AC running but not cooling your home? Learn the most common causes, troubleshooting tips, and when to call for AC repair in St. Louis.
When your air conditioner is running, but your home still feels warm, it can be frustrating—especially during the hot, humid St. Louis summer. You may hear the system operating and feel air coming from the vents, but the house simply isn’t getting cooler.
This problem is one of the most common reasons homeowners call for AC repair. Fortunately, some causes are simple to fix, while others require professional HVAC service.
Nick was great! He came right out and was able to solve the problem fairly easily. He communicated well and helped us prevent a future problem as well.
Response from the owner:Thank you for the review, Philip! We are happy to hear you had a pleasant experience working with us.
Response from the owner:Thank you, Pat, for your kind words about Giovanni; we appreciate your feedback and are glad to hear that he made a positive impression.
They have never failed to fix my hvac problems. These folks are top tier.
Response from the owner:Thank you for the wonderful feedback, Greg! We're glad to hear that you've had such positive experiences with our team. Providing timely and effective service is our priority, and we're here whenever you need us. Looking forward to assisting you again!
Giovanni was very professional, helpful, patient and helped me figure out the issue, if it was covered under warranty, and next steps. Great overall experience and much appreciated.
Response from the owner:Thank you, Amy! We're glad to hear that Giovanni provided you with such professional and helpful service. Your appreciation means a lot to us!
Always professional and thorough whenever they service our home. We have used Thomas Hoffmann Air Conditioning & Heating multiple times since we moved into our home and will continue to use them in the future.
Response from the owner:Thank you for the thoughtful review, Joe. We appreciate you and your business!
0 stars if I could. Bought a faulty (not to mention overpriced) surface igniter, called back five minutes later after installing, of course they didn’t stand behind their part. Go to Grainger instead. Same (working) part, half the price.
Response from the owner:Hi there. I am unable to locate your customer profile. Please give our office a call at 314-471-7625 so we can get this figured out for you.
From the phone to the completion of the job everyone is so polite and informative. I had Giovani as our representative and he was very informative and professional, and knew exactly what the problem was. Thanks so much.
Response from the owner:Thank you for the kind review, Frank! We appreciate you and your business.
My furnace was not working. A very nice gentleman came out this morning and fixed the problem and now I have much needed heat. He was very professional and courteous. I will definitely be using them again when the need arises.
Response from the owner:Thank you for the positive feedback! We're glad to hear that you were pleased with our prompt and friendly service. We look forward to assisting you again in the future!
I will always call Hoffmans for my air and heat needs. They were out to my daughters house that day and fixed it. It was right before the weekend storm with below zero temps the next day. They saved my daughter and grandbabies. I could never thank them more.
Response from the owner:We are so happy to hear that we could help! Thank you for the kind review.
Snow and drifting snow covered intake and out take vents causing the furnace emergency to shut off furnace. Cleaned off the driftibg/ snow off roof and vents furnace works perfect now. Thank you and great job Nick.
Response from the owner:Thanks for the great review, Scott! We appreciate your support.
5 stars! Nick was here to fix my heater within 2 hours of my call. He explained the problem to me thoroughly and got the job done quickly & professionally. Thank you so much!
Response from the owner:Thank you for the kind review, Jennifer! Glad we could help.
Extremely thorough and educational. They do a wonderful job of explaining everything and making sure I was comfortable knowing how the systems worked in my house!
Response from the owner:Thanks for the great review, Matthew! We appreciate your support.
I noticed a strange noise that I was concerned was linked to my furnace. I called Thomas Hoffman Heating & Cooling and Nick came right out. He was very thorough checking all components. Thankfully all checked out for us this visit. Definitely recommend Thomas Hoffman Heating & Cooling!
Response from the owner:Thank you so much for the kind review, Abby! We appreciate your business and look forward to servicing you in the future.
Thomas Hoffman is a wonderful company to work with. Techs are knowledgeable, personable & efficient.
Response from the owner:Thank you, Christine, for your kind words about our team; we appreciate your feedback and are glad to hear you had a positive experience!
Got a quote over the phone. Everything was explained thoroughly. Dakota, my technician arrived and on time, was very professional and knowledgeable. He didn’t try to upsell or change anything. He did a great job. We can already tell the difference since the ducts and vents were cleaned. Would recommend an use Hoffman again in the future.
Response from the owner:Happy to hear you had a pleasant experience using Thomas Hoffmann!
The technician, Ryan, was knowledgeable and helpful in identifying the issue with our mini split AC unit. They are the second company we called after issues with the first and will be using Hoffmann again.
Response from the owner:We are so happy to hear your experience with Thomas Hoffmann was pleasant. Thank you for your kind review, & we look forward to working with you in the future!
woke up to a very cold house, called Thomas Hoffmann, they were able to come out a couple of hours later and get the issue resolved. Always trust them, they have always been quick to respond and get either the heating or ac issue fixed that day. Also a great price!!!! give them 10 stars if i could, Thank You JS
Response from the owner:Thank you for the kind review, Jim. We are happy to hear that you had a positive experience working with Thomas Hoffmann!
Response from the owner:Thank you, Hank, for your wonderful feedback; we're glad you enjoyed the fast, friendly, and professional service, and we'll be sure to keep up the great work!
The technician Giovanni was excellent and on time very professional and efficient and knowledgeable of the project at hand ,gave great advice but most of all did great work đź‘Ź thank you .
Response from the owner:We are so happy to hear you had a great experience, Sam! Thank you for the review, and thank you for your business.
Very fast service, Nice young man, and personable!
Response from the owner:Thanks for the great review, Christina! We appreciate your kind words and your business.
Common Causes St. Louis Homeowners Should Know
1. Dirty Air Filter
A clogged air filter is one of the most common causes of cooling problems. When filters become dirty, airflow is restricted. This prevents the system from moving enough air across the evaporator coil to cool your home effectively. Signs of a dirty filter include:
Most homeowners should change their air filter every 1–3 months. Replacing the filter is often the first step when troubleshooting cooling issues.
2. Dirty Condenser Coils
The outdoor AC unit releases the heat removed from your home. If the condenser coil becomes covered with dirt, grass, or debris, the system cannot release heat effectively. This causes the AC to struggle to cool the house. Common signs include:
Keeping the outdoor unit clear of debris and scheduling regular maintenance helps prevent this issue.
3. Refrigerant Problems
Refrigerant is the substance that absorbs heat from your home. If refrigerant levels are low due to a leak, the AC cannot cool properly. Signs of refrigerant issues include:
AC is blowing warm air
Ice on refrigerant lines
Hissing sounds near the unit
Longer cooling cycles
Refrigerant leaks require professional repair and should always be handled by a licensed HVAC technician.
4. Leaky Ductwork
Your ductwork carries cooled air from the system throughout your home. If ducts develop leaks, cooled air may escape into the attic or crawlspace before reaching your living areas. This can result in:
Poor cooling performance
Uneven temperatures between rooms
Higher energy bills
Professional duct inspection may be needed to identify leaks.
Maintenance helps ensure your system is ready for St. Louis summer heat and humidity.
Air Conditioning Repair in St. Louis
If your air conditioner is running but not cooling, a professional diagnosis can identify the issue and restore comfort to your home. Thomas Hoffmann Air Conditioning & Heating LLC provides trusted AC repair and cooling services for homeowners throughout the St. Louis metro area. Call today to schedule AC repair:(314) 471-7625.
24/7 Service Call Now
At Thomas Hoffmann Air Conditioning & Heating, we pride ourselves on being a locally owned and operated HVAC company. With more than 30 years of experience and a master technician and mechanical engineer as our owner, we can replace, repair, and maintain your business or home’s HVAC system.
