Short answer: YES, they are on "max heat" without a controller.
When I first got a pair of heated gloves, they didn't come with the controller. With one of the wires inside sticking through the insulation, they burned my hand. I wish I had simply gotten a controller at that point, and tucked the wire back in. Instead, I contacted Gerbing, even though I bought the gloves on eBay, and they only had 2 questions: What size?, and where do we send the replacements? The replacements I received didn't get as hot, though they've done fine even down to 17 degrees without the wind chill. I have since gotten a controller, but it doesn't allow them to get as hot as without the controller. I also got an inline switch, which I will likely use when it gets well below freezing, avoiding the controller. Above freezing, I'll probably use the controller, but I hardly need them to be plugged in above freezing, due to the hand guards I have installed.

 

Probably not as bad on the newer bikes with 50 amps available, but the older bikes with 22/28/32 amps could be taxed to run the controllers. The older controllers (rheostats ) shunted the excess power, essentially wasting it. Perhaps the newer variable controllers are more efficient?

My first two vests had the on off switch, and I just made sure it was in a convenient place to use while riding. And a proper fuse was used.

 

Not sure where you bought it, but the H-D dealer had all that stuff on the shelf last time I looked for something for my wife.. Get another one.
Been awhile though.

 

Those Gerbing controllers suck. Went thru 2 of them in 5 years. Now I connect my gloves and jacket liner direct on both my Shovelhead and FXDX. I wear them when layering up isn't enough so I don't mind them being on max output all the time. Never had a problem.