The passenger compartment heater/AC fan in my '94 850 sedan works fine. However, the expensive resistor, Volvo part #9137937, that varies the voltage for speeds 1-3 has just died again within days of being replaced. That resistor has a single-use thermal fuse, which has now blown.

Here are my questions
1. Is the fuse really set for 216 degrees C as its markings imply?
2. Anybody know of a source for replacement fuses? They have GOT to be cheaper than $57 (lowest price I found online).
3. Any reason why I should not just jumper across the thermal fuse? (Yeah, I know this might be silly, but it seems to me that there is little reason why a component IN THE CABIN A/C airstream should EVER get that hot.)
4. Any reason why I should not put an external DC current fuse holder in place of the thermal fuse so that I can experiment with various amperage fuses as protection? And the motor already has its own fuse...
5. Might the Volvo part be faulty?

and finally,

6. Any reason why my electrical system should be putting out enough current to fry the heater resistor thermal fuse in the first place? As I remember from high school electricity, resistors absorb current by turning them into heat. More current or voltage, more heat. Since my resistor's thermal fuse failed, might that mean that the resistor is sinking more current and hence getting too hot.

Thanks.