HVAC Troubleshooting Guide

At Virginia Mechanical Heating & Air Conditioning, our priority is keeping your heating and cooling systems operating effectively. If you are experiencing problems with your equipment, we have prepared this HVAC troubleshooting guide for you to review before calling.


Before calling for service, we encourage you to follow the steps below related to your particular equipment and issue. In some cases it may prevent the need for a service call or help us diagnose your problem faster.


HVAC Troubleshooting
Air Conditioner Issues

Problem: No Cooling

  • On your thermostat, ensure that the temperature setting is set below the current room temperature by lowering it to the coolest possible setting.
  • Make sure the thermostat system switch is in the COOL or AUTO position.
  • If your air conditioning system turns on, but you are experiencing low air flow from your vents, check your air filter. Extremely dirty air filters can block air flow.
  • Check your vents to ensure they are open and free from obstructions.
  • Check the power disconnect switch by each unit and ensure they are set to ON.
  • Check your fuses/breaker at your electrical panel and ensure they are set to ON.
Heat Pump Issues

Problem: No Cooling

  • On your thermostat, ensure that the temperature setting is set below the current room temperature by lowering it to the coolest possible setting.
  • Make sure the thermostat system switch is in the ON or AUTO position. The fan switch should be set to ON for continuous airflow or AUTO if you want the blower to operate only while the heat pump is operating.
  • If your heat pump system turns on, but you are experiencing low air flow from your vents, check your air filter. Extremely dirty air filters can block air flow.
  • Check your vents to ensure they are open and free from obstructions.
  • Check the power disconnect switch by each unit and ensure they are set to ON.
  • Check your fuses/breaker at your electrical panel and ensure they are set to ON.

Problem: No Heating

  • On your thermostat, ensure that the temperature setting is set above the current room temperature by raising it to the highest possible setting.
  • Make sure the thermostat system switch is in the HEAT or AUTO position.
  • If your heat pump system turns on, but you are experiencing low air flow from your vents, check your air filter. Extremely dirty air filters can block air flow.
  • Check your vents to ensure they are open and free from obstructions.
  • Check the power disconnect switch by each unit and ensure they are set to ON.
  • Check your fuses/breaker at your electrical panel and ensure they are set to ON.
Heating System Issues

Problem: No Heating

  • On your thermostat, ensure that the temperature setting is set above the current room temperature by raising it to the highest possible setting.
  • Make sure the thermostat system switch is in the HEAT or AUTO position.
  • If your furnace system turns on, but you are experiencing low air flow from your vents, check your air filter. Extremely dirty air filters can block air flow.
  • Check your vents to ensure they are open and free from obstructions.
  • Check the power disconnect switch by each unit and ensure they are set to ON.
  • Check your fuses/breaker at your electrical panel and ensure they are set to ON.
  • Check the gas control valve to the furnace to ensure it's in the open position.
  • For furnaces with gas ignition, check the pilot light.