Issue:
Evaporator Leaving Solution Temperature Sensor Failure (CGAF)
Resolution:
| EVAP LEAVING SOLN TEMP SENSOR FAILURE |
This diagnostic occurs when there is not a valid signal on the evaporator leaving solution temperature sensor input on the Cold Generator Module (CGM, 1U48) at pins J5-1 and J5-2.- The sensor has to be in the range of 55° F to 209° F (approximately 500,000 to 700 ohms).
- All IntelliPak Chiller units ship with an evaporator leaving solution temperature sensor as standard.
- On units with an evaporator barrel, (made before May 2003) this sensor is located on the pipe elbow on the leaving side of the evaporator barrel.
- On units with the brazed plate heat exchanger, (made after May 2003) this sensor is located on the opposite side of the heat exchanger from the water inlet and outlet connections, toward the bottom.
Here are the steps for Intellipak Air-Cooled Chiller
Step #1 Wiring Error
- Verify the wiring between the Evaporator Leaving Solution Temperature Sensor and the Cold Generator Module (CGM, 1U48) J5-1 and J5-2.
- Refer to unit schematics for wire numbers and connections.
- If the wiring checks good, proceed to the next step.
Step #2 Sensor Checkout
- Disconnect the sensor wires from J5 on the CGM (1U48).
- Check the resistance reading of the sensor and wiring at P5-1 and P5-2. Compare the resistance reading to the above chart.
- If the value is not correct, double check for wire errors.
- Replace sensor if none are found.
- If the value is correct, proceed to the next step.
| TEMPERATURE (F) | RESISTANCE (kW) | TEMPERATURE (F) | RESISTANCE (kW) |
| -40 | 346.1 | 71 | 11.60 |
| -30 | 241.7 | 72 | 11.31 |
| -20 | 170.1 | 73 | 11.03 |
| -10 | 121.4 | 74 | 10.76 |
| -5 | 103.0 | 75 | 10.50 |
| 0 | 87.56 | 76 | 10.25 |
| 5 | 74.65 | 77 | 10.00 |
| 10 | 63.80 | 78 | 9.76 |
| 15 | 54.66 | 79 | 6.53 |
| 20 | 46.94 | 80 | 9.30 |
| 25 | 40.40 | 85 | 8.25 |
| 30 | 34.85 | 90 | 7.33 |
| 35 | 30.18 | 100 | 5.82 |
| 40 | 26.22 | 105 | 5.21 |
| 45 | 22.85 | 110 | 4.66 |
| 50 | 19.96 | 120 | 3.76 |
| 55 | 17.47 | 130 | . 3.05 |
| 60 | 15.33 | 140 | 2.50 |
| 65 | 13.49 | 150 | 2.05 |
| 66 | 13.15 | 160 | 1.69 |
| 67 | 12.82 | 170 | 1.40 |
| 68 | 12.50 | 180 | 1.17 |
| 69 | 12.19 | 190 | 0.985 |
| 70 | 11.89 | 200 | 0.830 |
Step #3 CGM Checkout
- Connect a known resistance in the valid range to J5-1 and J5-2 on the CGM (1U48).
- Using the Human Interface (1U65) check the status of the Evaporator Leaving Solution Temperature Sensor Input.
- If the diagnostic clears and the correct temperature is displayed, recheck wiring and sensor.
- If the Human Interface does not display the correct value with the resistor connected to the board, replace the CGM (1U48).
Document Identifier: DOC-73841
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.