AC not cooling causes in Memphis, TN fall into five groups: airflow, electrical parts, refrigerant, drainage and controls. Work through them in order, then use Call Now if the system still does not cool. You will be connected with an independent HVAC contractor serving 59 ZIP codes around Memphis.
Airflow: the first thing to check
- Failing blower motor or a slow fan
- Dirty or clogged filter
- Closed or blocked registers and returns
- Crushed or disconnected ductwork
- Dirty evaporator coil or condenser coil
Electrical causes
- Failed run or start capacitor
- Tripped breaker or blown fuse
- Pitted or stuck contactor
- Wiring or thermostat faults
- Failed control board or transformer
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
A clogged condensate drain can trip the float switch, which turns off the system to prevent water damage. Clearing the drain and resetting the switch restores operation, and a cleanout helps prevent repeats.
Symptom to cause
| What you notice | Common cause |
|---|---|
| Warm air from vents | Low refrigerant, failed compressor or a dirty coil |
| Weak airflow | Dirty filter, blower or duct problem |
| Outdoor unit not running | Capacitor, contactor, breaker or safety switch |
| Ice on lines | Airflow or refrigerant problem |
| Water around the unit | Clogged drain or frozen coil melting |
HVAC terms explained
- Static pressure: a measure of airflow resistance in the ducts
- Contactor: the switch that sends power to the outdoor unit
- Capacitor: stores charge to start and run the compressor and fan motors
- Evaporator coil: the indoor coil where refrigerant absorbs heat from the air
- EPA Section 608: the certification required to handle refrigerants
- Superheat and subcooling: readings that show whether the refrigerant charge is correct
- Condenser coil: the outdoor coil where heat is released
- Condensate drain: the line that carries moisture out of the house
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.
A checklist for this week
- Clear the outdoor unit of debris
- Inspect the drain line outlet and the area around the air handler for water
- Book a tune-up if it has been more than a year
- Test the thermostat and schedule
- Write down any noises or smells
- Check supply and return registers
Myths and facts
- Myth: maintenance is optional. Fact: dirty coils and weak capacitors cause many summer failures.
- Myth: a bigger AC is always better. Fact: oversizing causes short cycling and humidity problems.
- Myth: set the thermostat very low to cool faster. Fact: the AC cools at a steady rate and just runs longer.
- Myth: refrigerant is used up. Fact: low refrigerant means a leak.
- Myth: closing vents saves energy. Fact: it raises duct pressure and can cause leaks and noise.
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.
- Whether the ductwork, return air or thermostat contributes to the problem
- The age, tonnage and refrigerant type of the system
- 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
- 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.
In the United States, anyone who buys or handles refrigerant must be certified under EPA Section 608, and refrigerant must be recovered and not vented. Ask the technician for their certification and check the contractor's licence with Tennessee Board for Licensing Contractors (HVAC classifications).
Questions to ask before approving a repair
- Will you give me the findings and the scope in writing before work starts?
- What are my options: repair now, repair and monitor, or replace?
- What does the repair warranty cover and for how long?
- How old is the system and which refrigerant does it use?
- What failed, how did you confirm it and can you show me the part or the reading?
Prepare your Memphis home before the technician arrives
- Check that the outdoor disconnect and the breaker are on, but do not open electrical panels
- Write down the sounds, smells, leaks or ice you have noticed, and when
- 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
- Replace or check the filter, and clear furniture from the return grille and the air handler
When to call a professional
Several situations call for a contractor: a system that will not start, ice or water, a problem that returns after your own checks, grinding or banging noises, or anyone in the house who is vulnerable to heat or cold. Use Call Now at the top of the page, describe what the system is doing, and you will reach an independent HVAC contractor who covers your ZIP code, confirms the address and diagnoses the system in person.
What this means for a home in Memphis
Hot, humid Mid-South summers with heat indexes often above 100 degrees; winters can bring ice storms. Humidity drives condensate drain clogs, sweating ducts, and mold in air handlers.
Memphis Light, Gas and Water (MLGW) is the local utility. Older homes in Midtown, Cooper-Young, Binghampton, and Whitehaven; newer homes in Cordova, Collierville, Germantown, and Bartlett. Bring these local details into any comparison of advice, and ask each technician how they apply to your system and your house.
Getting help in Memphis and nearby cities
Independent HVAC contractors covering 59 ZIP codes in Memphis, Tennessee are reached through Air Conditioning Repair Memphis: 37501, 37544, 38101, 38103, 38104, 38105, 38106, 38107, 38108, 38109. Providers who serve Ellendale, Germantown, Cordova and Collierville can also receive requests. Each address is confirmed separately.
Start with Call Now at the top of the page and say what you have found. The contractor checks your address, looks over the system and gives you the scope in writing.
Keep reading
Related pages for Memphis homeowners: AC Not Cooling; How to Lower Cooling Bills; SEER2 Explained for Memphis Homeowners; Summer HVAC Checklist for Memphis. For the area list, see the service areas page.
Common questions about AC not cooling? 12 causes and fixes
Why is my AC blowing warm air?
Low refrigerant, a failed compressor, a dirty coil or a wrongly set thermostat are the common causes.
Can a dirty filter stop my AC from cooling?
It does; airflow drops and the coil can freeze.
What if the outdoor unit does not start?
Look at the breaker and the disconnect, and if the unit still will not start, call for service.
Does the thermostat matter?
Yes, since dead batteries or the wrong settings can stop the system.
Is it worth repairing?
It varies with the cause, how old the system is and what the warranty says.
Can low refrigerant be topped up?
Not until the leak has been found and repaired.