oz928s4

Stinking hot day up here today so running the aircon and on high speed and it sounded like there was something touching the evaporator fan....just a slight tick tick tick thought there might have been a leaf or something small in there.
Any way about 5 minutes later I start to get that smell that you dread....electrical.
I look over and from under the glovebox or actually in the glove box (couldnt really tell as i was mobile) i notice smoke. Shut down the aircon and blower motor and sweated it out. Got home and tried the system it all works but i didnt want to leave it on for to long and smoke it up again.
Any hints from a previous victim.

John Speake

Check that the clutch on the aircon pump still engages when aircon is switched on. My guess is that it does not.......

wg928

My take is "fan down"...fan noise then smoke, hmmmmm....best to run it at home and observe where exactly the smoke is originating, less likely to me will be from the central electric board below the glove box in the passenger footwell, all the best .

mj1pate

A fan grill (recirc?) is just above the fuse access door and just below the glove box. The resistor pack is in the duct above the grill, and the blower motor moves air via the grill. Either device is a possible culprit. ......stand to reason based on your symptoms.

Pay attention that leaf debris and mouse nests have been reported to have caused fires in the same duct, on account of the power resistor pack. It seems that removing the blower fan and resistor pack is not that difficult, with proper planning.

There are some very good forum thread pictorials on how to access/remove the resistor pack and blower fan. These saved me a lot of potential labor. Don't proceed until you have some of these in hand....otherwise the unbolted resistor pack will fall through the duct and it will be most difficult to reinstall, lacking adequate preparation. Bill Ball has excellent forum hints on preventing the resistor pack getting away, once its unbolted. Yes, bear in mind: once you pull off the harness plug and unbolt the 2 bolts securing the pack, it falls through the duct.

Good luck......

Arena996

This happened to me in my '82. I also thought it was the A/C, but i was the fuse for the front radiator fans. They had corroded contacts and it created eccess resistance and ended up smoking the plastic of the fuses from the heat and amperage. Don't know if this is the same problem as you but I would pull the pass. floorboard and check all your fuses for tightness.
JIM

mj1pate

Dang....I forgot about this one. This has bitten more than a few and can have effects beyond HVAC. The 25-30 amp fuse for HVAC related fans can produce enough heat to deform the fuse panel and cause opens and shorts with non-HVAC effects. The fuse panel should be periodically inspected, I would assume more often than once every 20 years.

oz928s4

Morning chaps.
Well I drove the car in this morning and did not use the AC...although John i did switch it on briefly and it did work and got cold the whole show.
So got the kids in the car and 1/2 way to town ...say 15 minutes in the smoke appears again. No blower fan no AC nothing on at all. I can even smell the meltdown of what ever it is. The electrical panel above the G/Box is sounding like it might be the culprit.

oz928s4

Resolved see final post

oz928s4

The reason for all the smoke was as wg928 predicted.
Both fan fuses are chenobled. The fix is to pull the fuse panel forward and pull the wires off the back.
They are female connectors so add an external fuse ..I will use 24 volt fuse with a 12 volt 30amp fuse for the draw. For anyone in the same predicament the signs are that when you pull up at the lights and the fans kick in due to temp rising as no airflow, it will load the fuse up and start the smoking. Alternatively when using the AC and both fans kick in it starts smoking. Clean the feed wires at the + terminal at the battery. Thats where it all started due to a loose connection, not at the terminal but where the 10mm nut is off the other side of the main terminal block.

Alan

The only cause of this is contact resistance at the fuse blades where they contact the fuse socket - there are no other effects.

Ensure you have clean and high quality fuses (everywhere - but especially for these 2 fuses). Don't clean the fuse blades - just replace with new. Unfortunataley once this starts to go bad the fuseholder is either damaged by the heat or corroded and its difficult to clean (possible to replace but a bit awkward - especially to source parts). Unfortuunately the fuseholders on the panel are only barely able to support the power load on these circuit - with any degradation they start to fail. When they start to fail they build up local heat which causes faster contact degradation and deformation (often completely melting the fuse body and fuseholder) and causing the blades to twist in the sockets - which makes it worse...

The ideal solution is to have better fuses/fuseholders somewhere else... though if kept in perfect condition they work fine - this is a great PM area - 2 new fuses every year is not bad insurance here.

Alan

Mrmerlin

I would also check the fan connections it is common for them to get corroded

mj1pate

Alan....just to clarify: Do you mean replace every fuse twice a year? Or replace the fuses in sections, 2 individual fuses every year?

Alan

The biggest offenders by far are the 2 fan fuses - for these I'd replace with new every year - for the others probably evaluate condition and reuse unless there are any concerns. I am not a fan of repeated plugging & unplugging of fuses this does not typically clean the socket - it just loosens it - which also creates issues - once per year (or maybe every 2 years if everything looks good) pull & replace at least these 2. I just evaluate all of mine annually but I have plenty of good replacements on hand too... and I get to look at the front & back of my panel at least that often.

Alan

oz928s4

Yes Allan you make a valid point.
Pulling the panel forward and physically checking all fuses from the rear is a great idea and probably would have saved me some concerning moments.
The meltdown was so bad that I couldnt even get 29 out of the slot.