Car stereo problems. Left side front and back speakers do don't work untill car has run for awhile. No crackling or sound of any kind until it decides to come on. Tried another radio with same results. Also noticed the open door chime is very faint but comes back to normal when speakers are normal, like at the end of a trip.
This sounds like a bad ground. You will need a shop manual that shows wiring schematics and ground locations as well as a volt meter for starters. Then you'll need to check every wire on that circuit and all the grounds.