06 Nissan Murano Heated Seats on High Turning Off

I bought an 06 Nissan Murano, it has heated front seats. The seats have two settings, low & high. Both seats work fine on low, they keep heating till I turn it off. The issue is with the high setting, I turn on either seat and it warms right up. For about 5 minutes, then nothing. My dealership check it out and said the switches, pads and wiring are all good. I didn't believe them so I tested all the wires, pads and switches with my multimeter, everything seems to have good continuity. Upon doing some research I found that somewhere along the line there is a thermostat that will disable the heat. My question is, is this normal for the heated seat to work for about 5 minutes and stop while on high (Again, happens on both seats only on high setting)? I'm a application analysts, so this isn't really my area of expertise. However, I'm not sure if there is really even a problem here of if this is how this system works. Any help would be appreciated, if y'all think there IS something wrong I'll go back to the dealership but I need something to back up my claim.