor turns on
4. Blower turns on.
5. High temperature limit turns off burners (after 4 minutes)
6. Ignitor turns on
7. Gas lights and stays on for about (4 minutes)
8. Furnace turns off without reaching thermostat setting

I can shut the power off to reset the furnace and it will light off
again for about 15 minutes again. I have changed the Flame senor to
be sure that it is not causing the problem.

Is there anything anyone has to offer on what might be tripping the
furnace?

Shep;

Sounds like a dirty air filter or the cooling coil is blocked from a build
up of material [dirt.] A high limit control trip is a clear sign that
there's an airflow problem. Make sure the filter is clean, all the supply
registers are open and you can "feel" air flow when the unit runs the fan.
If not, look at the duct or the evaporator coil for a blockage.

--
Zyp