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Troubleshooting
CAH-SVX01A-EN 57
Table 5. Air handler troubleshooting recommendations
Symptom Probable Cause Recommended Action
Short belt life Worn sheaves Replace sheaves.
Misaligned belt Realign drive with MVP sheave set at mean pitch diameter.
Grease or oil on belts Check for leaky bearings. Clean belts and sheaves.
Belt slipping Improper belt tension. Adjust tension.
Belts rubbing Remove obstruction or realign drive for clearance.
Bearing noise Poor alignment Loosen bearing set screws and realign (see the “Bearing Set Screw
Alignment” section on page 50).
Failed bearing Replace bearing.
Inadequate lubrication Replace bearing.
Low water coil
capacity
Incorrect airflow Check fan operating condition.
Incorrect water flow Inspect the water pumps and valves for proper operation and check
the lines for obstructions.
Incorrect water temperature Adjust the chiller or boiler to provide the proper water
temperature.
Coil is piped incorrectly Verify coil piping (see the “Coil Piping and Connections” section on
page 28.
Dirty fin surface Clean the fin surface (see the “Coils” section on page 52).
Incorrect glycol mixture Verify glycol mixture and adjust if necessary.
Low refrigerant coil
capacity
Incorrect airflow Check fan operating condition.
Expansion valve is not operating properly or is
sized incorrectly
Check sensing bulb temperature.
Verify valve operation.
Verify proper valve size.
Incorrect refrigerant charge Verify refrigerant charge and adjust if necessary.
Condensing unit failure Verify condensing unit operation.
Coil is piped incorrectly Verify coil piping (see the “Coil Piping and Connections” section on
page 28).
Clogged refrigerant line filter Change filter core.
Failure of suction/liquid line components Verify component operation
Dirty fin surface Clean the fin surface (see the “Coils” section on page 52).
Note: Do not use steam to clean refrigerant coils.
Fin frosting Verify defrost cycle operation.
Verify frostat operation.
Verify refrigerant charge.
Low steam coil
capacity
Incorrect airflow Check fan operating condition.
Coil is piped incorrectly Verify coil piping (see the “Coil Piping and Connections” section on
page 28).
Incorrect steam pressure Verify steam pressure and adjust if necessary.
Excessive steam superheat Check steam superheat.
Steam superheat should not exceed 50ºF.
Failure of steam line/condensate return
components
Verify component operation
Boiler failure Verify boiler operation
Dirty fin surface Clean the fin surface (see the “Coils” section on page 52).
Drain pan is
overflowing
Plugged Drain Line Clean drain line
Unit not level Level unit
Improper trap design Design trap per unit installation instructions
Standing water in
drain pan
Improper trap design Design trap per unit installation instructions
Unit not level Level unit
Plugged Drain Line Clean drain line
Wet interior
insulation
Coil face velocity too high Reduce fan speed
Improper trap design Design trap per unit installation instructions
Drain pan leaks/overflows Repair leaks
Condensation on surfaces Insulate surfaces
Excess dirt in unit Missing filters Replace filters
Filter bypass Reduce filter bypass by ensuring all blockoffs are in place.
Microbial growth
(mold) inside air
handler
Standing water in drain pan See “Standing water in drain pan”