Arlington HVAC Tips for Troubleshooting Furnaces

Arlington HVAC Tips for Troubleshooting Furnaces

Fortunately for Arlington homeowners, the winter of 2016 has been, for the most part, pretty darn warm (knock on wood). There’s still some cold days ahead, however, and just in case you’re not getting the performance out of the heating system you expect, here are a few problems areas to investigate.

It used to be that problems with older furnaces often started with a troublesome pilot light. That you could fix yourself.

Modern gas furnaces are both more efficient and complicated from those of 10 or more years ago. Smart systems involve auto-test air inducers, electronic ignition sensors, pressure switches, and exhaust flow monitoring. These can require professional assessment, necessitating a call to your Arlington heating, ventilation, and air conditioning (HVAC) contractor.

In this post we look at common problems and furnace repairs you may need to make with a conventional furnace. At the end of the post we take a quick look at repairing high efficiency condensing furnaces.


Conventional Furnaces

Problem: Gas Furnace Produces No Heat

Possible Causes

  • Thermostat set too low and not calling for heat (Check thermostat is in heat mode and has appropriate setting.)
  • Thermostat not working (Try moving settings up or down by several degrees, listen for unit to start working, check a register for air flow; clean thermostat contacts if it’s non-digital; make sure battery is not dead — this happens more than you think.)
  • Circuit breaker or fuse controlling the furnace is tripped or blown (images) (what to do)
  • Natural gas or propane control valve is closed (Do you know where this valve is located? If so, check to see if it is open or closed. If there is an issue, call your Arlington HVAC contractor to discuss. He may refer you to the natural gas company you receive service from.)
  • Pilot light is out (non-electronic ignition) (YouTube video)
  • Hot surface ignition problem, intermittent pilot ignition problem (You can troubleshoot and repair these yourself but you might prefer calling your Arlington HVAC service or repair tech.)

Problem: Gas Furnace Does Not Produce Enough Heat

Possible Causes

  • Dirty furnace air filter (images) (replace)
  • Gas burners may be dirty (images) or need adjustment (You may want to call your Arlington contractor initially, but while the service or repair tech is cleaning and making adjustments, observe the process and ask questions — it might be something you can take care of it if happens again.)
  • Obstructed air flow to combustion air chamber (Ensure furnace has adequate combustion air — see comment above.)

Problem: Gas Furnace Turns On and Off Too Quickly

Possible Causes

  • Dirty furnace air filter (Replace filter, something you should be doing regularly.)
  • Blower motor problem (Oil blower motor lubrication ports, usually at the end of the shaft; check for proper belt tension, belt depresses about one inch at center; tighten belt; replace frayed belt. You may prefer calling an HVAC contractor in the Arlington for blower motor issues.)
  • Thermostat problem — heat anticipator (what this is)

Problem: Blower Does Not Turn Off

Possible Causes

  • Thermostat set to continuous operation (Inspect thermostat, change fan setting.)
  • Faulty fan limit control switch on furnace (Call service or repair tech and have replaced.)

Problem: Gas Furnace is Noisy

Possible Causes

  • High-pitched “squealing” sound may be caused by slipping blower belt or motor or shaft bearings needing oil.
  • Low-pitched “rumbling” may be caused by poorly adjusted pilot light if this problem occurs with the burners off.
  • Low-pitched “rumbling” may be caused by dirty gas burners if this problem occurs with the burners on.
  • For these issue you probably will need to call an HVAC service or repair tech in Arlington.

Problem: Furnace Pilot is Out

Possible Causes


Electronic Ignition Furnaces

Newer furnaces do not rely on a standing pilot (what these look like) to ignite gas burners. Electronic ignition occurs one of two ways — intermittent pilot (images) or hot surface ignition (images).

The main difference between a standard furnace and a high efficiency condensing furnace is the heat exchanger technology used to extract heat from the combustion process. As a result, these have a few more troubleshooting considerations.

Problem: Weak Flame or Vent Obstruction

Check to see if the furnace combustion problem is caused by an obstructed air supply pipe by removing the burner compartment cover which will provide free air flow to the combustion chamber.

Check for obstructions in the air intake vent pipe such as leaves or nests. Clean out with a sink auger (images), a common plumber’s tool.

If this is too much for you, call a service or repair tech in Arlington, Fort Worth, or Dallas.

Weak Flame, Exhaust Gas Recirculation

Direct vent two-pipe systems can have air intake and exhaust vents improperly installed outside the home, which causes “short circuiting.” The air intake and exhaust fans may be installed too closely and exhaust vent gases (water vapor, carbon dioxide and carbon monoxide) are drawn back into the combustion air intake vent. Since the fresh air combustion intake has been compromised with exhaust gases, air reaching the furnace does not have enough clean oxygen for proper combustion.

No Ignition — Clogged Condensate Drain

Additional reasons for no ignition is a clogged flue condensate line. It will often trip the furnace’s pressure switch. If the drain is clogged by debris, improper draining, or by frozen condensate, the pressure switch will not allow for normal operation. Ignition problems may be intermittent and can start and stop as the restricted air flow drains away over time but can reappear if the problem is not fixed.

No Ignition – Clogged Flue Vent

The pressure switch can be tripped by an obstructed exhaust flue gas vent pipe. A sagging or improperly sloped exhaust vent can collect condensate water and restrict air flow resulting in a tripped pressure switch.


What to do about uneven heating.