I have a tempstar ac/heater unit electeic.ac guy cam out today said heater was bad. Is it hard for me to change heater myself. It is only blowing 5kw and should be 10kw .he wants to charge me 400 bucks but I can buy the heayer at the ac shop for 135 new. Is it pretty easy to do all I saw was 2 wires and 2 crews on the stip.. help