I have a Goodman GMP075-3 REV B I am having a few problems with. First off I just replaced the thermostat because the thermometer was broken in the old CHT18-60. I replaced it with a LUX TX9000TS series.

The problem I was having is if I put the heat on 70 it would only get to about 65. Now I thought this was because of the broken therm. Now with the new LUX in place, I tested everything A/C comes on, fan works etc. If I set the temp at 72 it seems to never get over 65. If I turn it all the way say to 85 I get heat and the house begins to warm up.


I can hear the unit starting, it sounds like the gas is only staying on for about 10 sec and then the blower fan kicks in and the gas burner shuts off. it cycles like this about every 2-3 min, but the blower never shuts off.

When I have it turned up to 85 the burner stays on a lot longer. Is there something else to adjust on the therm? I have had the board replaced once on this unit, I have also had the temp sensor replaced about 3 years ago.

Would appreciate any input thanks.

Check the installation instructions for the new t-stat. There may be additional setup options beyond just the wiring and mounting. Also, in the event this is a 2-stage heat thermostat, make sure you have made the heating circuit connection at W1 as opposed to W2.