How to Troubleshoot a Dryer That Isn’t Removing Moisture
Moisture in your air lines is one of the fastest ways to ruin tools, contaminate products, clog filters, and create rust throughout your entire system. So when your air dryer isn’t doing its job, everything downstream starts paying the price.
At Industrial Air Services, we help facilities across Nashville, Knoxville, and Chattanooga diagnose dryer issues every day, especially during Tennessee’s high-humidity months. If your dryer isn’t removing moisture like it should, here’s where to start.
1. Check Your Inlet Temperature — It Might Be Too Hot
Most refrigerated dryers are rated assuming a certain inlet air temperature, usually around 100°F. But in a cramped or poorly ventilated compressor room, inlet temperatures can climb far higher.
If the inlet air is too hot:
Moisture won’t condense properly
The dryer’s refrigeration circuit overloads
Dew point rises
Water passes through to your lines
If your compressor room gets hot in the summer, this is often the root cause.
2. Make Sure the Room Has Proper Ventilation
Dryers give off a lot of heat, and if that heat gets trapped, efficiency drops quickly.
Poor ventilation causes:
High discharge temperatures
Dryer overload
Rising dew point
Water in lines during peak demand
A dryer can’t breathe in a sealed closet. Move air through the room or add ducting to remove heat.
3. Inspect the Condensate Drains — They Frequently Fail
Drains are one of the most common reasons a dryer stops working properly.
If drains fail:
Condensate backs up
Moisture bypasses the dryer
Filters become saturated
Rust begins forming in piping
Check for:
Stuck float drains
Timer drains that aren’t cycling
Zero-loss drains clogged with sludge
Oil clogging the discharge line
If moisture is showing up after the dryer, always inspect the drain first.
4. Replace or Inspect Filters Before the Dryer
Pre-filters and after-filters can clog or become saturated, reducing airflow and pushing moisture past the dryer.
Common symptoms:
Pressure drop
Increased load on the compressor
Wet air at end-use points
Filters are cheap. Running wet air through your system is not.
5. Make Sure Your Dryer Is Sized for Tennessee’s Humidity
Dryers are not all the same, and many are undersized for real-world conditions — especially here in the Southeast.
Humidity increases the amount of water that needs to be removed. An undersized dryer will:
Keep up in winter
Struggle in spring
Completely fail in summer
If your dryer works fine half the year and struggles the other half, sizing is the problem.
6. Refrigerated Dryers: Check the Refrigeration Circuit
A refrigerated dryer depends on a healthy refrigeration cycle.
Issues here can drastically reduce performance.
Watch for:
Dirty condenser coils
Low refrigerant
Failed fans
Frozen heat exchangers
Overheating compressors
If the dryer is running but not cooling, this is a likely cause.
7. Desiccant Dryers: Check the Desiccant Condition
For desiccant dryers, the drying media is everything.
Signs your desiccant is spent:
Loss of dew point
Excessive moisture downstream
Pressure drop through the towers
Dusting or channeling
Oil contamination inside the towers
If your desiccant is oil-soaked, the dryer cannot be salvaged without a media replacement.
8. Look for Piping Issues Feeding the Dryer
Mistakes in piping design can ruin dryer performance.
Problems include:
No wet tank before the dryer
Undersized piping
No drop legs to catch moisture
Long horizontal runs that hold condensate
Improper slope
The dryer should never be the first thing the air hits — a wet tank must come first.
9. Verify Dew Point Readings
Many dryers have onboard dew point indicators. If dew point is higher than normal, something is wrong.
Normal dew point ranges:
Refrigerated dryer: 35–50°F
Desiccant dryer: -40°F or lower
A rising dew point is your early warning sign.
10. Consider Age and Condition — Some Dryers Don’t Fail, They Just Wear Out
Dryers have a lifespan.
After years of heavy use:
Coils corrode
Valves wear out
Desiccant loses capacity
Sensors drift
Controls fail
If your dryer is older and constantly struggling, repairs may cost more than upgrading to a new unit.
A Moisture Problem Never Fixes Itself — but It’s Almost Always Fixable
If your dryer isn’t removing moisture, the key is to diagnose the root cause quickly before rust and contamination spread throughout your air system.
We troubleshoot dryer issues every day and can pinpoint the cause — whether it's ventilation, drains, filters, or sizing.
Industrial Air Services proudly serves Nashville, Knoxville, and Chattanooga, providing dryer repair, moisture control solutions, proper sizing, and complete compressed air system service.
📍 138 Bain Drive • LaVergne, TN 37086
📞 (615) 641-3100
🌐 www.industrialairservice.com
