HVAC Not Working? What to Do Right Now

An HVAC failure in Douglas County can be more than just uncomfortable — it can be dangerous. At 6,000+ feet elevation, our homes lose heat faster than at sea level due to thinner air and lower atmospheric pressure. Winter temperatures regularly drop below zero, and summer highs can exceed 95°F. This guide helps you diagnose common problems, take immediate action, and know when professional help is essential.

Immediate Steps When Your HVAC Fails

Before panicking or calling for emergency service, run through these quick checks that resolve many common issues:

Step 1: Check the Thermostat

• Verify settings: Make sure it's set to “heat” or “cool” as appropriate, not “off”
• Check the fan setting: Set to “auto” for normal operation, not “on”
• Replace batteries: Many thermostat issues are simply dead batteries
• Verify temperature setpoint: Ensure the set temperature is at least 3-5 degrees above (for heat) or below (for cool) the current room temperature
• Check for blank screen: If the display is blank, there's likely a power issue

Step 2: Check the Circuit Breaker

• Locate your electrical panel and find breakers labeled “HVAC,” “furnace,” “air handler,” or “AC”
• A tripped breaker may be in a middle position — flip it fully OFF, then back ON
• If it trips again immediately, stop and call a professional (there's an electrical issue)
• Don't forget the outdoor AC disconnect box near the condenser unit

Step 3: Check the Air Filter

A severely clogged filter is one of the most common causes of HVAC failure, especially in Douglas County's dusty environment:

• Locate your filter (usually in the return air vent or at the furnace/air handler)
• If you can't see light through it, it's too dirty
• Replace with a new filter of the correct size
• After replacing, wait 30-60 minutes for the system to reset from any overheat protection shutdown

Step 4: Check the Furnace Switch

Most furnaces have an on/off switch that looks like a standard light switch, usually located on or near the furnace. It sometimes gets accidentally turned off. Verify it's in the ON position.

No Heat Troubleshooting (Furnace Issues)

If you have no heat and basic checks didn't solve the problem, here are furnace-specific issues:

Furnace Won't Start at All

• Check pilot light (older furnaces): If you have a standing pilot, it may have blown out. Follow the manufacturer's relighting instructions on the unit label
• Check ignitor (modern furnaces): Hot surface ignitors fail over time. You may see the furnace attempt to start (blower runs briefly) then shut down. This requires professional replacement
• Check gas supply: Verify other gas appliances work (stove, water heater). If nothing has gas, contact Xcel Energy
• Check error codes: Many furnaces have LED indicators that flash error codes. Note the pattern for the technician

Furnace Runs But No Heat

• Blowing cold air: The flame sensor may be dirty (common issue), preventing the burners from staying lit. The ignitor may be failing. Or the gas valve may not be opening
• Weak airflow: Clogged filter, closed vents, or a failing blower motor
• Short cycling: Furnace overheating due to airflow restrictions or a dirty flame sensor

Colorado-Specific Furnace Considerations

At Douglas County's altitude (6,000-6,600 feet), furnaces need high-altitude calibration:

• Gas furnaces require altitude-specific orifices to maintain proper combustion
• Improperly calibrated furnaces produce less heat and more carbon monoxide
• If your furnace was installed by a sea-level contractor or moved from a lower elevation, it may need recalibration
• A yellow or orange flame (instead of blue) often indicates altitude calibration issues

No Cooling Troubleshooting (AC Issues)

When your air conditioner fails during a Douglas County summer, here's what to check:

AC Won't Start

• Check the outdoor unit: The disconnect box near the condenser may be off, or the capacitor may have failed (common issue)
• Check the indoor blower: If the outdoor unit runs but no air flows inside, the blower or its capacitor may have failed
• Check for ice: Look for frost or ice on refrigerant lines near the indoor unit — this indicates a problem (see below)

AC Runs But Doesn't Cool

• Frozen evaporator coil: If ice has formed, turn off the AC and set the fan to “on” to thaw (4-6 hours). Caused by low refrigerant, restricted airflow, or a dirty coil
• Dirty condenser coil: The outdoor unit may be clogged with cottonwood seeds (a major problem in late May/early June), dirt, or debris. Gently rinse with a garden hose
• Low refrigerant: If the system is low on refrigerant, cooling capacity drops significantly. This requires professional service — refrigerant doesn't “use up,” so low levels indicate a leak

Altitude Effects on AC Performance

At Colorado's altitude, AC units face unique challenges:

• Thin air is 15-20% less efficient at transferring heat from condenser coils
• Compressors work harder to achieve the same cooling effect
• Systems sized for sea-level performance may be undersized for our altitude
• On days above 95°F, even properly sized systems may struggle to maintain temperatures

When to Call a Professional Immediately

Some situations require immediate professional attention:

• Gas smell: Evacuate first, then call Xcel's emergency line (1-800-895-2999) and 911
• Carbon monoxide alarm: Evacuate and call 911 — CO is odorless and deadly
• Burning smell: Turn off the system immediately — could indicate electrical fire or overheating
• Sparking or electrical sounds: Turn off at the breaker and call for service
• Water leaking into living space: Could indicate frozen coil, clogged drain, or cracked heat exchanger
• Extreme cold emergency: If temperatures will drop below freezing and you can't restore heat, call for emergency service to prevent frozen pipes

Staying Safe While Waiting for Repairs

No Heat Safety Tips

• Prevent frozen pipes: Open cabinet doors under sinks, let faucets drip slightly, and know your main water shutoff location
• Use space heaters safely: Keep 3 feet of clearance, never leave unattended, plug directly into outlets (not extension cords)
• Never use outdoor heaters indoors: Propane heaters, grills, and camp stoves produce carbon monoxide
• Never use your oven for heat: Gas ovens produce CO, and running any oven continuously is a fire risk
• Check on vulnerable family members: Elderly, young children, and those with health conditions are at higher risk

No Cooling Safety Tips

• Stay hydrated: At altitude, dehydration happens faster
• Use fans strategically: Ceiling fans counterclockwise, portable fans positioned to create cross-ventilation
• Close blinds: Block direct sun, especially on south and west-facing windows
• Avoid using heat-generating appliances: Ovens, dryers, and even multiple lights add to heat load
• Know the warning signs of heat illness: Heavy sweating, weakness, nausea, dizziness — seek cool environment and medical attention if severe

Preventive Maintenance Prevents Emergencies

Most HVAC emergencies can be prevented with proper maintenance:

• Change filters monthly: In Douglas County's dusty climate, this is especially important
• Schedule professional tune-ups: Heating in fall, cooling in spring
• Clean outdoor units: Remove cottonwood seeds, leaves, and debris regularly
• Test your system before peak season: Run your AC in late spring, furnace in early fall to catch problems before you need them most
• Keep vents clear: Don't block supply or return vents with furniture or rugs
• Maintain carbon monoxide detectors: Test monthly, replace batteries annually, replace units every 5-7 years

Frequently Asked Questions