Re: heating/cooling/climate problem
The compressor is controlled by an AC ECU. It gets signals from all over the place to do with temperature in the car, temp outside car, system pressure low side, sys pressure high side, engine speed and engine load. All of these inputs come from sensors. The first relay click tells you the system is powered, but the AC compressor not clicking in tells you that something in the system is not okay. If any AC pipes were moved or disconnected during the rad replacement, first call should be to the garage who did the work. It is probably something they moved, hit, split while doing one job that has stopped the AC working.