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If your central air conditioner is running but not cooling, start with the thermostat, air filter, and visible obstructions around the equipment. Those are homeowner-level checks; electrical work and anything involving refrigerant belong to a qualified HVAC technician. An annual pre-season service visit can catch airflow, drainage, coil, and refrigerant problems before they turn into larger repairs.
Why is my AC running but not cooling?
Begin with the simplest checks. Confirm that the thermostat is set to cooling and that its setpoint is below the room temperature. Inspect the air filter and look for leaves or other debris blocking the outdoor unit. Do not remove equipment panels or reach inside either unit.
A dirty filter or obstructed airflow can limit cooling without indicating a refrigerant problem. ENERGY STAR says airflow problems can reduce system efficiency by up to 15 percent; the organization does not state a publication year for that figure on its maintenance guidance. If these basic checks do not resolve the issue, have a technician diagnose it rather than assuming the system needs refrigerant.
How often should I change my AC filter?
Check the filter monthly, especially during months when the system runs heavily. Change a disposable filter when it is dirty and at least every three months, following the system’s instructions. Confirm the replacement filter’s size and type against the existing filter and the equipment or owner’s manual; an incorrect filter may not fit or suit the system. ENERGY STAR provides this advice in its central air conditioner maintenance guidance.
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- MAKE YOUR HOME YOUR SANCTUARY: 4-pack of 3-month pleated Filtrete 16x25x1 MERV 11 MPR 1000 AC Furnace Air Filter helps capture unwanted particles from your household air to contribute to a cleaner, fresher home environment
- COOLING SEASON READY: Keep your home cool and your air cleaner with a Filtrete AC filter (Compared to MERV minimum filter requirements)
- EXCLUSIVE TECHNOLOGY: Designed with Filtrete 3-in-1 technology to pull in and trap unwanted particles, allowing cleaner air to flow through (Compared to MERV 11 minimum filter requirements; microparticles are 0.3 – 1.0 in size)
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- CERTIFIED: This furnace filter is CERTIFIED asthma and allergy-friendly (2) and helps capture dust, lint and other allergens in your household air
Also keep leaves and other debris clear of the outdoor equipment and maintain unobstructed airflow around it. A filter check and visual cleanup are not a reason to open electrical or refrigerant compartments.
What does an AC tune-up include?
ENERGY STAR recommends an annual pre-season checkup, ideally before cooling season. Its central AC checklist describes work for a service professional, including:
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- Universally Compatible: Measuring 20" x 20" x 1", with an actual size of 19.75"x19.75" x 0.75", Simply Filters works with almost any brand. Comparable to 3M Filtrete MPR 600, Filterbuy AFB Silver, and Honey well FPR 5.
- Cleaner Air Everywhere: Our filters capture dust, mold, pet dander, and pollen in homes, offices, schools, hospitals, and commercial spaces, trapping 90% of airborne particles, promoting a healthier living environment with clean and fresh indoor air.
- Advanced Pleated Technology: With a higher pleat count than most retail, our meticulously crafted filters offer superior capture coverage, optimizing airflow and efficiency.
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- Made in USA: Our filters are made using 100% American components, including recycled materials, ensuring superior performance and quality. Experience exceptional filtration and support local manufacturing.
- Checking thermostat settings and system controls.
- Tightening electrical connections and measuring motor voltage and current.
- Lubricating moving parts.
- Checking the condensate drain, which can cause water damage and humidity problems if it is plugged.
- Cleaning the evaporator and condenser coils; dirty coils can make the system run longer and use more energy.
- Checking refrigerant charge and adjusting it if needed.
- Cleaning and adjusting blower components to support airflow.
These tasks involve system components and are not a DIY service checklist. ENERGY STAR’s maintenance page also says improper installation can reduce system efficiency by up to 30 percent; no year is stated for that figure. Nearly half of home energy use goes to heating and cooling, according to ENERGY STAR’s heating and cooling guidance, but that broad context is not a forecast of savings from a tune-up or repair.
Can I recharge my home AC myself?
No. Homeowners can inspect filters and observe symptoms, but should not open or service the refrigerant circuit. The U.S. Environmental Protection Agency (EPA) requires Section 608 certification for work that could reasonably be expected to breach that circuit and release refrigerant. EPA also says refrigerant for stationary appliances is sold only to certified technicians or their employers. Ask whether the technician has the relevant Section 608 certification and experience with the refrigerant in your specific unit.
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- MAKE YOUR HOME YOUR SANCTUARY: 2-pack of 3-month pleated Filtrete 20x25x1 MERV 11 MPR 1000 AC Furnace Air Filter helps capture unwanted particles from your household air to contribute to a cleaner, fresher home environment
- EXCLUSIVE TECHNOLOGY: Designed with Filtrete 3-in-1 technology to pull in and trap unwanted particles, allowing cleaner air to flow through
- COUNTLESS MICROPARTICLES: With a 1000 MPR and MERV 11 rating, your Filtrete Filter will help capture many microparticles from the air passing through it
- CERTIFIED: This furnace filter is CERTIFIED asthma and allergy-friendly (2) and helps capture dust, lint and other allergens in your household air
- CHANGE YOUR FILTER OFTEN: For optimal performance, make sure to change your filter at least once every 90 days
If refrigerant is suspected, ask the technician to identify and repair the leak rather than simply topping off the system. A top-off does not fix the cause, and a leak can lead to repeat service and refrigerant emissions. Check the outdoor unit’s nameplate or owner’s manual to identify its refrigerant; systems do not all use the same type. See the EPA’s homeowner guidance on residential AC and heat-pump servicing.
Do not use R-22a, also called 22a, as a substitute for HCFC-22. EPA identifies it as a highly flammable hydrocarbon blend that is not an acceptable substitute in residential AC systems designed for HCFC-22. If it contacts an ignition source, the concentration of flammable product can create a fire or explosion risk. Avoid DIY recharge cans and purported drop-in refrigerants.
Rank #4
- SIZE & COMPATIBILITY: Nominal 16x20x1 (Actual 15.75 x 19.75 x 0.75 in). Select nominal size based on your current filter's frame or measurements. Fits standard furnaces, ACs & HVAC return grilles
- ENHANCED AIR QUALITY: Merv 8 rating air filters effectively captures household irritants like lint, dust, and pollen, to help provide cleaner and healthier air in your home
- IMPROVED FURNACE EFFICIENCY: Designed to promote furnace efficiency and optimization, this furnace air filter traps particles that can cause system wear and tear
- DURABLE CONSTRUCTION & EASY INSTALL: Made with a beverage board frame and wire mesh support, this home air filter provides reliable, long-lasting performance. Insert with the airflow arrow pointing toward the furnace/blower (away from the return grille) for a snug fit
- ELECTROSTATICALLY CHARGED MATERIAL: The air filters are made with synthetic material that is electrostatically charged to attract and capture allergens as small as 3 microns
Should I repair or replace my air conditioner?
There is no single age or repair-cost rule that settles this decision for every home. EPA recommends professional evaluation when HVAC equipment is more than 10 years old or is not keeping the home comfortable. ENERGY STAR advises addressing major air leaks and duct problems before investing in new equipment, since they can contribute to comfort and efficiency problems.
For U.S. residential split systems, EPA says an existing system may be maintained and repaired throughout its useful life. Its guidance describes replacing a faulty component with a similar R-410A component as a repair in the scenario addressed. Replacing both the outdoor condensing unit and indoor coil together is treated as a new system; a whole new residential split system installed after January 1, 2026 must use refrigerant with a global warming potential (GWP) below 700. These are federal transition rules, and the contractor should confirm the system type and applicable requirements before specifying equipment. EPA says the decision should account for component availability, energy efficiency, and total maintenance costs; consult its residential and light-commercial AC transition guidance.
Best Value
- Universally Compatible: Measuring 16" x 25" x 1", with an actual size of 15.75"x24.75" x 0.75", Simply Filters works with almost any brand. Comparable to 3M Filtrete MPR 600, Filterbuy AFB Silver, and Honey well FPR 5.
- Cleaner Air Everywhere: Our filters capture dust, mold, pet dander, and pollen in homes, offices, schools, hospitals, and commercial spaces, trapping 90% of airborne particles, promoting a healthier living environment with clean and fresh indoor air.
- Advanced Pleated Technology: With a higher pleat count than most retail, our meticulously crafted filters offer superior capture coverage, optimizing airflow and efficiency.
- Long-lasting Filtration & Easy Installation: Enjoy up to 3 months of resilient filtration. Hassle-free replacement for air conditioning units or HVAC systems. Follow airflow arrows and insert into the filter slot for central units or return grilles.
- Made in USA: Our filters are made using 100% American components, including recycled materials, ensuring superior performance and quality. Experience exceptional filtration and support local manufacturing.
How do I compare AC repair contractors?
Ask each contractor to address the same points so you can compare the diagnosis and scope, not just a bottom-line number:
- Technician credentials and experience with the refrigerant used by your unit.
- The identified cause of the problem and, if there is a leak, whether the proposal includes locating and repairing it.
- What inspection, parts, labor, and follow-up are included.
- Whether the proposed component is available and compatible with your system.
- If replacement is proposed, how its cost compares with likely repair and maintenance costs and the system’s efficiency.
Ask whether the company is licensed and insured where applicable, and check for recognized HVAC installation credentials. License requirements vary by locality; ENERGY STAR offers guidance on choosing a heating and cooling contractor, but its advice is not a state-by-state licensing directory.
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