Service Procedure D01A

Size: px

Start display at page:

Download "Service Procedure D01A"

Martin Mason
5 years ago
Views:

Service Procedure D01A 0Title: RETURN AIR, DISCHARGE AIR, COIL, AND AMBIENT TEMPERATURE SENSOR TEST Where Used: All units equipped with μp-vi Microprocessors and Revision 40xx Software.

1 Service Procedure D01A 0Title: RETURN AIR, DISCHARGE AIR, COIL, AND AMBIENT TEMPERATURE SENSOR TEST Where Used: All units equipped with μp-vi Microprocessors and Revision 40xx Software. Purpose: This procedure must be used to confirm the proper operation of the return air, discharge air, coil and/or ambient sensors. STEP ACTION RESULTS COMMENTS NOTE: Polarity must be considered when connecting temperature sensors. If the sensors are connected backwards, the display will show four dashes (----). Consult the schematic diagram or wiring diagram for the correct connections. 1 Turn the unit off. 2 Disconnect the appropriate sensor at the plug next to the sensor. 3 Turn the unit on. The Standard Display will appear. P41OD01A - 19 July 1999 D01A - Page 1

2 Service Procedure D01A 4 Select the appropriate sensor by pressing the Select key. 5 Using a high quality digital multimeter, check the voltage at the sensor plug on the plug half that is still connected to the microprocessor. 6 If the voltage measured in Step 5 above is incorrect, recheck the voltage at the same circuits on the sensor connector on the back of the microprocessor. 7 If a bad microprocessor is indicated, check with Microprocessor Tester as shown in Service Procedure A01A. 8 If the microprocessor and harness appear to be OK, but the return air or discharge air sensor is still suspected of reading incorrectly, check the sensor grade calibration using Service Procedure A15A and with an ice water bath as shown in. The display for the disconnected sensor should show [----]. The voltage must be from 4.90 to 5.10 volts DC. The voltage must be from 4.90 to 5.10 volts DC. If all sensors show [----] without being disconnected, the microprocessor is probably defective. Test it using Service Procedure A01A. If the voltage is correct, replace the sensor. If the voltage is correct at Step 6 and incorrect at Step 5, the problem is in the wiring. If the voltage is incorrect in both Steps 5 and 6, the problem is in the microprocessor. Substitute or replace sensor if needed. Return air and discharge air sensors must be replaced with graded sensors and calibrated as shown in Service Procedure A15A. Coil and ambient sensors are ungraded sensors and do not require calibration. P41OD01A - 19 July 1999 D01A - Page 2

3 0Title: CHECKING SENSOR CALIBRATION WITH AN ICE WATER BATH Where Used: All units equipped with μp-vi Microprocessors and Revision 40xx Software. Purpose: This procedure must be used when it is necessary to confirm sensor calibration of the return air or discharge air sensors. NOTE: To be effective, an ice water bath must be constructed as shown in this procedure. Using a bag or cup of ice instead of an insulated container and/or failing to stir the bath during the test will result in erroneous readings. STEP ACTION RESULTS COMMENTS NOTE: Polarity must be considered when connecting temperature sensors. If the sensors are connected backwards, the display will show four dashes (----). Consult the schematic diagram or wiring diagram for the correct connections. Preparing the Ice Water Bath 1 Obtain a clean, well insulated container with a capacity of at least one quart. NOTE: To be effective, an ice water bath must be constructed as shown in this procedure. Using a bag or cup of ice instead of an insulated container and/or failing to stir the bath during the test will result in false readings. P41OD02A - 19 July 1997 D02A - Page 1

4 2 Clean the insulated container. NOTE: Contamination of the container with antifreeze or other substances will result in false readings. 3 Completely fill the insulated container with crushed ice. 4 Add cold water to the top of the ice in the insulated container. 5 Allow the container to stabilize for at least 15 minutes. Stir the contents of the container briskly several times during this period. 6 Remove the sensors to be tested as required to immerse them in the ice water bath. The graded return air and discharge air sensors are the only sensors requiring ice water calibration. Testing the Return Air Sensor 7 Be certain the unit display is showing the Standard Display. 8 After the bath has stabilized for 15 minutes, insert the return air sensor completely into the ice and water mixture. Stir the bath briskly. 9 Allow the sensor to remain in the bath for at least 5 minutes. Stir the bath briskly several times. 10 Stir the bath briskly and observe the Standard Display. The display must show setpoint ± 0.4 F (0 C ± 0.2 C). P41OD02A - 19 July 1997 D02A - Page 2

5 11 If the display is not within the required range, recheck the return air sensor calibration as shown in Service Procedure A15A. 12 If the sensor is still not within the required range as shown it must be replaced. Testing the Discharge Air Sensor 13 Be certain the unit display is showing the Standard Display. 14 After the bath has stabilized for 15 minutes, insert the discharge air sensor completely into the ice and water mixture. Stir the bath briskly. 15 Allow the sensor to remain in the bath for at least 5 minutes. Stir the bath briskly several times. 16 Press the Select key to select [DIS.A] and press the Enter key to lock the display. 17 Stir the bath briskly and observe the display. 18 If the display is not within the required range, recheck the discharge air sensor calibration as shown in Service Procedure A15A. The display must show setpoint ± 0.6 F (0 C ± 0.3 C). The display must show [DIS.A] ± 0.6 F (0 C ± 0.3 C). P41OD02A - 19 July 1997 D02A - Page 3

6 19 If the sensor is still not within the required range as shown it must be replaced. Re-install Sensors 20 Re-install sensors in the appropriate locations. Be certain the return and discharge sensors are not interchanged. 21 Secure sensor harnesses and replace any cable ties as required. The display must show [DIS.A] ± 0.6 F (0 C ± 0.3 C). Be certain the return air and discharge air sensors are not interchanged. If they are interchanged the unit will fail the pretrip. P41OD02A - 19 July 1997 D02A - Page 4

7 Service Procedure D03A 0Title: PRESSURE SENSOR TEST Where Used: All μp-vi Microprocessors. Purpose: This procedure can be used to confirm the proper operation of the suction or discharge pressure transducer. STEP ACTION RESULTS COMMENTS 1 Turn the unit on. 2 Select the pressure transducer by pressing the Gauge key to show [SUC.P] or [HED.P]. The display should show the pressure reading for the sensor. If the sensor reading is obviously incorrect or the display shows [----], proceed as shown below. If all sensors show [----] without being disconnected, the microprocessor may be defective, a sensor lead may be shorted to chassis ground. Confirm incorrect reading with refrigeration gauges as necessary. 3 Turn the unit off. 4 Disconnect the suction or discharge pressure transducer at the transducer plug. 5 Turn the unit on. 6 Using a high quality digital multimeter, check the voltage at The voltage between wires HSPP and HSPN must be from If the microprocessor fails the test it must be replaced. the transducer plug on the plug half that is still connected to the microprocessor to 5.10 volts DC. If the voltage is not present, check the microprocessor using Service Procedure A01A. 7 If the microprocessor passes the test, check the continuity of harness wire HSPP, HSPN, DPI and/or SPI from the microprocessor to the sensor using Service Procedure H04A. The wires run from the microprocessor sensor connector J17 to the transducers. See the wiring diagram for details. If the voltage in step 6 checks good and continuity exists to the microprocessor on the HSPP, HSPN, DPI and/or SPI wires, replace the transducer. P41OD03A - 19 January 2000 D03A - Page 1

DigiTemp. Digital Thermometer

DigiTemp. Digital Thermometer DigiTemp R Digital Thermometer (Standard Version) Page 1 The DigiTemp battery-powered digital thermometer is designed to suit a wide range of industrial applications which demand accurate measurement of