Too Hot, Too Cold: What to do About Uneven Cooling

It’s frustrating to struggle with uneven cooling in your home during our scorching hot Arizona summers. We all want our homes to be evenly cooled for maximum comfort in hot weather.

But unfortunately, some homes may often be too hot in some rooms and too cold in others. Uneven cooling is particularly a problem in two-story homes, where the first floor stays cool while the second story is always too warm. It may also present a problem in rooms with large windows that receive much sunlight and are hard to keep cool.

Here are some possible causes of uneven cooling in your home and what you can do to fix them:

  1. Blocked vents.

Your air conditioner is meant to work with all the vents open, so you should never have more than 10% of the vents closed when running the system.

When air hits a blocked vent, it will be pushed around to the open vents, making some areas of your home overly cool while others stay warm.

Check each room to ensure all vents are open, unblocked, and dust-free.  Dirty vents will impact your indoor air quality.

Also, be sure to change your air filters regularly, as often as once a month in the summer. According to the U.S. Department of Energy, the most essential task to ensure the efficiency of your HVAC system is to change filters regularly.

Dirty filters can slow or block the airflow through your home, leading to uneven cooling.

Write the date you installed it on the new filter, so you’ll know when you last changed each one.

  1. Leaking ducts.

The ductwork in your home is a crucial part of your HVAC system, but as it’s hidden, you may be unaware of unseen damage that can cause uneven cooling.

Cracked or poorly sealed ducts not only waste energy and cost you money, they can prevent cool air from getting into your home where you need it.

If it seems cool air isn’t coming through the vents in some parts of your home even though they’re open and the A/C is on, the problem could be your ductwork.

Have your ductwork inspected and repaired by a professional, as most repairs aren’t suitable for do-it-yourself projects.

  1. A short-cycling air conditioner.

Short cycling means that the compressor runs for too short a time in each cycle to cool your home, resulting in uneven cooling.  The compressor should run for at least ten minutes per cooling cycle to adequately and evenly cool your home.

Cool air can’t reach every room if the cooling cycle isn’t long enough.

If your air conditioner is short cycling, call an HVAC pro to inspect and fix the problem, as short cycling can increase your energy bills and damage your system.

If you’ve neglected regular maintenance for your air conditioner, it’s probably not performing at its best and could be contributing to the problem of uneven cooling.

Your air conditioner needs regular, professional maintenance. Chas Roberts has a 26-point maintenance checklist to keep your A/C system running in peak condition.  It includes:

  • Check refrigerant levels
  • Inspect disconnect switch
  • Clean condenser coil
  • Test safety controls
  • Lubricate all moving parts
  • And more

Neglecting air conditioner maintenance is never cost-effective and may lead to uneven cooling and other A/C problems on the hottest days of the year.


  1. A poorly insulated attic.

The attic insulation in your home may not be sufficient to keep the upstairs rooms cool.  Cool air could escape if your attic isn’t well-insulated with insulation with the correct R-value for our region.

If that appears to be the problem, add more insulation to your attic.

  1. Your air conditioner is old.

If your air conditioner is ten years old or older, it’s near the time you’ll need to replace it. A/C units work especially hard in Arizona, as we run our systems continuously for months.

Air conditioners lose efficiency as they age, and they have to work harder to cool your home. Even a well-maintained air conditioner will decline until it eventually fails.

An aging air conditioner may be causing uneven cooling in your home.

It’s generally more cost-effective to replace an old air conditioner than to spend money repairing it.

The pros at Chas Roberts can help you choose a new, more efficient air conditioner that will cool your home for years to come.

  1. Your home may need a zoned cooling system.

A zoned cooling system uses dampers in the ductwork to precisely control airflow to predetermined zones in your home. Zoned cooling allows you to create two or more customized temperature zones in your home so you can control the temperature of each zone for comfort and improved efficiency.

With a zoned cooling system, you’ll be able to cool the upstairs rooms that never get cool enough while not wasting energy excessively cooling other rooms. Each zone in your home will have its own thermostat for precise temperature control.

One room can be a zone, or a zone can comprise an entire section of your home.  An HVAC pro can help you determine the zone configuration that best meets your needs.

You’ll no longer have to cool your entire home to one temperature with a zoned system, eliminating uneven cooling problems.

An HVAC pro can install a zoning system with a new A/C unit or your existing system.  You’ll see increased savings in energy costs with a zoned system, as you’ll have more precise temperature control for each zone in your home.

While a zoned system is a significant investment, it may be the best solution to your home’s uneven cooling problem.


Solving the problem of uneven cooling may be as simple as making sure all the vents in your home are open so air can flow freely. However, the solution that provides the best results may be a zoning system or even a new air conditioner.

A Chas Roberts HVAC pro can help you choose a solution that provides an even cool airflow where you need it, so you’ll never be too hot or too cold in your home.

Chas Roberts is the largest and oldest residential HVAC provider in Arizona and has been in business for over 75 years. Contact us for quality, reliable service.