Heating and Cooling Troubleshooting Guide

Check the Following Common Equipment Problems Before you Call!

At Clark Heating and Cooling, we specialize in air conditioning service and repair for your home and business. Read more below on what problems you could be experiencing. If you'd like to schedule an appointment with one of our specialists, call us today and we will coordinate around your busy schedule to fit your needs. 

In some cases, your problem may not require a technician so we have provided some information that could be helpful in saving you time and money.  However, if you find that these solutions do not fix your issue, give us a call, we will be more than happy to come out and assess the situation and provide you quality service.
We’re here to help, but we understand that families are on a budget and if this troubleshooting guide can help you “do it yourself” and avoid the cost of a service repair, then we’ve got yet another SATISFIED CUSTOMER! And that means you’ll call us when you can’t fix it yourself. 


Common Gas Furnace Problems

Gas Furnace Isn't Producing Heat

Possible Causes & Solutions: 
  • Thermostat isn't set properly and isn't calling for more heat
    • Solution: Ensure that the thermostat is set to "heat" and is set to the correct temperature
  • Thermostat is broken
    • Solution: Move the temperature up or down a few notches to see if it triggers the system
  • Circuit breaker is blown or not working properly
    • Solution: Reset the circuit breaker that is blown or replace the blown fuse
  • Control valve is closed
    • Solution: Open the control valve
  • Pilot light is out
    • Solution: Relight the pilot light

Gas Furnace Isn't Producing Enough Heat

Possible Causes & Solutions: 
  • Air Filter is dirty
    • Solution: Replace the air filter
  • Gas burners could need adjusted or could be dirty
    • Solution: Call furnace service technician to have the burners cleaned or adjusted
  • Air flow obstruction to combustion air chamber
    • Solution: Ensure the furnace has sufficient air flow

Gas Furnace Turns On and Off A Lot

Possible Causes & Solutions: 
  • Air Filter is dirty
    • Solution: Replace the air filter
  • Blower motor could be going out
    • Solution: Oil the blower motor with lightweight oil
  • Thermostat could have a problem
    • Solution: Adjust thermostat heat anticipator 

Gas Furnace Blower Doesn't Turn Off

Possible Causes & Solutions: 
  • Thermostats fan is set to "always on"
    • Solution: Change thermostat fan setting
  • If thermostat does not have a fan setting then the fan limit control switch could be faulty
    • Solution: Rest or replace the fan limit control switch

Gas Furnace is Noisy

Possible Causes & Solutions: 
  • Squealing sounds could indicate a slipping blower belt or motor/shaft bearings needing oil. 
    • Solution: Check that the blower belt depresses about 1" center of span. If the belt is too loose, tighten it, if it's broken, replace it. Oil the motor or shaft bearings with lightweight oil.
  • If the burner is off and there is a lower pitch rumble sound, this could be caused by a poorly adjusted pilot light. 
    • Solution: Adjust the pilot light
  • If the burner is on and there is a lower pitch rumble sound, this could be caused by dirty gas burners.
    • Solution: Call a certified technician to have the burners cleaned or adjusted.

Gas Furnace Pilot Light is Out

Possible Causes & Solutions: 
  • A pilot light can go out from a strong wind or dirty orifices
    • Solution: Relight the pilot light or clean the furnace to keep it from continuing to happen
  • The thermocouple could be malfunctioning and is shutting off the gas supply
    • Solution: Replace the thermocouple.

Common Air Conditioning Problems

Air Conditioning Isn't Working At All

Possible Causes & Solutions: 
  • Circuit breaker is blown or not working properly
    • Solution: Reset the circuit breaker that is blown or replace the blown fuse. 
  • Thermostat isn't set properly
    • Solution: Ensure that the thermostat is set to "cool" and is set about 3 degrees below your desired temperature
  • Make sure there is sufficient power going to the unit
    • Solution: Air conditioning runs on a 240-volt, check to ensure that this hasn't been turned off somehow (this is typically mounted in a metal box near the unit)
  • Faulty wiring or low battery life on the thermostat
    • Solution: Open the thermostat's cover and ensure that none of the wires appear to be pinched and are still properly connected.  Replace the batteries in the thermostat

Air Conditioner is Freezing Up

Possible Causes & Solutions: 
  • Dirty filters, coils or poorly working fans can restrict the airflow
    • Solution: Clean or replace any items that aren't working properly
  • Low refrigerant level
    • Solution: Call a service technician to have the unit recharged

Air Conditioner Blower Hums But Doesn't Run

Possible Causes & Solutions: 
  • The blower motor has probably gone bad
    • Solution: Replace the blower motor

Water is Leaking From the Air Conditioner

Possible Causes & Solutions: 
  • There is a leak at one of the plastic pipes or tubes
    • Solution: Repair or replace the pipe or tube
  • There is a block somewhere that is restricting the water's flow
    • Solution: Locate and unblock the affected area
  • The condensate pump is malfunctioning
    • Solution: Replace the condensate pump

Water is Leaking From the Air Conditioner

Possible Causes & Solutions: 
  • There is a leak at one of the plastic pipes or tubes
    • Solution: Repair or replace the pipe or tube
  • There is a block somewhere that is restricting the water's flow
    • Solution: Locate and unblock the affected area
  • The condensate pump is malfunctioning
    • Solution: Replace the condensate pump

Air Conditioner Won't Turn Off

Possible Causes & Solutions: 
  • Thermostat is malfunctioning
    • Solution: Replace the thermostat
      • To test to see if it's the thermostat, switch the thermostat to heat and see if it kicks on, if it doesn't then it's probably the thermostat
      • If it does then try removing the "yellow" wire from the thermostat
        • If the unit turns off, the thermostat is either broken or it's not wired correctly
          • Solution: Replace the thermostat
        • If the unit remains on, the contacts on the run relay (which is outside) may have welded together (as this is common overtime)
          • Solution: Replace the run relay

Heating and Cooling Equipment Checklists

Good Reminders to Check at the Start of a New Season

Here are a few reminders on things to check at the start of a new season when you are switching between your heating and cooling units.  Continue reading for additional maintenance that needs done throughout the year as well.

Gas Furnace Equipment

  1. Check to make sure that your thermostat is set in the “heat” position
  2.  Make sure that the temperature setting on the thermostat is set above (or higher than) the indoor temperature showing on the thermostat. Please note, some systems have a delay built in and heat may not start for 5 or more minutes. 
  3. Ensure that there is power to the furnace by checking the on/off switch located at the furnace (looks like a light switch), check the breakers in the electrical panel and you can also turn your thermostat fan setting from auto to “on” to see if the blower runs at all, even when there isn’t a request for heat. 
  4.  Replace the furnace filter if needed, if a furnace is “starved” of fresh air from a blocked filter, it will shut down on safety. Turn furnace off, replace filter and retry. 1” filters should be changed monthly, and 4-5” filters should be checked at 6 months and changed if needed and definitely changed once a year. This is depending on size of family, number of pets, recent remodeling etc.
  5.  If the system is running but you have not changed your filter, the filter may need to be replaced.
  6. Check all supply and return air grilles to make sure they are not blocked by furniture.

Air Conditioning Equipment Checklist

  1. Is your thermostat in the “cool” position, and have you removed any tarps or covers from the outdoor unit, prior to attempting to start it?
  2. Is your outdoor unit running? Check the breakers in the electrical panel (usually located in the garage, basement or other outside walls) Make sure they are in the “on” position for the breaker marked for the Air Conditioner or Heat Pump. Check the disconnect box (mounted outside at the unit, on the side of the house) make sure it is in the “on” position.
  3. Is the blower motor in the furnace running? (If the thermostat is in the “cool” position, the furnace blower should be running.) If not, make sure the on/off switch at the furnace is in the “on” position. It looks like a light switch on the side of the furnace. 
  4. Have you changed your filter recently? A blocked air filter can most definitely be the culprit. Depending on family size and number of animals, recent remodeling or even refinishing your hardwood floors, changing your filter can be a quick and easy fix. 1” filters should be changed monthly, 4-5” filters should be checked at 6 months and changed if needed, but most likely will last a full year. Be sure that you have changed your filter in the furnace recently. If you noticed “ice” on the indoor or outdoor units along with your dirty filter, turn the system off, change the filter, allow the system to thaw and try to run it again the next day.
  5. Check all supply and return air grilles to make sure they are not blocked by furniture.
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