I have a coupe and I thought I noticed the seat heaters were not working either. I will definitely re-check them tonight to see if they are working, because I'm taking the car into the dealer tomorrow for something else.

I recently installed some stereo stuff in the car. If the heaters are not working, I hope the dealer doesn't blame it on my stereo work.

 

It sounds like there is some control that prevents them from working. For instance, my low-mode worked wonderfully this morning but switching it to hi-mode was the same thing as turning it off (cooled down).

I know you'll definitely feel it too because the hi-mode is often uncomfortably hot. Regardless of the ambient you should be able to feel it. Also my car will be well cool after a 30 minute drive with the A/C on so the surface of the passenger seat has cooled yet with the heater on you can't feel any warmth.

Ask the dealer if they know anything about it. My buddy with a Jeep told me to put the heated seats on for my back (which has been bothering me as of late). He drives year round with his heated seats on (even if it's 100 degrees out).

 

On high the heater has a temp sensor I believe that cycles. On low it does not cycle. Maybe its sensing its too hot inside the car already so it thinks the heater is hot? I dunno just a guess.

 

The elements are protected with thermal cutouts.
After they cool the element will energize again.

 

I got my 05 in late April. Recently I tried out the heated seats and only the passenger seat got relatively warm but the driver's seat did not. I will bring it to my dealer the next time I go. It looks like Infiniti dropped the ball in their design of heated seats as there are too many problems it appears based on this post.

 

I wouldn't go as far as saying that. Mine worked FLAWLESSLY in the winter. I think what Russ said above might be the case. No body runs heated seats when it's 80+ degrees outside so there's probably something built-in to disable them or partially disable them because they can accidentally be turned on pretty easily.

 

Based on my car that is not the case because 1 seat worked and the other did not in 90+ heat. I think it would be tough to defend the design of the heated seats in the Infiniti as there appears to be many cries of dissatisfied people regarding heated seats.