No Heat? Check These Things First
If your furnace or heat pump is not heating your home, there are a few safe
things you can check before calling for service.
Before you start:
These checks are intended for homeowners and do not require opening the furnace,
working around exposed wiring, handling refrigerant, or working on gas components.
If anything looks unsafe, smells unusual, repeatedly trips a breaker, or you are
uncomfortable with a check, stop and call for service.
Simple No Heat Troubleshooting
1
Check the Thermostat
Start with the simple stuff.
- Make sure the thermostat is set to HEAT.
- Set the temperature several degrees above the current room temperature.
- If the thermostat uses batteries, replace them if they are weak or dead.
- Make sure the thermostat display is on and responding normally.
2
Check the Circuit Breaker
Your furnace, air handler, or heat pump requires electrical power even if you
have gas heat.
- Look for a breaker labeled Furnace, HVAC, Air Handler, or Heat Pump.
- If the breaker is tripped, reset it one time.
- If it trips again, leave it off and call for service.
3
Check the Furnace Power Switch
Many furnaces have a regular wall-style switch nearby that controls power to
the furnace.
- Make sure the switch is in the ON position.
- It can sometimes be accidentally turned off while cleaning or moving items.
4
Check the Air Filter
A severely restricted filter can reduce airflow and may cause some heating
systems to shut down on a safety limit.
- Inspect the filter.
- Replace it if it is heavily loaded with dust or debris.
- Make sure the replacement filter is installed in the correct direction.
5
Check Supply and Return Vents
Your system needs airflow through the house to operate correctly.
- Make sure major supply registers are open.
- Do not block return-air grilles with furniture, rugs, boxes, or other items.
- Check whether any air is coming from the vents when the thermostat calls for heat.
6
If You Have a Gas Furnace
Without taking anything apart, check whether the gas supply appears to be
available.
- Make sure the home's gas service has not been interrupted.
- If there is an accessible furnace gas shutoff valve, make sure it has not been accidentally closed.
- Do not remove furnace panels or attempt to light burners manually.
7
If You Have a Heat Pump
Look at the outdoor unit from a safe distance while the thermostat is calling
for heat.
- See whether the outdoor unit is running.
- A light coating of frost during cold weather can be normal.
- A unit completely covered in heavy ice is not normal.
- Do not chip ice from the coil or pour hot water over the equipment.
8
Try One Thermostat Reset
If everything appears normal but the system still is not responding, you can
try one simple reset.
- Set the thermostat to OFF.
- Wait about 5 minutes.
- Set it back to HEAT.
- Raise the temperature several degrees above room temperature.
If it still does not heat, repeated resets usually will not solve the problem.
Stop and Call for Service If:
- You smell natural gas or propane.
- You smell burning plastic or electrical insulation.
- A breaker trips repeatedly.
- The furnace starts and shuts down over and over.
- The blower runs but the air never gets warm.
- Your heat pump is heavily iced over.
- You hear unusual buzzing, grinding, banging, or electrical sounds.
- The equipment requires opening panels or electrical testing.
Still No Heat?
At that point, the problem needs to be diagnosed instead of guessed at.
Grease & Threads Mechanical and HVAC services heating systems throughout
Sullivan County and the surrounding west-central Indiana area.
We focus on finding what actually failed and repairing the existing equipment
whenever repair makes sense. We do not automatically turn a service call into
a sales pitch for a new system.
Call or Text 812-564-3719
Why Start With a Diagnosis?
A no-heat condition can be caused by something simple such as a thermostat,
switch, dirty filter, or failed control component. It can also involve an
ignition problem, blower problem, electrical failure, safety control, heat pump
problem, or other equipment fault.
The right repair starts by testing the equipment and finding the actual cause.
That is how we approach our service calls.
