dryer heater runs with door open

[EricU]

That ain't right, is it?  I didn't turn off the dryer but left the door open.  Came downstairs and it was obviously too hot down there.  Also smelled like the dryer was overheating.  Dryer was hot to the touch, so it obviously was still going.

There has to be an interlock that failed, right?  Is that normally in the timer switch?  It's a mid '90s (I think) Kenmore front loader.

Google tells me the door switch is failed. Nope, it would still be tumbling

[EricU]

further googling shows that the heater might be failed or the centrifugal switches in the motor might be failed.
Anything else I should check on when I have the cover off?

[Robert Adams]

Broken heating element. One side of the element is always hot and the other is switched. When it breaks it lies against the metal case of the dryer and makes a circuit and will basically be a 110V heating element you can't turn off. 

       This is why they they went from 3 prong to 4 prong Grounded plugs on dryers. Dryers operate on 220 for the heating elements and they use the neutral to get 110v for the motor. So on a 3 prong the neutral and ground are connected together. On a 4 prong the case of the dryer is only connected to ground. 
          With as dumb as the design is with dryers I find it baffling that the ONE item you use on a common basis in a house and the one that is most likely to electrocute you because of broken elements is the one that doesn't require a GFCI... 

         A hot all the time bare wire that is prone to breaking and then touches bare steel when it breaks and that steel is the massive case that the user touches.... Yeah great engineering design work there..

[Roly]

Broken heating element. One side of the element is always hot and the other is switched. When it breaks it lies against the metal case of the dryer and makes a circuit and will basically be a 110V heating element you can't turn off. 

       This is why they they went from 3 prong to 4 prong Grounded plugs on dryers. Dryers operate on 220 for the heating elements and they use the neutral to get 110v for the motor. So on a 3 prong the neutral and ground are connected together. On a 4 prong the case of the dryer is only connected to ground. 
          With as dumb as the design is with dryers I find it baffling that the ONE item you use on a common basis in a house and the one that is most likely to electrocute you because of broken elements is the one that doesn't require a GFCI... 

         A hot all the time bare wire that is prone to breaking and then touches bare steel when it breaks and that steel is the massive case that the user touches.... Yeah great engineering design work there..

Agree with a broken element .         But the case is grounded so there is no shock but the continuous heating is a problem.   The same issue is on many electric ranges ,ovens , and water heaters.   Roly

[Robert Adams]

Agree with a broken element .         But the case is grounded so there is no shock but the continuous heating is a problem.   The same issue is on many electric ranges ,ovens , and water heaters.   Roly

          On a 3 wire the body of the dryer is tied to the neutral and current carrying when the motor is running the light is on or the element is broken. On a 4 wire the case is grounded and the neutral is on it's own. No ground on the 3 wire ones.

[Roly]

          On a 3 wire the body of the dryer is tied to the neutral and current carrying when the motor is running the light is on or the element is broken. On a 4 wire the case is grounded and the neutral is on it's own. No ground on the 3 wire ones.

The neutral was also the ground on the 3 wire systems for years the only time it was a hazard is when you lost the neutral connection.  the same applies if you lose the ground connection  and the element touches the case.

[EricU]

The element was welded to the casing.  Makes me think I should replace the thermal switch, because I think it should have popped.