Yes, I'm talking about PWM control using FETs. Many devices (such as brushless fans), AND Peltiers don't like to see a "chopped" waveform, so you should filter the PWM signal to pure DC. Also the PWM frequency should be above 20KHz, so that it doesn't generate any noise in the audible range. Basically, the simple circuit where you connect a FET Drain to the load's (-) terminal, the FET Source to GND, the FET gate to a PIC pin and the load's (+) terminal to 12V just won't do.

At current levels like this, you will need a FET driver, a big FET, an inductor, a Schottky diode and some capacitors that can handle high ripple currents.

I asked about the use because I just got an RFQ from a military customer that is using Peltiers. I didn't want to compete against myself.