AC Not Cooling? 12 Causes and Fixes

Airflow: the first thing to check

• Closed or blocked registers and returns
• Dirty evaporator coil or condenser coil
• Failing blower motor or a slow fan
• Crushed or disconnected ductwork
• Dirty or clogged filter

Electrical causes

• Wiring or thermostat faults
• Failed control board or transformer
• Tripped breaker or blown fuse
• Failed run or start capacitor
• Pitted or stuck contactor

Refrigerant and compressor

When the charge is low, the AC blows air that is only slightly cool and the coil may freeze. When the compressor is failing, it can hum, trip the breaker or run with no cooling. A certified technician under EPA Section 608 must handle either.

Drainage and safety switches

The float switch turns the system off to prevent water damage when a condensate drain is clogged. Clearing the drain and resetting the switch gets the system running again, and adding a cleanout helps stop repeats.

Symptom to cause

A checklist for this week

• Write down any noises or smells
• Clear the outdoor unit of debris
• Inspect the drain line outlet and the area around the air handler for water
• Replace the filter and note the date
• Book a tune-up if it has been more than a year
• Test the thermostat and schedule

Myths and facts

• Myth: a bigger AC is always better. Fact: oversizing causes short cycling and humidity problems.
• Myth: closing vents saves energy. Fact: it raises duct pressure and can cause leaks and noise.
• Myth: set the thermostat very low to cool faster. Fact: the AC cools at a steady rate and just runs longer.
• Myth: maintenance is optional. Fact: dirty coils and weak capacitors cause many summer failures.
• Myth: refrigerant is used up. Fact: low refrigerant means a leak.

HVAC terms explained

• Superheat and subcooling: readings that show whether the refrigerant charge is correct
• Condensate drain: the line that carries moisture out of the house
• Contactor: the switch that sends power to the outdoor unit
• Condenser coil: the outdoor coil where heat is released
• EPA Section 608: the certification required to handle refrigerants
• Capacitor: stores charge to start and run the compressor and fan motors
• Static pressure: a measure of airflow resistance in the ducts
• Evaporator coil: the indoor coil where refrigerant absorbs heat from the air

Ducts, airflow and comfort

Comfort depends on airflow as much as on cooling capacity. Leaky ducts, undersized returns and blocked registers cause hot rooms even when the system is sound. A technician who measures static pressure and airflow, not just refrigerant pressures, will find these problems.

What shapes the written scope

Two AC calls that sound alike can be very different jobs. The written scope should say what the technician found and which of these factors applied.

Have the provider show the diagnostic and the repair as separate items, and list any parts, labor or follow-up that are left out.

• Access to the air handler in the attic or closet and to the outdoor unit
• Whether the fault is an electrical part, an airflow problem, a refrigerant leak or a drainage problem
• Whether the ductwork, return air or thermostat contributes to the problem
• The age, tonnage and refrigerant type of the system
• Warranty status of the parts and whether the equipment is registered with the manufacturer

Safety and rules to know

Three hazards share one machine in an air conditioner: high-voltage electricity, pressurized refrigerant and moving parts. Opening electrical panels, bridging contactors and adding refrigerant are not jobs for homeowners, and capacitors can keep a charge after the power is off.

Certification under EPA Section 608 is required in the United States for anyone buying or handling refrigerant, which must be recovered instead of vented. Request the technician's certification and confirm the contractor's licence through Texas Department of Licensing and Regulation (A/C contractor license).

Questions to ask before approving a repair

• What failed, how did you confirm it and can you show me the part or the reading?
• What are my options: repair now, repair and monitor, or replace?
• Will you give me the findings and the scope in writing before work starts?
• How old is the system and which refrigerant does it use?
• Is this the cause or a symptom of something else, such as low airflow or a leak?

Prepare your Garland home before the technician arrives

• Check that the outdoor disconnect and the breaker are on, but do not open electrical panels
• Replace or check the filter, and clear furniture from the return grille and the air handler
• Set the thermostat to cool and note what it shows and what the house temperature is
• Clear weeds, leaves and debris from around the outdoor unit
• Write down the sounds, smells, leaks or ice you have noticed, and when

When to call a professional

Pick up the phone if the system will not start, if ice or water shows up, if the same problem comes back after your own checks, if you hear grinding or banging, or if anyone at home is vulnerable to heat or cold. Call Now at the top of the page puts you through once you describe what the system is doing: an independent HVAC contractor covering your ZIP code confirms the address and diagnoses the system in person.

What this means for a home in Garland

Dallas County suburb of roughly 250,000 east of Dallas, next to Lake Ray Hubbard and Rowlett. Summers regularly reach the upper 90s and 100s, so AC runs almost continuously from June to September.

Housing from the 1960s to the 1980s often has attic ductwork and older systems, including R-22 era equipment. Clay soil can shift and tilt condenser pads. Use these local details when you compare advice, and ask any technician how they apply to your system and your house.

Getting help in Garland and nearby cities

Air Conditioning Repair Garland connects you with independent HVAC contractors covering 9 ZIP codes in Garland, Texas: 75040, 75041, 75042, 75043, 75044, 75045, 75046, 75047, 75049. Requests also reach providers serving Rowlett, Sachse, Richardson, Plano and Wylie. Coverage is confirmed address by address.

Use Call Now at the top of the page and describe what you found. The contractor confirms your address, inspects the system and puts the scope in writing.

Keep reading

Related pages for Garland homeowners: How to Lower Cooling Bills; AC Not Cooling; Frozen AC Coil: Why It Happens and What to Do; AC Repair or Replace? A Decision Guide for Garland. For the area list, see the service areas page.

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