Carrier 69NT40-541-300, Операция и обслуживание, Страница: 112 / 152

6 − 24 T − 318
6.24.3 Sensor Re-Installation
a. Sensors STS/SRS
To properly position a supply sensor, the sensor must be
fully inserted into the probe holder. This positioning will
give the sensor the optimum amount of exposure to the
supply air stream, and will allow the Controller to
operate correctly. Insufficient probe insertion into the
probe holder will result in poor temperature control due
to the lack of air flow over the sensor.
It is also necessary to ensure that the probe tip does not
contact the evaporator back panel. The design
minimum clearance of 6mm (1/4 inch) should be
maintained (see Figure 6-28).
b. Sensor RTS/RRS
Reinstall the return sensor as shown in Figure 6-29. For
proper placement of the return sensor, be sure to
position the seal section of the sensor against the side of
the mounting clamp.
c. Sensor DTS
The DTS sensor must have insulating material placed
completely over the sensor to insure the coil metal
temperature is sensed.
Cap and Grommet
Assembly
Probe
Holder
Supply Sensor
Sensor
Wires
Supply
Air
Stream
Evaporator
Back Panel
6 mm
(1/4 inch)
Figure 6-28 Supply Sensor Positioning
Evaporator Grille
Combination
Sensor (Mount in
Either Clamp)
Mounting
Clamp
Seal
Figure 6-29 Return Sensor Positioning
6.25 VENT POSITION SENSOR (VPS)
The vent position sensor (VPS) determines the position
of the fresh air vent in near real-time via the Cd45.
The fresh air VPS alarm (AL50) will occur if the sensor
reading is not stable for five minutes or if the sensor is
outside of its valid range (shorted or open). This can
occur if the vent is loose or the panel is defective. To
confirm a defective panel, assure that the wing nut is
secure and then power cycle the unit.
The alarm should immediately go inactive. Check the
four-minute stability requirement. If the alarm reoccurs
after the four minutes and the panel was known to have
been stable, then the panel should be replaced.
If the alarm immediately reappears as active, the panel
should be replaced.
Upper VPS:
In order to replace the VPS, the panel must be removed
and replaced with another upper fresh air panel
equipped with VPS.
Upon installation, a new VPS assembly requires
calibration as follows:
1. Rotate the vent to the 0CMH/CFM position.
2. Code select Cd45 will automatically be displayed.
Press the Enter key and hold for five seconds.
3. After the enter key has been pressed, the display will
read CAL (for calibration).
4. Press the ALT MODE key and hold for five seconds.
5. After the calibration has been completed, Cd45 will
display 0 CMH / CFM.
Lower VPS:
1. Remove Condenser fan guard.
2. If unit is equipped with Partlow recorder, remove four
Partlow box assembly mounting bolts and pull Part-
low box assembly away from unit.
If unit is not equipped with Partlow remove left hand
access panel to obtain clearance behind fresh air
make-up assembly.
3. Remove the two nuts and two washers that hold the
slide assembly on. These threads are staked the
nuts will be cutting threads during removal.
4. Remove slide assembly.
5. The VPS bracket may be riveted in place. If that’s the
case, drill out rivet heads.
If bracket is bolted, remove bolts, washers, and nuts.
6. Note position of wire ties and wire routing for new
sensor installation.
7. Remove sensor and bracket assembly from the
backside of fresh air make-up.
8. Insert new sensor assembly through clearance hole
where the old sensor was removed and route wire
harness as noted in step 7.
9. Mount bracket to unit using bolts, washers, and nuts.
10.Wire tie wire harness in locations noted in step 7.
11. Calibrate sensor:
a.Use a multi-meter set to 200k ohms. Connect lead to
VPS connector.
b.Turn the gear wheel on the motor all the way to the
right (clockwise) until it stops.