971-351-4414Why Your AC Isn’t Cooling: Top Portland AC Repair Calls
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7 Common reasons why your AC isn’t cooling in Portland
1. Dirty or clogged air filters
One of the most common reasons why your AC isn’t cooling is a dirty filter. Dust and debris block airflow, forcing the system to work harder while cooling less. Replace or clean filters every 1–3 months during cooling season to keep air moving and protect components. Quick Fix: Check your filter first. If airflow improves, you’ve solved the problem. If not, it’s time to look deeper.2. Low refrigerant levels
Your AC relies on refrigerant to absorb heat. If levels drop due to a leak, the system can’t keep your home cool. Signs include hissing noises, ice on coils, and warm air from vents. Refrigerant handling is regulated—this is a job for an EPA-certified technician. Why this matters: Refrigerant issues require a licensed HVAC technician. This is often the underlying reason why your AC isn’t cooling properly.3. Thermostat issues
A miscalibrated or misconfigured thermostat can make it seem like your AC isn’t cooling even when the system runs. Confirm cooling mode, setpoint, and batteries. If it still misreads, the sensor or wiring may need professional attention. Pro Tip: Make sure it’s set to “cool” and below your current room temperature. If problems continue, it may be a wiring or sensor issue best left to professionals.4. Frozen evaporator coils
Restricted airflow or low refrigerant can freeze the evaporator coil, stopping heat transfer. You may see water after thawing. Turn the system off to defrost; if the coil refreezes, schedule service. Running with a frozen coil risks compressor damage. What to do: Turn the system off and call Cornel’s for service. Running your AC with frozen coils can cause permanent damage.5. Blocked condenser (outdoor unit)
The outdoor unit must release heat. Leaves, dirt, or nearby objects can choke airflow and may be why your AC isn’t cooling at all. Clear debris and gently rinse fins. If performance doesn’t improve, a technician should inspect the fan and electrical components. Solution: Clear debris around the unit and gently hose off visible dirt. If cooling still doesn’t return, it’s time for a technician inspection.6. Electrical or sensor failures
Faulty capacitors, contactors, or sensors disrupt communication between the thermostat, blower, and compressor. These issues often explain why your AC isn’t cooling despite running. Electrical repairs aren’t DIY—book a licensed HVAC technician. Warning: Electrical repairs are not DIY-friendly. For safety and reliability, call a licensed HVAC technician.7. Undersized or aging system
Units over 10–15 years old or sized too small for the home may never keep up in Portland heat. Rising energy bills and frequent repairs suggest it’s time to consider a modern, efficient replacement installed by Cornel’s. We are licensed Daikin Pro Installers—certified to provide expert installation, repair, and maintenance of Daikin’s premium HVAC systems. Consider This: A modern Daikin system, installed by Cornel’s to deliver higher efficiency, quieter operation, and better comfort control.Quick reference table
| Problem | DIY fix | When to call Cornel’s |
|---|---|---|
| Dirty filter | Replace/clean filter | Airflow still weak after change |
| Low refrigerant | None | Always (EPA 608 certified tech) |
| Thermostat issue | Check mode, setpoint, batteries | Calibration/wiring problems persist |
| Frozen coils | Shut off, let thaw | Refreezes or leaks return |
| Blocked condenser | Clear debris, rinse fins | Cooling still inadequate |
| Electrical/sensor fault | None | No starts, short cycling, or tripping |
| Old/undersized unit | None | Repair vs. replace guidance |
🥶 Still wondering why your AC isn’t cooling? Schedule an AC repair with Cornel’s today.
FAQs: why your AC isn’t cooling
Why is my AC running but not cooling?
Clogged filters, low refrigerant, or frozen coils are the usual causes. Start by replacing the filter. If the system still doesn’t cool, a licensed technician can test refrigerant, airflow, and controls to pinpoint the issue quickly.
How do I know if my AC needs refrigerant?
Warm supply air, ice on the evaporator, and hissing at the lineset are common signs. Because leaks harm performance and the environment, only EPA-certified techs should test, repair, and recharge the system.
Can dirty filters really stop cooling?
Yes. Restricted airflow is the #1 reason homeowners ask why their AC isn’t cooling. Replace filters every 1–3 months (more often with pets or pollen) to protect the coil and maintain comfort.
Why are some rooms cool and others warm?
Uneven cooling often points to duct leaks, blocked vents, or an undersized system. Cornel’s can test duct pressure, seal leaks, and balance airflow so every room reaches the setpoint.
When should I replace instead of repair?
If your system is 12–15 years old and repairs are frequent, replacement usually lowers bills and improves comfort. New Daikin systems installed by Cornel’s deliver higher efficiency and quieter operation.
🥵 Don’t wait for the next heat wave. Book your AC service with Cornel’s now.
⚠️ Safety note: Still don’t know why your AC isn’t cooling? Contact a licensed HVAC professional.
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- Last summer, we started the process of finding the new heating and air conditioning system for our home. It was not an easy process with competing technologies … view more and vendors. It took us a long time to make the decision. My background is in mechanical engineering. And so when I spoke to Michael at Cornel I knew I was talking to someone with a strong technical background and a lot of knowledge about what type of equipment is available today. Our house is approximately 3800 ft.² and so we wanted a unit that was efficient And reliable. Cornel Recommended the Diakin variable displacement heat pump. This pump offers additional power efficiency and so lowers the cost of operation. The installation took only a few days, and the quality of the work was very professional. This last winter was the most comfortable we’ve had in years and when it turned 90 degrees a few weeks ago it worked perfectly. So if you’re looking for a unit to heat and cool your home you owe it to yourself to give Michael at Cornel’s Plumbing and Air Conditioning. And we got a great deal too!
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I once had the chance to have Cornel himself come to my house and you can tell that their company culture is built from the top down. He is one of the most helpful and knowledgeable people I’ve met on these issues.
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For anyone in need of emergency plumbing, AC installation, or heating system maintenance, I highly recommend Cornel’s. They offer fast, dependable service at a deserved price. I’ll definitely be using them for all my future HVAC and plumbing needs. Cornel’s gives me peace of mind.
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