Page 8 – Van Air Systems MHL3-MHL50 User Manual
Page 8
Van Air Systems MHL-Series Desiccant Air Dryer Operations and Maintenance Manual
Page 8
SECTION 7 TROUBLESHOOTING GUIDE
A
POSSIBLE CAUSE
CHECK
CORRECTIVE ACTION
A1
No power to unit.
Power supply.
Correct power problem.
A2
High inlet air temperature.
The inlet air temperature should not exceed 100°F.
Reduce inlet air temperature to proper level.
An aftercooler may need to be installed after
compressor.
A3
Air flow through dryer in
excess of rated capacity.
Make sure inlet flow to dryer (compressor output, or if installed at
point-of-use, total of air usage downstream of dryer plus purge flow)
does not exceed inlet flow rating of dryer.
Reduce air usage downstream.
A4
Low inlet pressure.
The inlet air pressure should be 100 psig.
Increase inlet pressure or call factory to
resize dryer for actual inlet conditions.
A5
Dirty or obstructed inlet
air filter.
Check inlet airline filter elements.
Replace.
A6
Purge orifice plugged.
Remove and inspect purge orifice.
Clean orifice hole of debris. Use air gun to
clean.
A7
Solenoid coil burned out.
Check magnetic field from coil operation. Place iron or steel
material (a screwdriver works well) at top of coil to feel the
effect when coil should be energized. (Note: see Section 1, for
timing cycle for your unit.)
Replace.
A8
Oil contamination of
desiccant beds.
Verify coalescing inlet filtration is adequate and functioning
properly.
Towers must be replaced if contamination is
suspected.
A9
Timer not operating
properly.
Verify correct timing cycle by observing tower indicator lights on
front panel. (Note: see Section 1, for timing cycle for your unit.)
Replace timer if defective.
A10
Purge flow restricted.
Check mufflers (or purge piping if installed) for excessive back-
pressure. Note: unit is originally supplied with "no-clog" mufflers.
If purge air is piped away from unit,
oversized piping should be used and length
of run should be as short as possible.
B
POSSIBLE CAUSE
CHECK
CORRECTIVE ACTION
B1
Improper operating
conditions.
See A2, A3, A4 above.
B2
Dirty or obstructed inlet
air filter.
See A5 above.
B3
Plugged air passages.
Check inlet and outlet air passages and piping for blockages.
Clear restrictions.
C
POSSIBLE CAUSE
CHECK
CORRECTIVE ACTION
C1
Inlet or outlet shuttle not
shifting.
See A3, A4, A5, A6 above.
C2
Inlet or outlet shuttle not
shifting.
Check for damage or contamination of inlet and outlet shuttles.
Clean or replace as necessary.
C3
Purge orifice plugged.
See A6 above.
C4
Timer not operating
properly.
See A9 above.
C5
Timer not operating
properly.
Incoming power may not be "clean". Fluctuations in voltage can
occur in power circuits shared by devices such as electric motors
and welding equipment.
Supply line voltage from another source.
C6
Dirty or obstructed inlet
air filter.
See A5 above.
C7
Leakage.
With dryer pressurized, remove power from dryer. Check purge
ports on dryer and air system connections for large leaks.
Repair as necessary.
PROBLEM: AIR DRYER DELIVERS WET AIR
PROBLEM: RESTRICTED FLOW THROUGH UNIT
PROBLEM: EXCESSIVE PURGE / BLOWDOWN