I appriciate all of your input. I think you guys have brought up some interesting points. This controller is for an air conditioning unit. It is wired to the HVAC unit and seems to also interface with the compressor outdoors.
I too would like to be able to condition an external signal to solve this problem, but I believe the thermostat is built-in to the device itself so it could not be conditioned from the outside directly. If any of you have any other ideas for interfacing a device to provide some sort of beneficial external control of this unit that would be great.
I have checked out the FAQ and installers/operaters manuals. They are very brief to say the least.
Although I have not studied this board in great detail, it seems somewhat obvious to me how it must work - it reminds me a lot of microprocessor class. But indeed, I do not know the internal wirings and workings of this board and would prefer not to mess with it.
Maybe the best solution is to find another thermostat - but it just seemed somewhat interesting to mess with this one. But, here in the south it would stink to mess it up and be without air for a few days!
The company who designed this has some great energy saving ideas - including limits on what you can set the temperature at (this one is set up for a range of only 10 degrees). Unfortunatly they are not so suitable for this particular installation.
I did try to see if I could adjust the position of VR2 - it seems very much stuck where it is. I did not want to try to pursuade it to move too much and was afriad there may be other unwanted effects to adjusting that. (You should check out Iskra's website - interesting devices.)
If I could have modified this board before it was built, I would have considered putting in a small pot so that the current through RT1 could be modified. Although, this may require a few more devices since the current through the RT1 may be very small (my guess is its a leakage current). It may not be worth the extra expense to the company, but since some of the diodes have tolerances in manufacturing that might make it less accurate, it would be awesome from the consumer side to have a 'qualified technician' be adjust it through a pot. I suspect it may need an a very small amp (op amp or FET) to raise the current to a point where it could be adjusted practically through a pot.
Also, to address the temperature variance within rooms. I have tested the temperature at the thermastat with a meter I have that is accurate to +/- .1 degree and also my Digital MultiMeter. The temperature meter and DMM both agree - and the thermostat is off by quite a bit from the other 2.
Sorry for this very long post - and I appriciate all your input!