Q: When cooling fan turns on while driving the dash lights would flicker and rpm would drop then goes back to normal.

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When cooling fan turns on all lights would dim briefly and rpm drops (not to the point where it'll stall, just small jolt down) and everything becomes normal in a matter of a second. Sometimes the dash lights would flicker. This morning when i arrived to work and had the engine off for 10-15 minutes the dome light wouldn't turn on until i started my car where it came right on. I turned off the engine and the dome light was still working until another 10 -15 minutes later. The car cranks and starts fine. I replaced my batter about 2 months ago after it completed died and wouldn't hold a charge but, the alternator was keeping that battery alive for who knows how long. I also had to change the spark plugs and ignition coils as the spark plugs burnt out prematurely. Is this an issue of electrical short, alternator or cheap battery(450 Cold cranking amps 560 cranking amps?

My car has 140000 miles.
My car has an automatic transmission.

Nissan requires that the battery in 2004 Sentra’s have a minimum CCA rating of 355 amps. Therefore, your battery is adequate, unless it has failed of course. If lights dim momentarily when the fans come on, that means that the available voltage to supply the rest of the vehicle electrical system has momentarily dropped. Possible causes of that voltage drop include a faulty battery, a fault in the fan motor windings causing abnormally high current draw, a fault in the circuit (wiring) supplying the motor, or a faulty alternator. The battery can be load tested and all other necessary diagnostics performed to resolve this issue if you request an electrical inspection. If you request that service, the responding certified mechanic will get this diagnosed and resolved, right at your location. If you have further questions or concerns, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you to get the best possible results.

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