Table 18 Ð Durablade Economizer Troubleshooting
| PROBLEM | CAUSE |
| REMEDY |
Damper does not | Indoor (evaporator) fan is off. | 1. | Check to ensure that 24 vac is present at terminal C1 on the IFC or | |
open. |
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| that 24 vac is present at the IFO terminal. Check whether 24 vac is | |
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| present at |
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| not present, check wiring (see unit label diagram). |
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| 2. | Check proper thermostat connection to G on the connection board. |
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| No power to economizer motor. | 1. | Check that SW3 is properly making contact with the damper |
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| blade. Check that SW1 is in the NC (normally closed) position. |
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| 2. | Check diode D1. If diode is not functioning properly, replace D1. |
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| 3. | Con®rm that the economizer control board is grounded properly at |
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| |
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| board (brown wire). The economizer motor must also be grounded |
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| properly at the negative motor terminal (brown wire). |
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| 4. | Verify SW1 and SW3 are working and wired properly (see unit label |
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| diagram). |
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| 5. | Check for 24 vac input at both |
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| wire). If 24 vac not present, check unit wiring (see unit label dia- |
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| gram). If 24 vac is found in both places, check for 24 vac at the yel- |
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| low terminal of the economizer control board (yellow wire). If |
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| 24 vac power is not present, replace the economizer control board. |
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| Economizer motor failure. | If the indoor (evaporator) fan and economizer motor are energized, | |
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| verify that there is a minimum of 18 vdc at the positive motor terminal. | |
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| If the motor is not operating, replace the motor. | |
Economizer operation | OAT or EC set too high. | 1. | Set at correct temperature (3 F below indoor space temperature). | |
limited to minimum |
| 2. | Check OAT or EC by setting above outdoor temperature or humidity | |
position. |
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| level. If the OAT or EC switches do not close, replace OAT or EC. | |
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| Verify economizer control board is correctly wired | 1. | Perform the following tests when OAT or EC is closed, Y1 is called |
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| and works properly. |
| for and damper is at minimum position. Con®rm 24 vac on gray ter- |
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| minal of the economizer control board (gray wire). If 24 vac is not |
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| present, check wiring (see unit label diagram). |
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| 2. | Verify that SW1 and SW3 are wired correctly and working properly |
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| (see unit label diagram). |
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| 3. | Check to ensure that 24 vac exists at |
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| 24 vac is not present, check wiring (see unit wiring label diagram). |
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| 4. | Check 24 vac output at |
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| present, replace economizer control board. |
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| Check SAT. | 1. | After verifying that the OAT and EC settings and the economizer |
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| control board wiring are correct, check to ensure that the 24 vac |
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| terminal of the SAT has 24 vac (white wire). If OAT, EC, and control |
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| board are functioning and wired properly and no 24 vac exists, |
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| check wiring (see unit label diagram). |
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| 2. | If |
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| found at terminal T2 on the SAT (pink wire). If 24 vac is not present, |
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| replace SAT. |
Damper does not | Incorrect wiring of economizer. | 1. | Verify that SW2 and SW4 are wired and working properly (see unit | |
close. |
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| label diagram). | |
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| 2. | Check diode D2. If diode is not functioning properly, replace D2. |
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| Verify economizer control board is functioning | 1. | After verifying that the wiring is correct, modulate the damper to the |
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| properly. |
| minimum position. Remove the call for G (evaporator fan). |
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| 2. | If the damper does not move, check for 24 vac at |
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| If 24 vac is not present, check wiring (see unit label diagram). |
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| 3. | If damper still does not move, check for 24 vac at blue terminal of |
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| economizer control board (blue wire). If 24 vac is not present, re- |
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| place the economizer circuit board. |
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| Check SAT. | 1. | After verifying that the wiring is correct and the economizer control |
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| board is functioning properly, place the OAT or EC switch in the |
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| closed position. Place a call for Y1 and open the damper to the fully |
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| open position. Con®rm that the 24 vac terminal of the SAT has |
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| 24 vac (white wire). If 24 vac is not present, check wiring (see unit |
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| label diagram). |
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| 2. | If |
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| at terminal T1 on the SAT (violet wire). If 24 vac not found, replace |
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| SAT. |
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| Economizer motor failure. | If economizer control board and SAT are functioning properly, verify | |
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| that there is a minimum of 18 vdc at the positive motor terminal. If a | |
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| minimum if 18 vdc is present and the motor is still not operating, re- | |
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| place the motor. | |
Economizer damper | Verify that | 1. | Check voltage potential across batteries. If lower than 14 vdc, re- | |
does not close on | control board are functioning properly. |
| place | |
power loss. |
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| recommended that you check this emergency power supply on a | |
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| regular basis or whenever the ®lters are changed. |
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| 2. | If the |
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| tioning properly, check for 14 vdc or higher at the blue terminal of |
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| the economizer control board (blue wire) when power is discon- |
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| nected from unit. If 14 vdc is not present, replace the control board. |
| LEGEND |
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C1 | Ð Common Power |
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EC | Ð Enthalpy Control |
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IFC | Ð Indoor (Evaporator) Fan Contactor |
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IFO | Ð Indoor (Evaporator) Fan On |
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OAT | Ð |
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PL | Ð Plug |
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SAT | Ð |
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SW | Ð Economizer Position Switch |
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