Carrier 39L - Manual (Page 108)

Table 22 — Direct Expansion (DX) Cooling Test
KEYBOARD
ENTRY
DISPLAY
RESPONSE
COMMENTS/ACTION
NOTE: Only the configured number of stages are tested and appear on the display.
DX COOL Entering field test DX cooling coil. (Set the HOA switch to AUTO.)
DXS1 X
STG1 TST
The fan starts. If fan has IGVs, the IGVs open to 30%. After an 11-second delay, the 1st stage of DX cooling
is turned ON.
DXS2 X The 1st stage of DX cooling is turned OFF.
STG2 TST After a 2-second delay, the 2nd stage of DX cooling is turned ON.
DXS3 X The 2nd stage of DX cooling is turned OFF.
STG3 TST After a 2-second delay, the 3rd stage of DX cooling is turned ON.
DXS4 X The 3rd stage of DX cooling is turned OFF.
STG4 TST After a 2-second delay, the 4th stage of DX cooling is turned ON
DXS5 X The 4th stage of DX cooling is turned OFF.
STG5 TST After a 2-second delay, the 5th stage of DX cooling is turned ON.
DXS6 X The 5th stage of DX cooling is turned OFF.
STG6 TST After a 2-second delay, the 6th stage of DX cooling is turned ON.
DXS7 X The 6th stage of DX cooling is turned OFF.
STG7 TST After a 2-second delay, the 7th stage of DX cooling is turned ON.
DXS8 X The 7th stage of DX cooling is turned OFF.
STG8 TST After a 2-second delay, the 8th stage of DX cooling is turned ON.
EXIT TST The fan and preceding DX cooling stage shut OFF.
TST CMPL Test is complete. The unit is back under automatic control.
Electronic Valve Actuator Field Test — The elec-
trically operated valve actuators supplied with 1 ⁄
2
-in. to
1 1 ⁄
4
-in. valve assemblies are a hydraulic, linear-piston type.
The actuators supplied with the 1 1 ⁄
2
-in. to 3-in. valve assem-
blies are an electro-mechanical type. Both types of actuators
contain a spring as part of the valve assembly. The spring
returns the stem to its normal position whenever there is a
loss of power or signal. Both actuators contain an internal
solid-state drive which accepts a proportional 4 to 20 mA
signal generated by the controller.
An increase in signal proportionally extends the actuator
shaft and pushes the valve stem down. A decrease in signal
retracts the actuator shaft and lifts the valve stem up. Valve
construction determines normal valve flow, either stem-up
open, or stem-up closed. On 3-way mixing valves, stem-up
allows flow from port B to port AB.
Perform field test for actuator as follows:
1. Verify actuator is powered by 24 vac at the WHITE/
BLUE and BLACK actuator wires.
2. Use a digital milliamp meter to verify the mA signal and
proper polarity at the input signal leads,
ϩRED and
−GREEN. A digital volt meter with a minimum of 2-place
accuracy may be used to determine signal value, see
Table 23.
3. Enter the heating coil valve or cooling coil valve Quick
Test, retract the actuator shaft and completely lift valve
stem.
4. While still in Quick Test, press . The actuator shaft
should extend completely, pushing valve stem down. Exit
Quick Test procedure.
Table 23 — Digital DC Volt Meter vs
DC Milliamp Meter
DC MILLIAMPS DC VOLTAGE
4 .33
8 .57
12 .99
16 1.32
20 1.65
NOTE: The internal solid-state drives of the factory-supplied elec-
tronic actuators impose a 82.5 ohm impedance to the signal current
loop. A proportional voltage, ranging from 0.33 vdc at 4 mA to to 1.65 vdc
at 20 mA will be present.
CONTROL LOOP CHECKOUT
Checkout and adjustment of control loops should only
be performed by certified Carrier Comfort Network tech-
nicians. The following checkout procedure is offered as
a guide and presumes the user has obtained basic knowl-
edge of controls through CCN training.
To Check Operation of Analog Outputs — The
control algorithms of the 39L and 39NX use the master/
submaster loop concept. The master loop monitors the mas-
ter sensor (the sensor which tries to maintain the desired set
point), and calculates the submaster reference required to do
so. The submaster loop monitors the submaster sensor and
controls the output to the controlled device. These algo-
rithms require a number of gain values to function properly.
The 39L and 39NX come with preset default values. How-
ever, it may be necessary to adjust several of these values to
achieve stable control. These values are submaster loop gain
(SMG), submaster loop center value (SCV), master loop pro-
portional gain (MPG) and, in some cases, master loop in-
tegral gain (MIG).
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