AC running but no cool air? Walk through these 12 causes, from dead-simple filter swaps to refrigerant leaks, and figure out what’s going on before calling a tech.
Serving Portland, Beaverton, Lake Oswego, West Linn, and the greater metro area since 2008.
Owner & Lead HVAC Technician
Portland Tip: Our heat waves (80-100°F) put extra strain on AC systems. Regular maintenance prevents failures during peak summer months.
Nothing disrupts your comfort quite like an air conditioner that's running but not cooling your Portland home. After 18 years diagnosing thousands of AC systems throughout the Portland metro area, we've seen every possible cooling problem-from simple filter issues to major compressor failures.
Portland's climate presents unique challenges for AC systems. Our dry summers with occasional heat waves (temperatures can spike to 90-100°F) mean systems work harder than in humid climates. Meanwhile, our mild but variable weather means many homeowners don't maintain their AC units regularly, leading to unexpected failures when you need cooling most.
Below I'll walk through the 12 most common reasons your AC isn't cooling, with clear steps for what you can handle yourself and when it's time to call a tech. Each section includes Portland-specific context, typical repair costs, and prevention tips. For a deeper dive into heat-wave scenarios and professional diagnostic steps, see our Portland summer cooling troubleshooting guide.
Your air filter traps dust, pollen, and debris from the air. When clogged, it restricts airflow across the evaporator coil, preventing proper heat exchange. The coil stays too warm, so the system works harder but cools less effectively.
$5-20 for replacement filter
Change filters monthly from May-October due to high pollen and cottonwood seed season. Portland's dry climate means less visible dust but still heavy filter loading.
Refrigerant leaks occur due to corrosion, vibration damage, or poor installation. Leaks are common in systems 10+ years old or those exposed to Portland's weather extremes. Low refrigerant pressure causes the evaporator coil to get too cold, reducing cooling capacity.
EPA certification required to handle refrigerant. Never attempt DIY refrigerant work.
$200-
Common in older Portland homes (pre-2000) with corroded copper lines. Heat waves accelerate corrosion. Regular maintenance catches leaks early.
The evaporator coil freezes when airflow is restricted or refrigerant is low. Ice prevents heat transfer, stopping cooling completely. As ice melts, it can cause water damage to your home.
Warning: Never chip ice off coil - can damage aluminum fins permanently.
$189 diagnostic + repair of underlying cause
Due to space constraints, here are the remaining 9 causes with key details:
Grass clippings, cottonwood seeds block condenser coil. Hose off monthly during Portland's pollen season.
Dead batteries, wrong location, or faulty sensor. Check settings first - ensure on "COOL" mode.
Cools too fast, doesn't dehumidify. Common in poorly designed systems.
20-30% cooling loss in leaky ducts. Portland homes pre-1980 often affected.
Failed capacitor or contactor. Hum, click, or no start. Professional electrical work.
Outdoor fan runs but compressor doesn't. Age or overheating. Often means replacement is more cost-effective than repair, see our AC replacement cost guide.
No air flow over coil. Motor burnout from dirt/debris. $200-500 repair.
Stuck in heating mode. Blowing hot air. Valve replacement needed.
Portland 95-100°F days overwhelm undersized systems. Add shade, raise thermostat to 78°F.
Annual professional maintenance costs $100-150 but prevents $1,000+ repair bills and ensures reliable cooling during Portland's heat waves. See the full HVAC preventative maintenance cost breakdown in our plan options.
Same-day AC diagnostic and repair in Portland metro. Free estimates on repairs.
The most common reasons are dirty air filter (80% of cases), low refrigerant from leaks, frozen evaporator coil, dirty outdoor unit, or thermostat issues. Check the filter first, then outdoor unit. If problems persist, call a professional.
Costs vary by issue: Air filter replacement $5-20, thermostat $50-300, capacitor $150-400, refrigerant leak repair $200-500, compressor replacement $1,500-2,500. Professional diagnostic is $189, applied to the repair if you go ahead.
Yes, a dirty air filter is the #1 cause of AC problems. It restricts airflow over the evaporator coil, reducing cooling capacity by up to 50%. Change filters monthly during cooling season.
During Portland heat waves, systems work harder. Common causes: oversized unit cycles too fast, dirty coils, low refrigerant, or thermostat issues. Don't set below 78°F to avoid compressor stress.
Signs include ice on copper lines, hissing sounds, gradually worsening cooling, or warm air at vents. Only EPA-certified technicians can handle refrigerant. Cost: $200-500 to find and refill leak.
A few recent Google reviews from homeowners across the metro. We don't edit them.
Phil did a great job of carefully examining all the components of our almost 20 year old HVAC system. He took detailed photos and videos to show me the status. And he didn’t try to sell me anything else! Great experience 10/10System inspection
Efficiency Heating and Cooling came out to our home to do general maintenance on our furnace and heat pump, and also level our heat pump. Tristan was our technician. His work was efficient and thorough. He explained everything he did and told me what Efficiency H&C had to offering the way of maintenance programs. I am very happy with the services we received.Furnace & heat pump maintenance
This was my first time working with this company, and it was an amazing experience! Wayne was super personable, and explained things thoroughly and transparently. The cost was reasonable and that was with the maintenance membership program we joined. Highly recommend this business!Maintenance membership
I definitely recommend Efficiency! On this year's hottest day my AC quit working and Efficiency was able to send a technician right out. He fixed it quickly (luckily it was not a major issue) and now I'm basking in cool air. Thank you so much!AC repair
Tristan was very thorough with diagnosing the issues with my system and walked me through them so I could better understand my options for repair. We’ve had a few HVAC techs look at our system over the last decade or so, and Tristan was by far the best.System diagnosis
Jason came out for an estimate for a heat pump for my house. He listened to what I was looking for function-wise, evaluated the property, gave me a quote with 4 options, and explained the pros and cons of each. He was thorough, friendly, and not at all condescending (women, if you know, you know). Very professional.Heat pump estimate
I bought a furnace from these folks over 10 years ago and was very impressed with their work. I've had them tune up my furnace every year since and it's still the great quality and friendly service. They are dependable and knowledgeable every time I deal with them. I highly recommend them.Furnace install & tune-ups
Efficiency Heating and Cooling is a great company to work with. They gave me multiple options based on personal wants/needs with my 100+ year old house and were patient helping educate me and navigate to a decision. They were prompt, scheduling was easy, very professional, knowledgeable, and walked through with me how my system works once the job was complete. Couldn’t be happier from beginning to end and would heartily recommend them!100+ year old home
Called so many companies to find someone who did duct work beyond cleaning (I had a leak in the duct) and.so glad I got a hold of these guys. Professional, fast, and thorough. Great all around!Duct leak repair
Hire them immediately! Super fair pricing, great service. My Technician, Tristian was communicative and thorough. I tried hiring another company prior and they had me pre-pay, after tons of no shows and shoddy work followed by more no shows I demanded my money back and happily gave it to Efficiency Heating and Cooling.HVAC service
Tristan was very professional. He was on time and explained everything thoroughly. I appreciated the no pressure conversation of future work that could be done with my heating system.Heating system service
What a great experience with Efficiency. From the estimate process to installation, they made everything seamless and easy. When we hit an unexpected snag during installation, they kept us well informed about what was going on how it might affect the timeline. They got everything done and the system is working great!System installation
Two tune-ups a year, priority scheduling and 15% off repairs. No contract, cancel anytime.
Month-to-month · No long-term contract · Covers one system; add more for a discount
You'll talk to someone in our Milwaukie office, not a call center. We'll get a tech out and give you the price before any work starts.
(503) 698-5588Rather talk to someone?
