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» Support T40-1143SA

Troubleshooting Poor Temperature Regulation
• This page lists problems that may affect the temperature performance of your LUX thermostat with suggested resolutions.
• For more detailed information please refer to the instructions that came with your thermostat.
The instruction manual for this model can be viewed in PDF format by clicking here.
 
Model T40-1143SA
   
Problem Resolution
No fan function in heat mode
  1. Move the yellow wire attached to the "Y" terminal on the sub-base to the "A" terminal.
 
Fan On continuously
  1. Move Fan switch from ON to Auto
  2. Remove the "G" wire from the thermostats wiring terminal. If fan continues to run, then either the system is miswired, or the problem is in the system, not the thermostat.
   
Indicates incorrect room temperature
  1. Remove the cover. Locate circular pointer attachment on rear of cover. Adjust temperature reading by rotating the pointer attachment so that the indicated temperature is correct.
 
Heats or cools more than 5 degrees past its displayed set temperature
  1. If poor performance is in Heat mode, refer to the installation section of the thermostats manual to verify that the units anticipator is set appropriately. Note that it may be adjusted from the recommended setting to accommodate your preferences.
  2. Refer to wiring to verify that it is according to the wiring diagram for your system.
  3. Verify that your units placement and mounting are optimum per the installation section of it's manual.
  4. Calibrate mechanism
 
4a Disconnect electrical power to the thermostat at the furnace, main fuse or breaker box.
4b. Remove thermostat cover.
4c. Locate 1 inch diameter disc with pointer. This is the anticipator disk. Behind it is the units temperature sensing coil. The end protruding from it is the contact arm.
4d. Rotate temperature dial to lowest setting. Listen carefully for a small click while slowly rotating the units dial to higher settings. Note the temperature at which the click is heard.
4e. Listen carefully for a small click while slowly rotating the units dial back to lower settings. Again note the temperature at which the click is heard.
4f. The center point between two clicks should be the at room temperature. Repeat steps 4d and 4e above until you are sure of the center point.
4g. If the center point between two clicks does not indicate room temperature the mechanism may adjusted as follows.
4h. Hold temperature setting lever at room temperature.
4i. Firmly grasp the anticipator disk being careful not to touch the temperature sensing coil.
4j. Rotate the anticipator disk slightly. Clockwise rotation lowers the indicator. Counter clockwise rotation raises the indicator.
4k. Test the new position as in step 3 above. Repeat adjustment and test as necessary.
No heat or cooling when expected.
  1. Verify that the wire connections to your thermostat are clean and tight.
  2. Refer to wiring to verify that it is according to the wiring diagram for your system.
   
Advanced Trouble Shooting
  1. If your system is a low voltage system having 24VAC or less, and you are technically inclined, you may jump terminals as given below out to detect a malfunction in your system.
 

Fan Test

  1. FAN TEST: If your system has a fan, test it first.
  2. If the system is Heat only, or if there is a jumper between the "RH" and "RC" terminal of your thermostat, then with the power ON at the fuse box, touch the "G:" wire to the "RH" terminal. The fan should come on immediately and stay on. The rush of air is usually easily heard.
  3. If the system is Cool only, or if the system is Heat and Cool and there are separate wires to "RH" and "RC", and there is no jumper between them: then with the power ON at the fuse box, touch the "G:" wire to the "RC" terminal. The fan should come on immediately and stay on.
  4. If the fan does not come on it is an indication that there is a problem with your system. Check any breaker o fuses that fed the 24VAC transformer that powers your system
  5. If persists, contact qualified service personnel for aid in determining the fault.
   

Heat Test

  1. To test gas or oil heating systems, take the "W" wire off its terminal. With the power ON at the fuse box, touch the "W:" wire to the "RH" terminal for a couple of minutes and the heater should come on and stay on until the wire is removed.
   

Cooling Test

  1. To test cooling, remove the "G" and "Y" wires. Connect them together to the "RC" terminal for several minutes to observe operation. The system should come on and stay on. If the cooling fails to come on, or comes on and off, the problem is in the system.
 

Heat Pump Test

  1. To test a heat pump system with an "O" wire, three wires must be connected together with the power terminal. The power terminal is "R". "RH" and "RC" with a jumper between them my also be consider to be a single "R" terminal. With the power ON at the fuse box, connect the "O" and "Y" or "Y1" and "G" wires to the "R" terminal for a couple of minutes and the unit should provide cool air. Wait at least 5 minutes and repeat this test without the "O" wire. The unit should provide Heat.
  2. To test a heat pump system with a "B" wire, three wires must be connected together with the power terminal. The power terminal is "R". "RH" and "RC" with a jumper between them my also be consider to be a single "R" terminal. With the power ON at the fuse box, connect the "B" and "Y" or "Y1" and "G" wires to the "R" terminal for a couple of minutes and the unit should provide warm air. Wait at least 5 minutes and repeat this test without the "B" wire. The unit should provide cool air.
   
 
  1. Contact your HVAC service company or our
    Technical Assistance Line if not resolved.
 
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