Tekmar D540, Installation & Operation Manual

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5 of 24 © 2010 D 540 - 08/10
Testing the Thermostat Wiring
Testing the Power
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1. Remove the front cover from the thermostat.
2. Use an electrical test meter to measure (ac) voltage between the R and C
terminals. The reading should be 24 V (ac) +/– 10%.
3. Install the front cover.
Testing the Heat, Cool, and Fan Relays
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1. Remove the front cover from the thermostat.
2. Press Mode button until Mode is set to OFF.
3. Set the electrical test meter to continuity.
4. Place probes between R (3) and W (4), then between Rc (5) and Y (6). In both
cases there should be no continuity. If there is continuity then there may be a
wiring fault or the relay may be faulty.
5. Press Mode button until Mode is set to HEAT.
6. Press the
button and set the heating temperature above the current room
temperature. Make sure the display does not show “WWSD”. The “H1” symbol
should appear on the display.
7. There should be continuity between the R (3) and W (4) terminals.
8. Press Mode button until Mode is set to COOL.
9. Press the
button and set the cooling temperature below the current room
temperature. The “C1” symbol should appear on the display.
10. There should be continuity between the Rc (5) and Y (6) terminals.
11. Press Fan button to set the fan to Auto.
12. Ensure the fan symbol is not shown on the display.
13. There should be no continuity between Rc (5) and G (7) terminals.
14. Press Fan button to set the fan to On.
15. The “Fan” symbol should appear on the display.
16. There should be continuity between the Rc (5) and G (7) terminals.