HVAC Troubleshooting Guide

If your furnace isn't producing heat, start by making sure the thermostat is set to Heat and the temperature is set above the current room temperature.

Then check:

• The furnace air filter and replace it if it is dirty.

• Supply and return vents to make sure they are open and unobstructed.

• The furnace power switch to make sure it hasn't accidentally been turned off.

• Your electrical panel for a tripped furnace breaker.

• If you have a gas furnace, make sure the home's gas supply hasn't been intentionally shut off.

If your furnace still won't heat your home, avoid opening the equipment or attempting to repair gas, electrical, or ignition components yourself. Contact Sun Services for professional furnace service.

A furnace may briefly blow cooler air when it first starts or near the end of a heating cycle. If it continues blowing cool air, check:

• That your thermostat is set to Heat.

• That the thermostat fan setting is set to Auto rather than On.

• The furnace air filter for dirt or restriction.

• Supply and return vents for blockages.

If the furnace continues running without producing adequate heat, there may be an issue with the heating or control system that requires professional diagnosis.

First, make sure the thermostat is set to Heat and set above the current indoor temperature.

You can also check:

• Whether the thermostat display is working.

• Thermostat batteries, if your thermostat uses them.

• The furnace power switch.

• The furnace breaker in your electrical panel.

• The HVAC air filter.

If the furnace still doesn't start, don't remove panels, bypass safety switches, or attempt electrical or gas repairs. Call or text Sun Services at 269-684-3898 for service.

If your heat pump isn't keeping your home warm, first confirm that the thermostat is set to Heat and set above the current indoor temperature.

Then check:

• The HVAC air filter.

• Supply and return vents.

• The indoor and outdoor unit breakers.

• The outdoor unit for excessive debris or anything restricting airflow.

• Whether the thermostat is displaying an error or warning.

Keep in mind that heat pumps can sometimes deliver air that feels cooler than air from a traditional gas furnace while still heating the home.

If your home isn't reaching the thermostat setting or the heat pump isn't operating normally, Sun Services can diagnose the system.

Make sure your thermostat is set to Cool and below the current indoor temperature.

Check:

• The HVAC air filter for dirt or restriction.

• Supply and return vents for blockages.

• The heat pump breakers.

• The outdoor unit for leaves, grass, or other debris restricting airflow.

• The thermostat for error messages or unusual readings.

If the heat pump continues running without adequately cooling your home, professional diagnosis may be needed.

If your boiler isn't heating your home, first make sure the thermostat is set to Heat and above the current indoor temperature.

You can also check:

• The boiler's electrical power switch.

• The appropriate circuit breaker.

• Whether the thermostat is operating normally.

• Whether the boiler is displaying an error or fault code.

Avoid opening the boiler, adjusting internal components, or attempting gas or electrical repairs yourself.

If the boiler still isn't providing heat, contact Sun Services for professional diagnosis.

If little or no air is coming from your vents, start by checking the thermostat and make sure the system is calling for heating or cooling.

Then check:

• The HVAC air filter.

• Supply and return vents.

• The furnace or air handler power switch.

• The appropriate breaker in your electrical panel.

• The thermostat display and batteries, if applicable.

Very low airflow can also indicate an equipment or ductwork problem. If these basic checks don't restore normal airflow, schedule professional service.

If your thermostat screen is blank, check whether it uses replaceable batteries and install fresh batteries if necessary.

You can also check:

• The furnace or air handler power switch.

• Your home's HVAC circuit breaker.

• Whether other electrical equipment in the home has lost power.

Some thermostats receive power directly from the HVAC system, so a blank thermostat can sometimes indicate a problem elsewhere in the system.

If power appears normal but the thermostat remains blank, Sun Services can inspect the thermostat and HVAC controls.

Frequent starting and stopping is sometimes called short cycling. Before scheduling service, check:

• Whether the air filter is dirty or clogged.

• Whether supply and return vents are open.

• Whether the thermostat is located near a heat source, direct sunlight, or another condition that could affect its temperature reading.

• Whether the thermostat settings appear correct.

Short cycling can also be caused by equipment, electrical, control, or system-sizing issues. If it continues after these basic checks, the system should be professionally inspected.

Occasional operating sounds are normal, but new or unusually loud banging, grinding, screeching, buzzing, or rattling can indicate a problem.

Check that nothing outside the equipment is obviously loose or obstructing airflow, but do not remove equipment panels or reach inside the system.

If the noise is severe, accompanied by a burning smell, or the equipment appears unsafe, turn the system off and have it professionally inspected.

If your home isn't reaching the temperature set on your thermostat, check:

• The thermostat's heating or cooling mode.

• The HVAC air filter.

• Supply and return vents.

• Doors and windows that may have been left open.

• The outdoor HVAC unit for airflow restrictions.

• Whether the system is running normally or frequently starting and stopping.

Extremely hot or cold outdoor conditions can affect system performance, but persistent difficulty maintaining temperature can indicate an equipment or system problem.

Homeowner troubleshooting should be limited to simple checks such as thermostat settings, filters, vents, power switches, and circuit breakers.

Stop troubleshooting and seek professional assistance if you notice:

• A gas odor.

• Smoke or sparking.

• Burning or strong electrical odors.

• Repeatedly tripping breakers.

• Water leaking near electrical components.

• Unusual or extremely loud equipment noises.

• Equipment that appears damaged.

• A problem that requires removing equipment panels or working with gas, electrical, refrigerant, or internal components.

For HVAC problems that aren't resolved by basic troubleshooting, call or text Sun Services at 269-684-3898.