CAUTION: Never perform this test while the compressor is running. Turn the chiller off and ensure that the compressor will not start.
1. Check for 24vdc at 1X2-3 vs ground (that feeds the red wire of the optical eye 4B2). If no power found then check the power supply and the wiring. See Image 3 below.
2. Re-check the signal wiring from the sensor to the llid.... White to 1X2-1 to llid 1A8 J2-1. Black to 1X2-2 to llid 1A8 J2-2. See Image 3 below.
3. Remove the snap ring securing the sensor in oil line well, or unscrew the sensor from the well. Remove the sensor from the well. Note: The optical sensor is separated from the refrigerant by a clear prism, therefore, it is not necessary to recover refrigerant when removing the sensor.
5. Place a mirror or white piece of paper over the face of the sensor (holding the white paper several inches away from the sensor helps sometimes), View the status of the input on TU.
6. Place a piece of black electrical tape directly on the face of the sensor (HINT: the black plastic cap that comes on a new oil level sensor SEN00703 also works well for this). After 10 seconds, the status should change. Remove the black plastic and replace it with the white paper again, after 10 seconds the input status should change back.
7. If no state change is seen, then lift one or both wires off of J2-1 or 2 (ie open the input signal to 1A8). View in TU -Binding View - Properties tab. Then use a jumper to short between 1A8 J2-1 and 2. If the state of the input changes vs open or shorted, then the binary input llid is ok and the optical sensor or the wiring to/from it must be at fault.
Notes:
- Earlier versions of the optical sensor had a brass sleeve or collar on the sensor body, see Image 1 below. If the sensor is powered and if you short that sleeve to ground while removing the sensor from the well or while handling it you may damage the sensor. Starting in ~2011 the sensor body is all plastic. See Image 2.
- Do NOT apply 24vdc to the 1A8 llid binary input terminals. If you do you may damage the llid. Test the binary input by simply opening the input or shorting the input with a jumper wire.
- If the sensor harness is equipped with a shield, ensure the shield is terminated at a good chassis ground.
Image1:
Image 2:
SEN00703
Image 3:
Optical Sensor wiring to the 1A8 llid.
Image 4:
Viewing the 1A8 Binary Input status in Binding View - Properties tab.
Original HUB Document: DOC-208143
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.