Acrid Smell like Burning when heater turned on - only on hot not cold

[Ben12345]

HI,

 

Could anyone advise what the likely cause of my heater having an unbearable burning smell when anything above Lo on the climate control?

 

This started about a month ago and means I cant put any heat through the climate control as it smells too much

 

Is this a wear issue or something else and how can it be fixed?

 

Is the heater a wearable or serviceable part?

 

Thanks,

[Ben12345]

Bump

[Gaz]

Possibly your blower motor starting to wear/burn out?

 

Can be serviceable, but it's more usually a take it out and replace the unit jobbie.  It depends on how much fiddling you want to do.

 

Is it an acrid electrical burning smell, and only there when the motor is spinning.  Just wondering if it's something else, but either way it needs investigating to be on the safe side.

 

Gaz

[J.R.]

Sounds like the series resistor block has melted, I believe it is a common failure although I thought it was not in the circuit on the highest fan speed.

[Gaz]

On 30/08/2023 at 21:25, Ben12345 said:

... when anything above Lo on the climate control?

 

Could it be the smell is there on 'Lo', but is more noticeable when 'above Lo' because you are blowing more of it into the cabin?

 

On 30/08/2023 at 21:25, Ben12345 said:

Is the heater a wearable or serviceable part?

 

The heater itself is ostensibly a small radiator inside the dash area.  It doesn't do anything clever.  Faults are more usually a blockage (no heat) or rupture, in which case you should see leaking coolant and have the sweet smell of hot coolant.

 

The fan motor, resistor block (per @J.R.), and motorised heater control flaps are another matter, and any of these might be causative.

 

Have you checked your pollen filter to make sure it's not rank and stinky?  They can produce some odd smells when going off 🤮

 

And just one further thought;  The Mk1 can have issues when the pollen filter foam seal degrades.  A fix is obviously to reseal the pollen filter with the appropriate cord or sealant.  The two rubber bungs in the plenum chamber are often removed to stop them getting clogged with leaves and other detritus.  With these out, more hot engine smells can find their way into the cabin.

 

Gaz 

Edited 4 September, 2023 by Gaz
A further thought.

[Ben12345]

On 02/09/2023 at 10:21, Gaz said:

Possibly your blower motor starting to wear/burn out?

 

Can be serviceable, but it's more usually a take it out and replace the unit jobbie.  It depends on how much fiddling you want to do.

 

Is it an acrid electrical burning smell, and only there when the motor is spinning.  Just wondering if it's something else, but either way it needs investigating to be on the safe side.

 

Gaz

Hi Gaz, Thanks for replying.

 

Yes it is an acrid smell like burning that becomes overpowering if the blower is left on too long (as in 30 seconds or more).

 

I don't notice it when its on cold, only when I raise the temperature even just a degree or two above the lowest setting i.e. 18 or 19oC then it starts to smell

 

Where is the blower motor, is it a dash out job to change it or is it accessible? Are there any guides you know of?

 

Thanks Again,

 

 

[Ben12345]

On 04/09/2023 at 09:57, Gaz said:

 

Could it be the smell is there on 'Lo', but is more noticeable when 'above Lo' because you are blowing more of it into the cabin?

 

 

The heater itself is ostensibly a small radiator inside the dash area.  It doesn't do anything clever.  Faults are more usually a blockage (no heat) or rupture, in which case you should see leaking coolant and have the sweet smell of hot coolant.

 

The fan motor, resistor block (per @J.R.), and motorised heater control flaps are another matter, and any of these might be causative.

 

Have you checked your pollen filter to make sure it's not rank and stinky?  They can produce some odd smells when going off 🤮

 

And just one further thought;  The Mk1 can have issues when the pollen filter foam seal degrades.  A fix is obviously to reseal the pollen filter with the appropriate cord or sealant.  The two rubber bungs in the plenum chamber are often removed to stop them getting clogged with leaves and other detritus.  With these out, more hot engine smells can find their way into the cabin.

 

Gaz 

I removed the two rubber plenum bungs in 2016 when I got the car as one of the first things I did.

I havent looked under the scuttle panel for a while though so will check the pollen filter to see what state it is in.

 

With regards the resistor block anywhere I can find any info out on this so I know what I am looking for?

 

Thanks,