First off thanks in advance for any help I may receive, My problem is this I have a 1999 GMC suburban K2500 7.4L with front and rear A/C. The electric cooling fan is not working. I am not getting any power to the unit, I have verified that all fuses and relays ( by swapping with starter relay ) are working. I have supplied 12v directly to the fan and it works, I have also replaced the temperature sending unit by the thermostat housing. I feel I am a pretty good do it yourselfer, but my "brain is burning on this".