Carrier 69NT40-561-300, Руководство по эксплуатации и обслуживанию

Страница: 157 / 174

7–41 T-365
7.27 EAUTOFRESH SERVICE
7.27.1 Servicing the eAutoFresh Air Filter
Removing the Air Sample Filter Element
The air sample filter element can be accessed in two ways:
• Through the eAutoFresh side evaporator access panel.
• Through the inside of the container by lowering the upper evaporator panel.
1. By hand, unscrew and remove the filter cup from the bottom of the air sample filter assembly.
2. Remove the filter element from the filter assembly.
3. Install the new air sample filter element by reversing the above steps.
7.27.2 Checking eAutoFresh Drive System
Checking the Auto Slide:
To check with an ohmmeter
Disconnect the four pin connector to the stepper motor. With a reliable digital ohmmeter, check the winding
resistance. In normal ambient, the motor should have 72 to 84 ohms measured on the red/green (a-b terminals)
and on the white/black (c-d terminals) leads. If an infinite or zero reading occurs, check connections or replace
the motor. If near normal or normal reading occurs, proceed to the following sections to check out the controller.
To check with a SMA-12 portable stepper drive tester.
The SMA-12 portable stepper drive tester (Carrier Transicold P/N 07-00375-00) is a battery operated stepper
drive which will open and close the auto slide, which allows a more thorough check of the motor.
Checking the Slide Motor:
1. Turn unit OFF.
2. Disconnect the four pin connector from the Stepper Drive to the Stepper Motor, (see Figure 7.28 ).
3. Attach the SMA-12 portable stepper drive tester to the Stepper Motor.
Figure 7.28 Stepper Components
4. Set the SMA-12 pulse per second (PPS) to one PPS and press button to open or close the valve. Each
LED should light sequentially until all four are lit. If an LED fails to light, it indicates an open on that leg
caused by a poor connection or an open coil. Repair or replace as required to achieve proper operation.
5. Set the SMA-12 step rate to 200 PPS. Press open or close while watching the slide mechanism for
movement, this is an indication that the motor is working.
6. If the slide moves using the SMA-12, but fails to move when connected in the unit (refer to “Checking the
Drive Module” in the section that follows.)
Stepper Drive (SD) Stepper Motor (AF)