Today I was doing a coolant pressure test. I know I was supposed to disconnect the battery beforehand but I've had issues with the terminals connecting properly in the past so I left it alone because I figured the vehicle was off and hadn't been driven in hours. I disconnected the two sensors attached to the air intake and removed the air cleaner assembly box so I could get a better view of my hoses. At some point I got in and turned the key (not to start the car) just to turn the lights on, but I immediately noticed my heater was on and blowing (the sensors and assembly were still disconnected at this time). I quickly turned the heater fan off and turned the key back to the off position and removed it from the ignition. At that point I heard 3-4 very quiet popping sounds coming from inside the dash behind the steering wheel. My question is, do you think the quiet popping sound was related to not bleeding the coolant system yet, an electrical short, or just air sounds?
My car has 130000 miles.
My car has an automatic transmission.
If your truck has automatic climate control, what you heard could have been the air diverter doors moving back to their default position. We used to joke about some cars sounding like there was a little guy inside the dashboard running around slamming doors when you turned off the car. If it isn’t that, I’m not sure what to tell you except that turning on the key while the sensors were disconnected is liable to give you a Check Engine Light the next time you start up the car. The controller performs a system check as soon as you turn it on and it will see the sensors that are disconnected as being defective and store a code. If you are nervous about this or the sounds in your dashboard you can contact YourMechanic. They can send a technician to your home or office to check out your noises and let you know what is going on.
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