When car is getting old, the need to know basic troubleshooting is becoming necessary. There are several resources on the internet (e.g. forums) and I will just be putting some items here that I have also encountered while maintaining an old car.
==> A/C blower speed increases and headlights brighten intermittently without any pattern
– Possible Cause: Alternator is failing or some connections (maybe for the ECU) are disabled
– Solution: Replace the alternator
==> A/C blower speed increases and headlights brighten when accelerating
– Possible Cause: IC voltage regulator is not working
– Solution: Replace the alternator (though some would just replace the regulator)
==> Tail light (dual filament type) is not working for the first few minutes but is later functioning
– Possible Cause: One of the filaments is already failing. If the other filament (for brake light) is still working, it also heats up the neighboring filament and may establish connection after some time of driving.
– Solution: Replace the light bulb (not expensive)
==> Right/left turn signal light blinks faster than normal
– Possible Cause: At least one bulb is out.
– Solution: Look for burned-out bulbs and replace.
==> Engine is overheating even during early morning drive
– Possible Cause: Some of the radiator tubes/ coolant passages are already blocked; leaks from radiator tubes or the rubber hose connecting radiator to the engine; radiator cooling fan is not working
– Solution: Repair/replace the radiator or replace defective cooling components
==> Squealing, screeching or chirping noise under the hood
– Possible cause: Incorrect belt tension; belt pulley misalignment
– Solution: Adjust belt tension to the correct specification; correct any misalignment
==> Tires loosing pressure fast
– Possible Cause: Leaking tire valve; leaking rim; tire puncture
– Solution: Replace tire valve; lightly buff the tire bead and wheel’s rim; patch/ vulcanize tire
==> Knocking or popping sound when going over road humps/bumps
– Possible Cause: Worn-out shock absorber (or check also other components of the suspension system)
– Solution: Replace shock absorber or other suspension components
==> Radiator leaks
– Solution: Solder those leaking areas of the radiator; use “stop leak” liquid (e.g. Mag1), which would work well for small leaks based on my experience.