2014 ford mustang convertible
I've been having troubling get my car ^^ to start this past week. Sunday it began. I went to go start it and the dash and AC would turn ok but the engine wouldn't. I tried several times, waiting in between each and still nothing. I jump started it with a battery pack and that worked. Car worked normally for the next 30/40mins.
Monday, next day, it turned on and worked perfectly. I drove about 200 miles this day too, having the car parked for long hours in between too. No issues.
Tuesday, yesterday, it turned on fine and I drove abt 15 miles, parked it for about 4 hrs, and turned it on to return home just fine. I stopped at a McDonalds otw back, left it parked, and when I returned, it wouldn't start the engine again. Just like Sunday, the dash would come on, the AC too, but not the engine. Tried a few times again to start it. I had my portable starter pack with me so I tried jumping it again to at least make it to an Autozone to get the battery checked. It turned on after I had jumped it the second time, and drove to Autozone. Battery tested good and employee suggested a little kit to clean the battery turmoils because it seemed battery acid had started to leak a bit. Bought the kit and they cleaned then there.
This morning, I went to go start it and the first time it didn't start the engine, only AC & dash. Second time, it worked, started engine and everything else normally. Took it to a nearby O'Reilleys to get battery tested and alternator. Both came out in good condition.
Employee suggested it could be engine fans failing to turn off once the cars off since it has been very hot where I live and the sensors could be mistaking that heat and that could be draining my battery. But I am confident they are turning off properly as the car turns off.
I'm not sure what it could be now.
My next step i'm thinking is to take it to a mechanic shop to have it inspected even closer: for example... (I don't like using AI but turned to it as a last resort here.. ChatGPT suggested I take it in and say): "I have an intermittent no-crank/no-click condition on a 2014 automatic Mustang. The dash and accessories work normally, but sometimes turning the key to START produces absolutely nothing. The battery and alternator have tested good twice, and the battery terminals were cleaned. It has occasionally started after a jump. Please check the starter/solenoid, starter relay, park-neutral safety circuit/transmission range sensor, ignition switch, and battery/ground cables, including voltage-drop testing."
Is that an appropriate next step? I'm also very good about disconnecting and turning off anything that I plug into the car like chargers, etc., so it wouldn't be a drained battery from that.
What could the issue be?