1999 Ford Mustang Fans not working, followed by smoke from

EFFIN99COBRA

MEMBER
1999 FORD MUSTANG
V8
2WD
MANUAL
75,000 MILES

My cars electronics have been acting up lately, here is a rundown-

-3 weeks ago my A/C quit working. However, the fans were still working. It was bearable.

-Just yesterday, the my entire ventilation gave out. The fans quit working. It's summer, and my car interior is getting uncomfortably hot.

-today on the way home from work, I noticed (and smelled) a trail of white smoke coming from underneath my hood. Not good. Pulled over, popped the hood and I noticed that the source of the smoke was coming from my battery (redtop optima). Smoke was coming out of one of the two small openings on the top of the battery.

I waited a couple minutes to let the smoke die down and fortunately I was able to start the car and make it home.

I really think I should buy a new battery. Anyone have any suggestions as to what else I should do?

Thanks, Ron

3 Replies

CARADIODOC

MECHANIC
33,871 POSTS

Hi effin99cobra Welcome to the forum. Use a cheap digital voltmeter to measure battery voltage when the engine is off and again with it running. With the engine off, you should find around 12.6 volts for a fully charged battery. If you find closer to 11 volts, there is nothing more than a shorted cell in the battery. Your 12 volt charging system will be, in effect, overcharging a 10 volt battery. The shorted cell will not smoke since the current just goes right through it without producing much heat. The good cells will overheat and smoke.

With the engine running you must have between 13.75 and 14.75 volts. If it is higher than around 15.0 volts, the battery is being overcharged. The culprit is usually the voltage regulator which is bolted to the back of the generator.

Caradiodoc

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Sunday, June 6th, 2010 AT 2:34 PM

EFFIN99COBRA

MEMBER
2 POSTS

Thanks for your reply. I took voltage measurements and the voltages were within specs, while the engine was running and not running. I verified that the ground cable from the battery was secured.

But now my battery has a weird bulge sticking out on the top. I am going to replace the battery, and from there, figure out why my fan and a/c isn't working. Do you have any suggestions on where to start?

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Sunday, June 6th, 2010 AT 4:20 PM

CARADIODOC

MECHANIC
33,871 POSTS

Voltage regulators can be intermittently shorted leading to an overcharged battery. Batteries can have intermittent problems too but it isn't common. As long as the battery is still working, I wouldn't replace it yet in case there is a problem that will damage the new one. Overcharged and frozen batteries will bulge the sides of the case. I've never seen one bulge the top.

For a dead fan, start by locating its connector and taking voltage readings on the two wires. The black meter lead should be on a clean paint-free spot on the body, or a ground bolt, then use the red lead to probe each of the two wires for the fan connector. The readings will mean more if you back-probe the terminals while the connector is still plugged in and the fan switch is turned on.

Caradiodoc

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Sunday, June 6th, 2010 AT 4:40 PM