Arrived at customers house for system not cooling. On arrival customer showed me to air handler unit. Air handler unit is currently running. Fan is blowing. Went outside to condenser. And outside is not working. Contactor is making a fierce, buzzing noise. Called customer and suggested we change out contact name. Customer agreed. Changed out contactor but system still not running. Pushed in Contactor and unit did not start. Tested capacitor and capacitor is below acceptable range on both sides. Pointed out to customer and suggested be changed. Customer agreed. Pushed in Contactor in unit now start. Still not getting anything across common I went inside and tested transformer. Transformer was not putting out 24 V across common. Put in new transformer and now getting 24 across secondary side. Unit is still not sending common outside to unit. Only other thing between what was corrected and outside Is the air handler board. Informed the customer of this and suggested she now get consultat