Why does my Furnace exhaust cycle on and off while air conditioner is running?

The fan normally runs for a few minutes or so after the gas shuts off.

This removes the heat from the furnace and transfers it into the living space instead of just letting it possibly cause overheating of the furnace until it dissipates. If it is a fan that blows outside, that fan also needs to run for a few minutes to clear exhaust gasses from the furnace - to keep them from dissipating into your home.

Sounds like the fan limit was not replaced correctly. You can try switching the blower to the On position (instead of Auto), if the furnace runs properly with the blower on that would be the most likely culprit.

There is a diagnostic chart on the reverse side of the front panel near the wiring diagram. Usually a 3 blink indicates a pressure switch problem. Check your air filter, condensate hose and drain, intake and exhaust pipes.

Sounds like the anticipator on the thermostat is faulty.
Try replacing the thermostat.

The compressor/condenser is being called all the time. The reason it goes off is because the evaporator (indoors) freezes up when the fan is told to turn off by the thermostat. This further cooling lowers the low side pressure below the low limit switch point turning off the compressor unit.
Solution: Make sure the thermostat is wired correctly. Green wire is usually the compressor wire but maybe not.

Sounds like a problem with the circuit board.

Sounds like mine did
it was a realy switch

Furnace. To confirm use an Ampprobe or other brand ampmeter and see how much current is being drawn. If it is more that 80% of the breaker rating, it si for sure the Furnace.

problem is not the thermostat, thermostat is an on-off switch that happens to work on temperature. Your furnace is locking out. cycling the heat off switch resets the micro-processor in the furnace. You need to diagnose the problem in the furnace, to go further we will need the model and approximate age of the unit

Remove all power from the furnace, it is likely the brain in the furnace is need of being reset, from the battery replacement, why did you change the battery, was there an indicator telling you to change it?

Many times just removing all the power to the furnace will do the trick with a reset, if not let me know and we will go from there, but it sounds like the main brain is confused or bad, more likely confused, so try the power removed first.

Than let me know [email protected]