5050 Quorum Dr Suite 700, Dallas, TX 75254 
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Start With the Obvious Checks
Open all supply vents. This is the most common cause of uneven temperatures we find, and it’s counterintuitive: closing vents in unused rooms seems logical, but HVAC systems are designed for the full duct system to be open. Closing vents increases static pressure, reduces airflow through the system, and can cause the air handler to work harder — creating more uneven distribution, not less. As a rule, keep at least 80% of your supply vents fully open.
Check for blocked returns. Return air grilles need clear airflow to the air handler. Furniture pushed against a return grille, or rugs over floor returns, restrict the system’s ability to draw air back from the house.
Check the filter. A severely clogged filter restricts airflow throughout the entire system — rooms at the end of long duct runs suffer first, since they depend on adequate pressure throughout the whole system.
What’s Normal
Some temperature variation is expected and doesn’t indicate a problem:
- A 2–4 degree difference between rooms is normal
- Upstairs being 2–3 degrees warmer than downstairs in a two-story home is normal — heat rises
- Rooms over garages being 3–4 degrees cooler is normal due to insulation differences
- Rooms with large windows facing west being warmer in afternoon is normal
More than 5 degrees of consistent difference between similar rooms on the same floor is worth investigating.
Ductwork Problems
DFW homes built in the 1980s through 2000s frequently have attic ductwork that has developed leaks or disconnections over time. Rapid construction during those decades also resulted in some homes with undersized duct runs to rooms at the far end of the system.
Disconnected duct sections send conditioned air into the attic instead of the room. You’ll notice a room that barely receives airflow regardless of how the rest of the house is performing.
Leaky duct joints can lose 20–30% of conditioned air before it reaches the intended room. Rooms at the end of long duct runs suffer most. Duct sealing costs $300–$700 and can meaningfully improve both comfort and efficiency.
Crushed or kinked flex duct is common in attics where items have been stored on top of flexible duct runs. The restriction cuts airflow to entire sections of the house. This is visually diagnosable during an attic inspection.
System Balancing
Airflow to different rooms can be adjusted through balancing dampers in the duct system. Signs that balancing is the issue: some rooms are always too warm while others are always cold, the problem existed since the system was installed, and there are no obvious vent or duct problems. Professional balancing service costs $150–$500 and involves measuring airflow at each vent and adjusting dampers throughout the system.
Oversized Equipment
An oversized system is particularly relevant in Dallas because of how common it is in newer DFW construction. Builders sometimes install larger systems to avoid warranty callbacks during extreme weather, but oversized equipment short-cycles — it reaches setpoint quickly, shuts off, and restarts frequently without ever running long enough to distribute air evenly or manage humidity.
If uneven temperatures have existed since the system was installed, and the house heats or cools unusually quickly to setpoint, sizing may be the underlying issue. A load calculation confirms this.
