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MUA-SVP01A-EN • Direct-Fired Indoor and Outdoor Units 41
Diagnostics
4. Do the dampers track with a change in the %OA setpoint? The dampers
utilized on the unit are not linear with respect to airflow and openness, and as
such, the proportion of outside air damper movement will not be exactly
equal to the %OA setpoint. However, at 20% OA the dampers should be
approximately ½" open.
– Yes. Continue.
– No. Check the damper motor and linkage connections. When 24VAC is
powering the damper actuator and the control signal is 0VDC, the outside
air damper should be close to a "rattle tight" position and the return air
damper should be open. If the 24VAC power is removed, the actuator will
draw the outside air damper tightly closed and the return air damper
tightly open. When 24VAC is powering the damper actuator and the
control signal is 10VDC, the outside air damper should be fully open and
the return air damper should be closed.
5. Is there approximately 24VAC at the COM and EXC terminals on the airflow
station pressure transducer?
– Yes. Continue.
– No. Is there 120VAC on the primary side of the low voltage transformer
and 24VAC volt at the transformer secondary?
– Yes. There is an open in the wiring between the transformer and the
transducer. Locate the wiring problem and rectify.
– No. If there is 120VAC on the primary and 0VAC on the secondary,
replace the transformer. If there is 0VAC on the primary, there is an
open in the wiring supplying power to the transformer. Locate the
wiring problem and rectify.
6. Remove both of the plastic tubes from the airflow station pressure transducer
and gently blow into the HIGH side port. Caution: The transducer is extremely
sensitive. Blowing too hard into the sensing tube may damage the
transducer. Is there approximately 5VDC across the COM and OUT terminals
of the pressure transducer?
– Yes. Continue.
– No. The pressure transducer is defective. Replace it.
7. Remove both of the plastic tubes from the airflow station pressure transducer
and gently blow into the HIGH side port. Caution: The transducer is extremely
sensitive. Blowing too hard into the sensing tube may damage the
transducer. Is there approximately 5VDC across the controller input terminals
that are connected to the transducer?
– Yes. There is a problem with the controller. Replace it.
– No. There is an open in the wiring between these pressure transducer and
the AdaptAire controller terminals. Locate and rectify.
SOLUTION:If less outside air is desired
1. Is heat required?