Economizer Trouble Shooting; To 10 Vdc Motors; Motors Wired To R, B, And W Terminals; Economizer Not Opening - EngA C-TRAC2 Installation, Operation And Maintenance Manual

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Economizer Trouble Shooting

0 to 10 VDC Motors

Check the voltage at the ED and B terminals when the C-TRAC2.1 is in the economizer mode. Zero
volts are closed to minimum position, 10 VDC is fully open and any voltage in between is in the
modulating range. If the dampers stay in the full fresh air position with 10 VDC on them all of the time,
check the minimum position pot setting. There is no shunt resistor required for multiple motors.
If the economizer is not opening refer to the section a few inches below about this topic.

Motors wired to R, B, and W terminals

There is a maximum of three damper motors allowed to be connected to the damper output terminals
"R, B", and "W". A shunt resistor must be placed across terminals "R" and "B" of the C-TRAC2.1 when
more than one damper motor is used (2 motors 1500 ohms resistance, 3 motors 909 ohms).
NOTE:
When multiple damper motors are connected to the same circuit they must
maintain polarity on all connections on the 24 VAC side and DC neutrals.
Note comments in overheating section above re operating as a discharge only control before proceeding.
Ensure the damper motor pot and cam switch are configured to the same setting. The C-TRAC2.1 will
control best if these are set for the motor to stroke to the full 160-degree stroke.
IMPORTANT
SWITCH 7 "ON" forces economizer to minimum when compressor starts, SWITCH 6 "ON" forces it to
minimum when the enthalpy/ODT makes terminal E go high (24 VAC applied to it).

Economizer Not Opening

Is the economizer locked out because the high ambient terminal E has 24 VAC on it? When terminal "E"
has 24 VAC on it the dampers go to minimum position if the damper configuration dipswitch is on.
Is the C-TRAC2.1 in the economizer mode?
If it is, both the heat and cool lights will usually be off (depending on dipswitch configuration). The economizer
operates with the cool light on if the dipswitches 6 and 7 are set "off". Forcing C-TRAC2.1 into economizer
mode, de-energize the C-TRAC2.1 and replace discharge sensor with 1000-ohm resistor. Adjust the
amount of call using set-point dial. Reenergize C-TRAC2 and after a delay up to 10 minutes while internal
timers go from heat to economizer the DC voltage across R and B should go from 2.8 (closed) to about 1.8
volts DC as the economizer opens. Volts also changes 0 to 10 VDC on terminals ED and B.
On units equipped with motors attached to the "R, B", and "W" terminals, if the mechanical cooling starts before the
economizer moves (based on the DC voltage measured at terminals "R" and "B") and you wish to verify if the damper motor
will stroke, disconnect the damper motor wires "R, B", and "W", then jumper the motor terminals "R" and "B". If the
motor does not drive and there is 24 AC volts applied to terminals T1 and T2 then the motor is faulty.
NOTE:
If dipswitch 6 is "on" and terminal "E" is hot, the dampers will not open.
If there is a damper motor connected to the C-TRAC2.1 terminals "R, B" and "W", the voltage at C-
TRAC2.1 terminals "R" and "B" will be:
Fully closed with min. pos. pot at 0
Fully open dampers
If there is no motor connected to the C-TRAC2.1 the voltage at terminals R and B is:
Fully closed with min. pos. pot at 0
Fully open dampers
Is the economizer properly configured? See the information in the economizer
section.
Page v
C-TRAC2.1 MANUAL
= approx. 2.8 VDC
= approx. 1.8 VDC
= approx. 0 VDC
= approx. 1.24 VDC
March 1999 R1