I added a fresh air damper and control, ( Soler Palau MD6-ES24VK) to my furnace (2006 York GY9S). The damper worked great in the winter but now that I am doing some cooling, I noticed that the outside compressor and fan come on but the inside furnace fan does not come on. Also, the thermostat fan-on setting does not work in hot or cold weather anymore. I have five wires: W, Y, R. G and C. The G wire from the thermostat was removed at the furnace and sent to the damper controller G connection. A separate wire was taken from the furnace G spot to a B connection at the damper control. With a little research I have determined that the furnace fan is automatic with heating but not with cooling.

When I unhooked the damper controller and put everything back as originally installed, it all worked normally again. The furnace fan worked in cooling and the thermostat fan-on control worked.

When I tried to get support from Soler Palau, the person that I talked to had no clue. How can I wire things so that I am able to use the fresh air damper control with cooling? Please help.

  • I take it the furnace fan does not come on when you move the thermostat Fan switch to On with the system Off and the fresh air damper control present? – ThreePhaseEel Mar 31 at 12:14
  • Also, I take it R and C from the furnace are connected to the correct terminals on the damper controller? – ThreePhaseEel Mar 31 at 12:17
  • One more thing: what are you using for a thermostat here? – ThreePhaseEel Mar 31 at 12:21
  • The fan switch does not work when the damper control is present. The R and C were connected to the damper controller as instructed in figure one of installation manual. I am using a Honeywell TH4110D1007 5-2 Programmable Thermostat. Thanks for your interest. – stardc Mar 31 at 16:55

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