Lights dimming.

95 escort LX. The car has been preforming well as of late, but one thing that is odd, is when I am driving and turn my heat on, all my lights on the car dim to about 50% for a second, then back up. Looks like I am flashing my beams at oncoming cars when I turn on the heat. Is it possible that my fan is drawing too much current? Or maby just a weak alternator? The car still charges fine when running, and I have never had a problem with a dead battery so I think the alternator is good.

Any suggestions on things to check?

95 escort LX. The car has been preforming well as of late, but one thing that is odd, is when I am driving and turn my heat on, all my lights on the car dim to about 50% for a second, then back up. Looks like I am flashing my beams at oncoming cars when I turn on the heat. Is it possible that my fan is drawing too much current? Or maby just a weak alternator? The car still charges fine when running, and I have never had a problem with a dead battery so I think the alternator is good.

Any suggestions on things to check?
First of all, turning your heat on isn't gonna cause your fan to come on. Your defrost mode might, and will cause your A/C clutch to cycle.
Sounds like your brushes in your voltage regulator are starting to go bad. Sometimes you can't buy it seperate from the alternator. Try doing a charging test. Starting with the battery.

First of all, turning your heat on isn't gonna cause your fan to come on. Your defrost mode might, and will cause your A/C clutch to cycle.
Sounds like your brushes in your voltage regulator are starting to go bad. Sometimes you can't buy it seperate from the alternator. Try doing a charging test. Starting with the battery.

Well, it was a used alternator when I replaced it last year, so that may be the issue. Can I check the current output by simply putting my ampmeter in series with the positive line coming off the alternator? Or is there a better way of testing this thing?

My car does this whenever I turn the A/C on. It's caused by the initial draw of the cooling fan motor coming on. Do you have the A/C button pushed in?

My car does this whenever I turn the A/C on. It's caused by the initial draw of the cooling fan motor coming on. Do you have the A/C button pushed in?

Definatly not, its far too cold to use the A/C :)

There is indeed a fan that starts up, so far as I can tell it must be drawing too much power initially. I'll try another alternator from the boneyard to see if my results differ, I'll return it if not.

Forgot that it's cold some places. I'm in Yuma, Arizona. If the cooling fan behind the radiator is coming on then a momentary dimming is probably normal.