Home › Common Problems › High Humidity Inside the Home
High Humidity Inside the Home
in Richardson, TX
Richardson gets humid air pushing up from the Gulf of Mexico throughout spring and early summer, and on some days the outdoor humidity sits above 80 percent for weeks straight. Your AC is supposed to remove that moisture from the air as it cools the house. When it doesn't, the house feels wet and uncomfortable even at a reasonable temperature, and mold can start growing inside the walls and on window frames.
Quick Answer
When indoor humidity stays high despite the AC running, the system usually isn't running long enough to pull moisture out of the air. This can come from an oversized unit, a refrigerant problem, or leaky ductwork pulling in humid attic air. Richardson's humidity regularly hits 80 percent or higher in spring, and an AC that can't handle that makes the house feel miserable. Call (361) 202-9465 to find out what's driving it.
Telltale Signs
Warning Signs to Watch For
- The thermostat reads 74 but the house feels sticky and hot
- Condensation appears on window glass or window frames on the inside
- Mold spots appear on bathroom ceilings or in closets near exterior walls
- A musty smell lingers in certain rooms even with the AC running
- Indoor humidity gauge reads above 60 percent consistently
Root Causes
What Causes High Humidity Inside the Home?
Short Run Cycles from Oversized Unit
An oversized unit drops the air temperature fast but shuts off before it's run long enough to pull significant moisture out of the air. Humidity removal happens during the full run cycle, not just the first few minutes. Many homes in the Prestonwood area of Richardson were fitted with oversized replacement units in the 2000s, and those systems have never been able to manage humidity well as a result.
The Fix
Unit Sizing Correction
Proper humidity control requires a unit that runs in longer cycles, which means the right-sized equipment for the house. A full load calculation shows what size is actually needed.
Leaky Ductwork Pulling in Attic Air
Attic air in Richardson can reach 140 degrees or more in July, and it holds enormous amounts of moisture. If the return ducts in the attic have gaps or separated joints, the air handler pulls that hot, humid attic air directly into the house rather than pulling from the living space. Even a small gap in the return duct can overwhelm the AC's ability to dehumidify the space.
The Fix
Duct Sealing
A technician inspects the ductwork in the attic for gaps and seals them with mastic or foil tape. Sealing the return side of the duct system can make a noticeable difference in indoor humidity levels within a day.
Low Refrigerant Reducing Dehumidification
Dehumidification happens at the evaporator coil when warm air contacts the cold coil surface and moisture condenses out. When refrigerant is low, the coil doesn't get cold enough to pull much moisture from the air, so humidity stays high even if the temperature drops slightly. This problem gets worse during the 10 to 15 inches of rain Richardson typically gets in May and June, when outdoor humidity is already pushing into the house.
The Fix
Refrigerant Leak Repair and Recharge
Fixing the leak and restoring the proper refrigerant charge lets the coil get cold enough to condense moisture effectively. Humidity levels usually improve noticeably within a day of correcting the refrigerant charge.
Self-Diagnosis
Which Cause Applies to You?
Check the signs you're observing to narrow down the likely root cause before your inspection.
| What You're Seeing | Short Run Cycles from Oversized Unit | Leaky Ductwork Pulling in Attic Air | Low Refrigerant Reducing Dehumidification |
|---|---|---|---|
| Humidity stays high even though the AC seems to reach the temperature setpoint | |||
| Humidity is worse in rooms directly below the attic | |||
| Humidity problem started and worsened gradually over one summer | |||
| AC runs in short frequent cycles and the air feels thick | |||
| Musty smell strongest near supply vents | |||
| Condensation on windows that wasn't there in past summers |
Free Inspection
Get a Diagnosis in Richardson
An on-site inspection is the only way to confirm which cause applies to your property. Free, no obligation.
(361) 202-9465Free on-site inspection
Written estimate before work starts
Serving Richardson & surrounding areas
Other Problems
Services That Fix This
Also Helpful