For a few weeks now I have been chasing a hot, almost burning, smell, coming from the airvents when I have aircon and lights on.

For a while I thought it was only when the driving lights and aircon were on, but today I had the driving lights off, headlights on dipped, driving in the rain with aircon on and the smell arrived.

My best guess is that it might be the blower module getting extra hot, and maybe there's some foam landed on it and melting. My vette is converted to right hand drive and the airbox is inverted so the module is at the BOTTOM.

I replaced the module a few months ago, it's a real PITA to get to, from under the car, otherwise I would certainly pull it out and see - I may still have to do that.

The smell gets bad, no smoke but builds up in toxicity till I have to either switch aircon off (leave blower on and no smell) or switch lights off.

The fault may be slightly intermittent - for a while it would only do it when driving lights on (no headlights). Once when I had the smell with driving lights and aircon on, I turned the driving lights off and headlights on, and the smell disappeared. But today the smell came with D/L off and headlights on.

I have turned the driving lights on in the garage (engine off) for over 5 minutes - no smell. Did the same test with just headlights - no smell.

I hope there's an expert that either recognises the problem or can suggest where I start looking.

To Sum up -
1.Aircon runs for hours, no smell.
2.switch on driving lights or headlights- the smell begins within 2 minutes
3.Fault may be intermittent or dependent on other things being on, like coolant fan or wipers.
4.Smell comes out of airvents with blower on
5.No smell in engine bay


S'nut

 

48 views and no replies - that tells me this is a hard one!

I'm looking for any clues as to where to start looking.

Getting back to the blower module underneath the car is a PITA but I think that's what I have to do, and see if maybe some loose old foam has blown down there and sticking to module, then semi burning when the module gets hot - but why does the module get hot when the lights are on? There's no smell with aircon on for 2 hours - turn lights on and usually smell begins within a minute or two.

How could that happen ?

S'nut

 

Yep it is a tough one.I can only guess but if it only does it when lights are on I would be looking at that ckt.These car suck outside air in unless you are in recirc mode so it may be under hood smell getting pulled into the vent.Have you tried to turn on the recirc and does it do it then that is if you have the recirc button.Try checking it when parked with the hood up and sniff around.

 

You might unplug the cockpit fan motor and turn the headlights on and start sniffing. Headlight and fog light current goes through the headlight switch and the high beam switch (headlights only). Air coming out of a vent may blow hot insulation or switch odor from the headlight and/or high beam switch into your face making it seem like its coming out of a vent.

 

Since you seem to have the problem under high electrical loads, check ALL grounds very closely.

 

Thanks for the replies - there's no underhood smell, have checked with lights on for 5 minutes - no engine running.

Have also checked when smell is coming out the vent - no underhood smell - and i had the dashboard lid off, so could feel the headlight switches and sniff them too!!! - smell was still coming out the vent, and I used the vent nearest the blower motor to sniff test, so I was as far away from the light switches as possible.

I think it must be the blower module (which was new in Dec) - or the heater/aircon fan (which was new 2.5 years ago)

I have wondered about the grounds -there's a bunch of them beside the blower (because my car is converted to Right Hand Drive and everything is upside down and on opposite sides of the car)

I can't understand how a bad ground would do this - but I will check - thanks all for your input

S'nut

 

I would check ground 201 behind the I/P, near the LH side of the Steering Column. That's a ground shared by your A/C and headlights that could cause a feedback issue if it's not clean tight and secure.

 

A bad ground(or partial) can work like a resistor and generate heat.It is possible.

 

It seems to me that he would want to disconnect the lights at the connector.
If the smell stops, then reconnect the lights, if the smell starts it's something in your light circuit.
Maybe your motors are thinking they're not at the stops and continuing to run? Stupid idea, but if your out of ideas, it's worth a shot.
Just curious, since toilet water spins the opposite way in Australia, does the water circulate the opposite way in the Vette?

 

Check in the diagram if there is no fusable link that is shared by the lights and the other loads. A fusable link can become quite hot when loaded just below the fusing level. It is not supposed to be loaded that high, but the left to right conversion may have given rise to connect hot wires to an other point.

 

Thanks everyone for the further thoughts - I appreciate all your ideas and will check them out this week.

[QUOTEJust curious, since toilet water spins the opposite way in Australia, does the water circulate the opposite way in the Vette? ][/QUOTE]

You know - this just might be the problem- ha ha (wish it was)

S'nut