Service manual

THE SMART SOLUTION FOR ENERGY EFFICIENCY
Vertical DOAS
Rev.: 01/31/13
33
climatemaster.com
Troubleshooting
Supply Blower Will Not Run
Possible Cause Remedy
“Occupied switch in open position Close “Occupied” switch
Loss of main power
Check for tripped circuit breaker
or blown fuse
Blower overload has tripped Correct cause and reset overload
Faulty control wiring
Check for loose or incorrect wires
on system and controller
Compressor Will Not Run
Note: When there is a demand for outdoor air (the
“occupied” switch is on) and the outdoor air does not
need mechanical dehumidifi cation, the compressor and
the refrigeration circuit of the unit will be locked out.
Possible Cause Remedy
Loss of main power
Check for tripped circuit breaker
or blown fuses
Blower overload has tripped Correct cause and reset overload
Faulty wiring
Check for loose or faulty wiring
on system and controller
Compressor overload has tripped Correct cause and reset overload
Compressor failure may have
occurred if:
A: Compressor draws locked
rotor amps
B: Compressor starts but does
not pump
C: Motor windings have shorted
A: Replace compressor (or check
fuses on three-phase units)
B: Replace compressor
C: Replace compressor
Compressor delay-timer Wait 3 minutes for timer
Evaporator Coil Ices Up: Suction Pressure Below 85
psig (HFC-410A)
Possible Cause Remedy
Faulty or improperly set hot-gas
bypass valve
1: Set hot-gas valve to maintain
30°F suction (55 psig)
2: Replace if defective
Insuffi cient evaporator air
fl ow rate
Assure air coil is clean and belts
are tight
Lack of refrigerant Reevaluate system charge
Restricted refrigerant fi lter-drier
Evaluate fi lter pressure drop and
replace if necessary
Defective expansion valve
Evaluate expansion valve
performance and replace if
necessary
Restriction in refrigeration piping
1: Check coil for kinks in tubing
2: Check for debris in distributor
Liquid Line Solenoid
1: Check for 24 volts at the coil
2: Check to make sure solenoid
is tightly secured to the stem of
the valve
Head Pressure is Too High: Above 500 psig (HFC-410A)
Possible Cause Remedy
Lack of adequate water fl ow
Install fl ow meter or circuit setter
to ensure correct fl ow rate
Excessive incoming water
temperature
If water temperature is above
90°F, consult factory for required
fl ow rates
Excessive air in condenser
water lines
Purge lines thoroughly or
install an air eliminator in the
system piping
A: Overload tripped (3-phase only)
B: Contactor faulty
C: Blower cycling on internal
overload (single phase only)
A: Reduce blower speed and
reset overlaod
B: Replace contactor
C: Reduce blower speed
Service valves closed or not
fully open
Fully open service valves
Non-condensables in
refrigeration system
Short-Term: Bleed non-
condensables from high-point
purge points in system
Long-Term: Properly evacuate
and recharge refrigeration system
 CAUTION! 
CAUTION! Do not restart units without inspection and
remedy of faulting condition. Equipment damage may occur.