Unfortunately I don't (as of yet) own a thermistor based, digital thermometer with at least .1 degree accuracy, in order to ascertain the proper functioning of a TCA. The one in my car does its job normally, except at the wrong temp. Cuts of way above 3.5C resulting in rapid clutch cycling and poor cooling. Thermistor deterioration is likely the cause, but the "brain" box could also be bad. The resistance at room temp could esily be measured using a DVM. If within spec then maybe the circuit in the box is faulty.
The unit has 12VDC power to it and is a variable resistor with a comparator circuit (set to circa 3.5C) and a grounding ciruit at the pin labeled "L". For those of you who have converted to r134a and are getting occasional evap freeze, it would be possible to add this item to your car by simply drilling a small hole on the discharge side of the evap box and inserting the modern TCA probe. I am told the ECU at pin #46 is all the same for all years. 12VDC to the unit and a wire between the "L" pin and #46 on the ECU should get you fixed up.
