Yes.
The "switch light" only indicates that there is power to the switch (fuse is good).
You need to take a meter and check for voltage at the window heat element.
With the switch on, then check for voltage at the window heat element.
No voltage at the window heat element = defective switch.
A warning story for anyone out there looking into this problem, power at the defroster switch (red illumination when the daytime running lights are turned on) doesn't always mean the fuse is 'good'
I had picked up some of these 'Glow when they Blow' fuses from Princess Auto. Didn't think too much to check them at the time. Had the defroster switch prematurely stop operation during a cold night run to the store. Red illumination was still present but the switch was not clicking in to engage. Thought the switch was dead internally somehow. I still had power at the fuse right?
After swapping out the switch with my mechanic, I still saw the same symptoms. At this point I suspected the fuse. Mk4 Jetta lists as Fuse 26. Fuse is one of those 'Blow and Glow' ones I had put in. Testing across the terminals indicated continuity but the fuse portion was clearly showing soot like it had blown.
Tested out other fuses I had around, same deal, the fuse portion would blow but the fuse was still letting trace power past. I reported them to Princess Auto. Word to the wise, check the fuse if you have a specialty type.