White Rodgers IF90-371 Dead Batteries

[tornado503]

I installed this stat over 18 months ago and the customer was happy, without a callback. About two months ago, got a call that she had been having to replace the stat batteries every three weeks since new. The stat is suppose to be power stealing, so the batteries should have lasted for years. I responded and rewired the the stat as powered with the common wite now connected. Result: No CHANGE! Every 3 weaks dead batteries. I called White Rodgers Tech Support and got a woman who suggested that I install two 10 Ohm resistors; one between R-W and R-Y. I ask, "Are You Sure"? 10 Ohms? She said YES! So, as I anticipated, the low value of 10 ohms causes the control module to switch on both Heat and Cooling. So much for technical Support.
Anyone have any other ideas. I have had excellent luck with this stat in the past and find it hard to believe that the stat is at fault. Oh Yes, let me add that the supply voltage to the stat is a solid 28 volts, so low voltage is NOT a problem.

Thanks in Advance....... What am I missing ??? A jumper or setting??

[ISOTHERMAL]

I have a Church with 5 of those same T-stats. One needs the batteries changed at least once a month. I contacted W/R as well. First they asked if the back light was on constantly. It is not. Later they said to replace the T-stat it must be bad. I'm not sure if it ever got replaced or not.