Rear defroster switch blink!!!

[Uncle Benz]

Hi folks,

Very curious: Here in Montreal, cold had started, snow, ice rain etc. So, has usual, I started the car and put the air control to defrost and also activate the rear window defroster.

This is the 3rd time it does this : Once the switch is on (of the rear defroster), the light of the switch goes on (of course...) BUT, the light start to blink (regular blinks)!!!!!!!

After turning the rear defroster off and back on again, it doesn't doing it again.

WHAT THAT MEAN??? Is this a signal for an electric problem? Witch one??

Thanks to help me!
Uncle Benz

[Cdn190er]

hahahahaha you guys lost the Gray Cup


To be honest this is the first time I heard this and the only thing I can think of is not enough power from alternator. Try this - leave the fan on 2 and only the /\ pressed and then just turn on the rear window.
Or if you have the defrost - bring up your RPM to 1500 and see if it blinks.

[mctwin2kman]

Blinking means there is not enough juice to operate it. Instead of it killing the battery and alternator it turns off under a certain voltage. If it is cold out and you draw the battery down by starting the car and then immediately turning on the rear defrost that is most likely the problem. Too much juice wanted at once. I never turn on the heater until the engine is warmer. No sense blowing cold ass air out the ducts. I also wait a bit before rear defrost to let the battery and alternator catch up after a restart. On my W203 it is a different story. I turn on the heated seats as soon as the car is started, sometimes before. But I leave the heat and re-defrost off until after startup. Then I still do not turn on the heater until after the engine is at least at over the 40 degree mark.

[Uncle Benz]

Originally Posted by Cdn190er

hahahahaha you guys lost the Gray Cup


To be honest this is the first time I heard this and the only thing I can think of is not enough power from alternator. Try this - leave the fan on 2 and only the /\ pressed and then just turn on the rear window.
Or if you have the defrost - bring up your RPM to 1500 and see if it blinks.

Yeap we lost and not far to win. Good game but hey, next time the cup will be back to Montréal!!!! Hahahaha! :D

Hummmmm, concerning the blinking switch. I will try your suggestion and see how it will react. Tell me mon ami, why putting the fan at 2 with air only /\?? I dont see the relation between both defrosts. But you have a good idea about bringing the RPM to 1500. If the blinking goes away that mean that my damn alternator is failing...Shit!!! Is it expensive? And could it be the battery?

Uncle Benz

[yvrbenz]

Originally Posted by Uncle Benz

Tell me mon ami, why putting the fan at 2 with air only /\?? I dont see the relation between both defrosts.

because the defrost button runs the fan at full speed. by putting the fan switch on 2, you still get some defrosting done but with the fan at a slower speed which means less draw on the charging system which, in turn, means more power left over to run the rear defrost.

[Uncle Benz]

Originally Posted by mctwin2kman

Blinking means there is not enough juice to operate it. Instead of it killing the battery and alternator it turns off under a certain voltage. If it is cold out and you draw the battery down by starting the car and then immediately turning on the rear defrost that is most likely the problem. Too much juice wanted at once. I never turn on the heater until the engine is warmer. No sense blowing cold ass air out the ducts. I also wait a bit before rear defrost to let the battery and alternator catch up after a restart. On my W203 it is a different story. I turn on the heated seats as soon as the car is started, sometimes before. But I leave the heat and re-defrost off until after startup. Then I still do not turn on the heater until after the engine is at least at over the 40 degree mark.

So, if I understand well your explanation, this is absolutely normal. So I should just not turn everything on...

If so, thanks a lot for your help mctwin2kman and yvrbenz! And of course my Canadian friend CDN190er!!!
Uncle Benz

[lxcxs]

OMG this is the damned third time I have the same problems as you, Yves !!!



The lil light started blinking so i turned it off then turned it back on.All was well


I also have this weird bug : if i spray my windshield sometimes, the wiper blade does its thing but then doesnt go all the way down like it should.So I do it again, and higher up it stays, and then a 3rd time it goes back down.
Mind you this was on the highway but still....

Then if I just click the windshield wipers while I spray and THEN turn it off, no problems.

What gives?

Uncle Benz, you too ?

[Uncle Benz]

Originally Posted by lxcxs

OMG this is the damned third time I have the same problems as you, Yves !!!



The lil light started blinking so i turned it off then turned it back on.All was well


I also have this weird bug : if i spray my windshield sometimes, the wiper blade does its thing but then doesnt go all the way down like it should.So I do it again, and higher up it stays, and then a 3rd time it goes back down.
Mind you this was on the highway but still....

Then if I just click the windshield wipers while I spray and THEN turn it off, no problems.

What gives?

Uncle Benz, you too ?

NOP my friend, not this time! The only problem I had was last winter when my blade was iced. It jamed there but the motor was running. I found that it was just unscrewed. Guess this is designed on purpose (to previent burning the wiper motor). I had this on my Vanagon too!

I dont know how to help you. Sorry mon ami :(

Uncle Benz

[mctwin2kman]

Originally Posted by Uncle Benz

So, if I understand well your explanation, this is absolutely normal. So I should just not turn everything on...

If so, thanks a lot for your help mctwin2kman and yvrbenz! And of course my Canadian friend CDN190er!!!
Uncle Benz

You got it buddy. Just wait a few more seconds to a minute to let everything get to where it needs to be power wise. Should not be a problem then. Remember the colder it is the harder the alternator has to work and the less power flows nicely.

[syf]

Hi all! First post for me.... :)

So, my rear defrost was blinking on me tonight. Alternator was replaced about 7 months ago. I'm in Seattle, and the temps were right around 50-55, but a HEAVY downpour... which means I was running my windshield wiper at full blast. Not gonna lie, I love doing that.... So in total, I had both defrosts on, wiper at max, headlights and fog lamps on, plus stereo. From what I am reading, it would not be outrageous that this was drawing a bit too much power, and causing the rear defrost switch to blink. Should I still be concerned, or is this normal?

Thanks!

btw I have an '87 2.3 8V

[mike919]

were all of the interior lights blinking or just that one?

and welcome to the rev.

[dan_189]

Perhaps try upgrading the cable from the alternator to the distribution block? I am no electrical expert however I did it so my sound system wouldnt strain the system and it made a huge difference. I also noticed that the defroster uses a lot of power so it showed me on the volt gauge

[syf]

Hi!

Only that one switch was blinking. As far as the cable upgrade, do you mean a heavier gauge cable?

Thanks for the replies!

[dan_189]

Yes heavier gauge cable such as 4awg, thats what I used from the back of the alternator to the distribution block near the left strut (follow the original wires).
The car felt a lot better, transmission shifted much smoother big improvement from 12v or below to just under 14v :) (according to the volt gauge)