Burning smell coming from vents when the heater is on hot or cold


#1

I have an extreme burning smell coming from my heater whenever it is on, curious I put the fan on cold and it still has the burning smell. I pulled over and got out of the car he popped the hood and I don’t smell anything underneath the hood. Any ideas?? I’ve been leaving it off because I don’t want anything blowup on me


#2

You don’t mention the vehicle we’re talking about here, but if the blower motor is running at any speed below high speed, the voltage passes thru a series of resistors to the blower motor. These resistors get hot from reducing the voltage to the blower motor to reduce it’s speed.

If there’s any debris in contact with these resistors it can cause a burning smell.

These resistors are mounted very close to the blower motor so they’re cooled by the blower motor.

So have someone remove the blower motor, and then reach up into the plenum and feel for any debris near the resistors.

Tester


#3

+1 for @Tester. Also, sometimes these resistors will emit a burning smell when they are on the verge of burning out even if there is no debris present.


#4

It is a 98 chrysler sebring convertible, and the low and medium don’t work on it, it only turns on on high


#5

If the low and medium speeds are not working, that could be caused by an over-loaded fan motor. Debris maybe is preventing it from turning freely, interference between the cage and the house, the bearings have seized up, etc. I think you’re going to have to remove the blower motor for a look-see. Otherwise you risk something else getting burned up, including your car.


#6

Here’s the resistor block for the lower speeds for the blower motor.

https://www.rockauto.com/catalog/moreinfo.php?pk=2194956&cc=1314193&jnid=444&jpid=1

See those springs?

These get hot at lower speeds with the blower motor.

If the fan is set on high speed, the high fan speed relay by-passes the the resistor block.

Tester


#7

Could this be why I only get like warm air instead of actual heat comin out of it


#8

You will need a new resistor block, but you may also need a new blower motor.

If you do remove the blower motor, give it a spin by hand to be sure that it is spinning freely.
If it doesn’t turn a few revolutions by hand when you spin it…the bearings are shot and a new fan motor is needed.

If a bearing is going bad on the blower motor, it can create enough drag that it will burn out those resistors. This could be what caused the resistor to burn up now.

Yosemite


#9

“Could this be why I only get like warm air instead of actual heat comin out of it” Have you checked your coolant level. Low coolant will cause no heat.


#10

A blower motor on its last legs will emit a burning smell. Same with the motor in any kitchen appliance or power tool.