A medical catheter has an inflatable balloon assembly on its distal portion and a plurality of ablation electrodes disposed on the surface of the balloon assembly. Conductors extending through the shaft supply the ablation electrodes with electrical power when connected to a power source. A plurality of thermistors on the balloon assembly are connected to the conductors to form a resistive network, and a plurality of access points on the conductors are provided for obtaining electrical measurements and analyzing the measurements to determine respective resistances of the thermistors.
