TROUBLESHOOTING CHART
SYMPTOM POSSIBLE CAUSE CORRECTIVE PROCEDURE
ROOM TOO COLD Thermostat Setting
Incorrect
Check thermostat setting — move thermostat lever slightly
toward red area. If unit shuts off, leave in this (or in an
intermediate) position. See Fig. 40.
Volume Controller
Setting Incorrect
Check actual volume controller setting vs design cfm —
readjust volume controller setting. Minimum flow set above
stop.
Minimum Flow Set
Above Internal Stop
Turn minimum flow star wheel counterclockwise to zero
position.
Supply-Air Temperature
Too Low
Check actual temperature of supply air vs design supply
air temperature. If required, raise supply-air temperature.
Controls Improperly
Seated
Check connections between filter and plenum, volume con-
troller and filter, filter and bellows.
Tubing Loose or Kinked Check interconnecting tubing between units. Refer to
job drawings; check control arrangement — secure as
required.
Plugs and Caps Not
Installed Properly
Check cap on bellows end connection. Check caps and
plugs on filter.
Unit Controlled by More
Than One Set of Controls
Check job drawings for proper control arrangement — make
changes as required.
Filter Clogged Visually check filter media — replace only if excessively
dirty. (Normally, filter will not require replacement.)
Volume Controller
Defective
Check volume controller operation with thermostat lever
set at extreme blue area — replace volume controller
if unit airflow does not decrease when cfm setting is
decreased.
Thermostat
Defective
Check thermostat operation — replace thermostat if tem-
perature at thermostat is below 75 F and airflow does not
shut off when lever is at extreme red area.
Bellows
Defective
Check bellows — remove controls, cap one end of bel-
lows, connect tube to other end and inflate until unit shuts
off. Trap air in bellows. If unit flow increases, bellows is
defective — replace.
Supply Pressures to
Filter Not Correct
Remove controls including filter. Check pressures at end
plug. There must be pressure reading at each connection.
Top connection pressure reading must be higher than low
connection pressure reading. If pressure readings are the
same or opposite of above — move controls to another
unit.
ROOM TOO WARM Thermostat Setting
Incorrect
Check thermostat setting — move thermostat lever slightly
toward blue area. If air is discharged from unit, leave lever
in this (or in an intermediate) position. See Fig. 40.
Volume Controller
Setting Incorrect
Check actual volume controller setting vs design cfm —
readjust volume controller setting.
Supply-Air Temperature
Too High
Check actual temperature of supply air vs design supply
air temperature. If required, reduce supply-air temperature.
Duct Pressure Incorrect Measure duct pressure — verify per Table 6.
Unit Controlled By More
Than One Set of Controls
Check job drawings for proper control arrangement — make
changes as required.
Tubing Loose; Control Caps
Not Installed Properly
Check interconnecting tube between volume controller and
thermostat. Check caps on volume controller at thermo-
stat connection.
Volume Controller
Defective
Check volume controller operation with thermostat lever
set at extreme blue area. Replace volume controller if air-
flow does not increase when volume controller cfm setting
is increased.
Thermostat
Defective
Check thermostat operation — replace thermostat if tem-
perature at thermostat is above 69 F and the cfm is not at
design requirements, although lever is at the extreme blue
area.
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