TROUBLESHOOTING THE THERMOSTAT
Temperature reading is incorrect, | • Sensor or controller may be bad. | Place a jumper wire across the | |
showing a sensor error, | or | Sensor connections may be bad. | thermocouple input terminals. The |
LOAD LED is switching at the |
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| display should indicate ambient |
wrong temperature. |
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| temperature. If it does, the |
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| controller is ok. If not, replace |
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| controller. |
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| Decrease set point below ambient |
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| temperature, LOAD LED should be |
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| off for heating controllers. If it is, the |
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| controller is OK. |
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| Increase set point above ambient |
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| temperature. LOAD LED should be |
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| on for heating controllers. If it is, the |
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| controller is OK. |
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| • Controller is wired incorrectly. | Verify proper wiring. Call |
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| KEATING for a diagram. |
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Temperature reading is decreasing, | • Thermocouple polarity is reversed. | Check thermocouple connections. | |
but actual temperature is increasing. | Red wire denotes negative wire. | All connections, including extension | |
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| wire, must maintain the correct |
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| polarity. Correct if needed. |
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| • Ambient temperature in the control | Measure temperature in cabinet to |
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| cabinet is over 70°C. | ensure it is below 70°C. |
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| For troubleshooting the thermocouple, use the chart below |
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| Temperature (°F) | Resistance (Ohm) | |||||
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| 25.00 |
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| 95 | 0.30 |
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| 100 | 3.80 |
| 20.00 |
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| 125 | 4.60 |
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| 150 | 5.50 | |
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Ohm) | 15.00 |
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| 175 | 6.40 |
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| 200 | 7.90 | ||
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(Ω |
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| 225 | 8.40 |
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| 250 | 9.70 | |
Resistance |
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10.00 |
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| 275 | 10.90 | |
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| 300 | 12.40 | |
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| 325 | 13.80 |
| 5.00 |
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| 350 | 15.10 |
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| 375 | 17.00 | |
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| 400 | 18.40 |
| 0.00 |
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| 425 | 20.20 |
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| 450 | 21.30 | |
| 95 | 125 | 175 | 225 | 275 | 325 | 375 | 425 | 475 | ||
| 475 | 23.30 | |||||||||
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| Temperature (°F) |
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