Last winter I noticed my heater not working. So before winter I want to find a fix. I assume it's the heater core but wanted some other opinions. I'm doing a lot tomorrow and may tackle this as well. Already on list for tomorrow: Plugs, fuel filter, air filter, throttle body cleaning, and oil change. I did a radiator flush today. Also my A/C has not been great lately. I have noticed that if I turn the AC off and then back on it gets colder quick. I guess it turns the compressor off and then back on? I'm not an A/C guy. Would the heater not working and the AC not working great be caused by the same problem? I turn the heat on today just to see and it blew cold air. Any ideas? Thanks alot.

 

Last year I remember disconnecting battery for 15 minutes and then the heat working fine for a couple of days. Something electrical?