yaskota

MY 1984 US S...

New Behavior (to Me): What does it mean when... With ignition on (II or III), engine not running, click rear defogger/defroster switch on Pod to the right (i.e. turning on defogger) and there is a sick buzzing sound by CE Panel?

Turning defogger off stops the buzzing, of course. Turning on rear defroster = no buzzing. Car's voltmeter gauge dips when enabling either function.

Bucko74

Tom. any sort of buzzing from CE panel probably suggests a fried relay.. Does the defroster actually work?

I think the rear defroster is on a timer relay so even when you shut it off the circuit is still active for a short period (less than a minute if I recall).

yaskota

Aloha Bucko!

Does it work? Well, not yet. At least, I don't think either the rear defogging or defrosting functions are working. The relay is new however- and CE panel refreshed- cleaned, DeOxitized with all new fuses and new relays where applicable (like this one).

It's been suggested that there may be something else on the circuit that may be amiss and having an impact & it seems to me that, in concert with a few other electric daemons, this could indeed be correct.

The good news- I guess- is that before my CE panel refresh, turning either the rear defogger or defroster on did not result in any movement from the Voltmeter gauge. But now, with defroster? Movement. With defogger? Movement and buzzing...

I'll be digging deeper into this this weekend, WSMs and multimeter in hand...

Bucko74

Ok, at least you can claim progress.

Maybe check for mechanical damage to the actual element in the glass, sometimes they can get scratched which creates a short in the circuit.

Other than that, I have no suggestions. Jeez I hate electrics...

yaskota

20140802 Update (aka Cleaning Out the Cobwebs)

Since having a rebuilt alternator installed and installing a new battery, this symptom is kaput. I have yet to check to see if hatch glass defroster/defogger element is functioning properly (don't get much ice here in Hawaii!) but will try to test & report back w/in next day or two.

My totally unsubstantiated opinion is that it was buzzing as it wasn't receiving sufficient power. However, I could, and both may be and have been, wrong.

Dave928S

Sounds possible to me. Insufficient voltage has that effect on all sorts of energised coils, where they are on the threshold of holding current, they alternate the contacts between open and closed (and buzz), which can cause arcing and trash the contacts.

When voltage is on the threshold and it closes the contacts, the just switched load can cause enough voltage drop to cause the coil/contacts to drop out, then voltage fractionally rises, and it closes the contacts ... and so on ad nauseum. This phenomena is more common on heavily loaded circuits where voltage fluctuation is more severe/likely.

I've had exactly the same thing occur on heavily loaded switchboard contactors ... which are just giant relays.

If you still have the issue when you check again, go looking for a resistive connection or switch in that circuit, which could have tipped voltage drop over the edge with low battery voltage to start with.

Bucko74

Yeah, what Dave said....i'll say it again, i hate electrics.

Hows the rest of you restoration going, started anything else substantial?

yaskota

Thanks guys! That reminds me, I keep forgetting to post an update in my thread about one or two things that have transpired over.... the past month or so!

I did just order Zimmerman cross-drilled & slotted set and EBC Redstuff- both for my rears. Also putting an order together for some transmission parts connected to a slow leak. Other than that, in a moment, I think I may check that flap above the CE Panel for HVAC as I have another hot date coming up- but don't want or need that kind of heat!

switching over to post mega update...

yaskota

[UPDATE]

No longer buzzing AND defogger function working fine. Living in Hawaii, I certainly hope I never need the rear defroster but am fairly confident it works too...

What was wrong? My guess- and only a guess- is low power. When Ele gets to a point of low power again (as in electrical)- which she will as I'm still chasing gremlins- I'll test my theory, post another update and close this thread.

PS: Still waiting on new rear rotors...

Mahalo y'all...