I have a voltage drop to about 9-11volts or less when I run the A/C in my camaro. Its a 92 TPI car. If I use my blinker it starts to go even lower. I put on a new battery, starter, and altenator. I had my charging system checked while it was running at Autozone and they said that its putting out 12V on their diag equipment. I replaced the starter cause I thought the soleniod was going bad cause after I drove the car for a while and turned it off sometimes it would hesitate or not start at all. Then if I let the car sit for a few, say 15 minutes, it would start right up. I guess my question is does anyone else have a voltage drop when its hot outside and you run the A/C. sorry for the novel..thanks

Josh

 

Hell yes I do. I note a drop from 14 - 15 volts to 11 or 12 when the engione fan kicks in. My A/C doesn't work, so no comparison there. When my turn signal is on, you can watch the bounce on the voltmeter.

You're fine so long as your not hitting 8 volts or anything! All of that crap draws on your electrical system so you should see movement.

 

Don't worry, it's quite normal. Mine does the same.

 

You should see a drop of voltage with the air conditioning on, HOWEVER, your voltage should still be in the high 13 to low 14 volt range---even with air on.

Modern, computer equipped venicles MUST have AT LEAST 12 volts at all times and at least 13 is what is really needed.

You have a weak alternator. It should put out near 14 volts.

jms

 

"Modern, computer equipped venicles MUST have AT LEAST 12 volts at all times and at least 13 is what is really needed."

Glad I don't have one of them new-fangled "modern" cars!!!!

 

I dont think I have a weak Alt. I just put a new Alternator, Battery and Starter on it. It seems to only drop in Voltage the worse when its a HOT day.

 

Please dont take this the wong way, but I dont understand how some of y'all think. You got a problem with the volts. when you turn the A/C on, so you change the Alt., Bat., & starter, but dont look at the A/C.
Have someone check that the A/C is fully charged and working properly, particularly the A/C compressor clutch. Make sure the wires going to it are not over heating and that the connections are clean. When Autozone checked the voltage, was it with the A/C on. If so you would have to consider the possibility that the gage is in error, not that uncommon. If you are getting a higher when normal power draw, from the A/C, this should show up as a low bat. volts. after you shut the engine off.
What amps. rating is the replacement alt.? I wouldn't want anything less then a 140 amp'er. on a modern car.
Bottom line here, is that your system should be able to maintain 12-13V's with every accessory on. Bad grounds and dirty/corroded connections cause more electrical problems when just about anything else, check'em.

 

Yeah I think my alt only puts out like 80 - 90amps. Thats the factory stock alt that I got at Autozone. Ill have em check the volts when I have the A/C on next time. I dont remember if I had it checked last time with it on. As far as the cables go I replaced both battery cables and regrounded the battery and the body to engine ground. I think my alt is not putting out enough amps. I think it should be at least 100+ not 80 or 90 like it is.

 

I just checked it out. its a 105amp alternator. I dont know what angle to take. I had a hesitation when I went to start it today. Once before when I went to start it it didnt even turn over. Then I let it sit for like 10 minutes and it fired right up. I hate little gremlins.

 

not starting when hot could be a bad starter,

is your belt slipping at all?
could be the A/C loads up the belt causing it to slip on the alt

 

check/clean your battery cable connections(at the battery and at the engine)

 

I had the same problem you did. My alternator was also around 105 amps. I bought a Powermaster 140 amp alternator and that solved the problem. The reason I bought the 140 amp alternator was that I also purchased an electric water pump and wanted it to run at full power at all times. Mission accomplished. By the way the voltmeter in my car reads lower than whats at the battery when the car is running and all accessories are going.

 

a healthy charging system should be between 13.5 and 14.5 volts at like 2000 rmpms or so.
id say your system is way to low and chances are your running off batery only.
just for ****s an giggles check the cooling fan fuse and see if thats blown if it is that could be the source of your low charging voltage since the charging circuit is fused through there.

good luck.

 

Sounds like a faulty connection somewhere to me. Do what Dave said and check/clean yur battery terminals. A corroded terminal will give you symptoms like you are describing.

 

Particularly the connection where the negative battery cable connects to the engine block.