E350 (Ambo) burning plastic smell in cab... vents?

[Bikersmurf]

This morning when I hopped in the ‘97 E350 there was the distinct smell of burning wire insulation. Best guess is from the vents. It got worse while driving. Ambo unit powered down.

google points me towards the heater motor &/or resistor. I swapped in a lower mile ‘01 blower a couple years back.

thoughts? Which way should I dig.

no smell under hood or outside.Nothing in foot wells.

So far everything still works and I’ve not seen any flames

 

[CaulkinsCo.]

I have melted 3 of the plugs that connect to the fan switch. If the blower motor is old it draws more amps I think. Or it's just a bad connection design. Anything else that's melting should blow a fuse.

 

[Bikersmurf]

While I was at it I noticed the dog house was loose, and it was louder when I fit it back on. A small bend with a wrench quite things down again.

 

[Bikersmurf]

I have melted 3 of the plugs that connect to the fan switch. If the blower motor is old it draws more amps I think. Or it's just a bad connection design. Anything else that's melting should blow a fuse.

Sounds likely. I’ll check

 

[CaulkinsCo.]

If I remember correctly last time I went through a bunch of vans at the junk yard before leaving with a only slightly melted plug, seems common. You can also ********** the floor hooks with a hammer to pull the dog house down a bit.

 

[iggi]

View attachment 571079View attachment 571080
While I was at it I noticed the dog house was loose, and it was louder when I fit it back on. A small bend with a wrench quite things down again.

Good tip!

 

[iggi]

Pop the heater fuses/s and see if the smell goes away?

 

[Bikersmurf]

Pulled out the heater and resistors. They're not the source of the smell. Resistor plug is brittle, but none of the plugs are melted.

In the process I did find that the + battery terminal connections were loose to connect the second battery. The -- terminal is also almost dead. Cleaning them up has improved some issues... it'll now not die randomly when the battery under the hood is out.

It's too soon to tell for certain, but the alternator output seems more consistent. Occasionally in the am it has gone up to 15.1 volts recently. Not really a big deal, but over 15 volts and my power inverter shuts off for a while due to high input voltage.

I can still notice the smell, but it isn't getting stronger and may just be residual. I'm going to keep monitoring it, and fix the 23 year old + battery terminal.

Now to decide if I dig out a spare Diesel OEM + lead and rewire the + battery starting circuit with it... or convert the + terminal to a marine style connection and attach the 3 heavy (0-1 gauge) battery cables to it. The Ford cable is a beast and has two leads about 4'+ long, so it almost seems like more of a headache than it'd be worth.

I've seen a couple ways to do it... I'll have to search around to find them again.

 

[Bikersmurf]

Picked up new ends on Amazon. I decided there wasn’t enough meat in the terminal to hook up the third lead. For the third I had to get creative. I’m not sure if I like the plastic terminal covers.., but for now they will stay.