Alan

I'm NOT saying there aren't possibly other functional issues with the car (who knows).

I AM saying none of them are contributors to the fuse getting hot - AND it makes no sense to pursue any of them that may be related to this until this issue is solved.

If the fuse is getting hot - it is dropping voltage across at least one of its contacts. This means the fan is running at less than full speed even in DEF mode...

It is conclusively NOT a resistor pack issue with this behaviour (if it is exactly as described) Its possible there is a resistor pack connector issue, a switch connector issue, or a Blower relay issue... however it makes no sense to do anything but fix the power supply problems though the fuse first... everything else depends on this - and its known to be problematic.

Dean to be clear:

IT IS JUST THE FUSEHOLDER TO FIX THE HEATING/MELTING ISSUE

Alan

Dean_Fuller

Thanks Alan....electrics has never been my thing. I will pull the fuse connector and clean first.

On another point. The A/C condenser fan relay is the same as the blower relay. I swapped those just to see and the smoke multiplied exponentially. I think I need to order a couple of those as well....does that help make anything clearer to you?

Alan

Dean its all clear to me... per post #17.

If swapping the blower relay caused more heat then likely that's the culprit for your lack of fan speeds - it was one of the possibles in my list. In that case the high speed fan mode (at least) in non DEF mode should also work with that replacement relay in place.

Alan

Mrmerlin

I would also Follow Wally and Alan advise about fixing or cleaning the fuse holder.
Also open up the blower relay and check its internal contacts see if it is corroded inside or the pins are corroded
Also it would be wise to investigate the bottom of the blower box for water leaks, if you can see rusty threads or white deposits trailing down the CE panel supports, then you should also consider resealing the blower box .
That said you should also inspect the rear side of the CE panel for melted wires, they can also be noted to have shiny insulation, this would indicate a raised temperature being passed through a wire. also look at the crossed wires for being melted to one another.
And inspect the resister pack and if you do the blower box reseal you should also clean the blower motor and lube the bearings you may have to clean the motor anyway

Dean_Fuller

I noticed that the relay for the window winders is the same part number....pulled it. It looks in good shape and the windows work fine. Put it in the blower spot and smoke galore and the fan still only works on DEF, HIGH....so NOW I tend to believe the relay is not the problem.

Alan

Now once again... where is the smoke coming from? - the fuse or something else?

When you replaced the panel - was it for the exact same year? - they are not all the same...

Are you saying it did the same thing even with the old panel..? the story is a bit fuzzy to me.

Alan

Dean_Fuller

Alan,
I know the new panel is from another 80 model. I knew at he time all the panels are some what different. I do have a leaky heater box and will reseal soon. For now the car LIVES in the garage and never sees water....Yes the old one had the same problem. The smoke is the plastic part on fuse #17 burning. I see NO burned or hot wires on the new or old panel. In fact as it is smoking I can touch the back of the panel up to wards #17 fuse and feel no heat.

Alan

OK - then the same diagnosis - more current - same resistance (of the poor fuse conections) = more heat.

Alan

Dean_Fuller

A really appreciate the help Alan...but I truly don't know much at all about wiring. See if I am following this right so far...

1) When the fan motor is unplugged at firewall with blower relay in place and heat turned on ...no smoke and no fan.

2) Good relay added, motor plugged in...SMOKE from #17 fuse and fan on high only on DEF.

3) no burned wires on the back of either the old or new panel.

4) Any time the blower motor is running I get #17 fuse smoke.

From all of this can I deduce that....fuse panel is good....relay is good....blower motor is ???? Sounds fine when running. Is there a way I can verify the motor is operating properly at the designed voltage??? The only thing else is wiring between panel and controller or the controller itself?

I know this sounds elementary to you but I am lost so far.

Dean

SharkSkin

One thing you can try is connecting the fan straight to +12v, fused @10A or so... if you have an ampmeter on your DMM that can take 10A you can measure the current. You can rig something with regular spade connectors. This will help you diagnose without letting anymore of the "magic smoke" out of the fuse panel. I'm sure you know by now, electrical systems run on magic smoke. Once you let all of the smoke out, they quit working.

Alan

The smoke & heat is still just the fuseholder... you have to fix it...

Once thats fixed you can see where you are on anything else...

...until then you can't see anything else for the smoke...

I know it's not intuitive to you (and to most others) but thats the way it is - if the motor were a major issue the fuse element would blow rather than the plastic fuse body melting...

The motor is not taking excess current to cause this - the normal or even less than normal current through the fuse is causing it to melt by heating it from the terminal end - not from the fuse element...

This commonly happens on the cooling fan fuses on the later cars - nobody wants to understand that this one is just a fuse & fuseholder connection issue either...

Alan

Dean_Fuller

Okay...removed the fuse holder from the panel and gave it a good cleaning with the wire brush dermal along with the wire connector for the top of fuse #17. Hooked all back up and smoke...but this time the wire got warm..not real hot just warmer than it should. The photos are of the OLD panel. The first shows the back of fuse #17 shown with black mark. That wire leads to blower relay...I marked the flow of wires with black sharpie. Looks like from there to the A/C condenser relay then ever thing leads to the "J" master plug at the bottom. I hope this helps.

WallyP

If a resistor wire is broken, the blower will still run at high speed. The resistors are fully by-passed on high speed.

If the blower will only run on Defrost, the most common cause is a faulty blower relay.

Dean_Fuller

I agree Wally...my MAIN problem first is to find out why #17 fuse is burning and smoking when the climate conrol is turned on....the fuse heats up without actually blowing.

WallyP

Back to Basics:

- Power flows from the battery bus to Fuse #17.
- From Fuse #17, power flows to the 30 Terminal of Relay XXI, the Blower Relay.
- From the 87 Terminal of the Blower Relay, the power flows to the input of the five-position Blower Switch AND to two different inputs on the Resistor Pack.
- On OFF, no power flows thru the switch, but power flows from one of the Resistor Pack inputs thru four in-line resistor wires to the blower, giving a small air flow.
- On Speed 1, power flows thru the switch to a connection between resistor 4 and resistor 3, increasing blower speed slightly.
- On Speed 2, power flows thru the switch to a connection between resistor 3 and resistor 2, increasing blower speed more.
- On Speed 3, power flows thru the switch to a connection between resistor 2 and resistor 1, increasing blower speed more.
- On Speed 4, power flows thru the switch to a connection between beyond resistor 1, thus bypassing all resistors, increasing blower speed to the max.
- If the temperature inside the Resistor Pack gets too high, a small thermal switch operates, by-passing the resistors and putting the blower on high. When the thermal switch cools due tot he increased air flow, it opens and the blower drops back to the selected speed.

- From Fuse #17, power also flows to the 30 Terminal of Relay XXII, the Defrost Relay.
- When the Defrost Relay operates, power flows from Terminal 87 directly to the blower, making it run on high speed.

Note that the power to run the blower ALWAYS flows thru Fuse #17. Therefore, regardless of what Alan and I have told you, Fuse #17 may not be the problem.
- If the blower will run on high speed on Defrost with no smoke, then Fuse #17 is not the problem.
- If the blower will run only on high speed in the Heat/Cool positions, there is probably a problem inside the Resistor Pack.
- If there is smoke with the blower running on the Blower Relay, but not on the Defrost Relay, there is probably a problem in the Resistor Pack or the wiring to it.
- If something is getting hot enough to smoke, you should be able to see discoloration or melting.