Yes there is a seperate fuse for the seat heaters. HTDST RF is for the passenger side and HTDST LF is for the drivers side.
Its more than likely a bad element though (sorry), its flexible but the cold weather makes the seat brittle and will cause it to break (open circuit).
If you look under the seat you will find the heated seat module, there are two connectors going to it, the smaller one is for the seat elements, remove this and measure the resistance of the heater elements with an ohm meter, it should read between 5 and 10 ohms, if reads '0' then its a short ( and the fuse will be blown) or if reads infinity its an open (failed element).

passenger side is inoperative..switch light will go out after a second and relay clicks.
Fuse in the back is ok. Do you need to remove the relay from the seat bottom to get enough slack in wiring harness to test the ohms.?

Curious why if the heater is in three elements...why the other two wouldnt work, if only one was burned out... does one wire feed all three?

What'* the odds of a bad relay? Are the left and right side relays interchangeable?

The 3 elements are in series so a break in one will cause all 3 to fail.
Also because they are in series if you jumper the bad one out the other two will get too hot and burn out right away.
I have done this twice now to my own car and both times it was the bottom (seat) element.
The wiring harness is clipped in to the bottom of the seat, move the seat all the way forward to help gain access to the control module. The passenger seat heater wiring runs down the left hand side of the seat.

anyone got the gm part number for the heater element for the pass seat?
Does the kit come with all three pieces or can they be purchased seperately?