I have a mini fridge that uses a Peltier chip to lower the temperature. Said chip has burned out, and the unit which used to reliable cool to 40f now stays at 78f. I replaced the chip with one from a smaller, lower power cooler and could get the temps to 50f but no lower.

The original peltier in the fridge I am salvaging was 12v 50 watts. I bought a 12v 90 watt one a as replacement. The fridge is powered by a 250 watt PSU at 10 amps. The peltier chip consumes 5 amps.

When the 90 watt peltier is installed the relays for the fridge (it has a thermostat in it) click continuously and will not fire up the fans or peltier. When the lower wattage chips are in the fridge starts up fine. So, obviously the 90 watts is drawing more than the fridges thermostat circuitry can supply. Here's where I get lost: Now, do I need to increase voltage or amperage or wattage, or replace a component on the circuit board?

I prefer having the thermostat as it switches the unit on and off thus somewhat increasing efficiency. Also the built in system is much more elegant than anything I can come up with.

Hooking the cooling fan, peltier and circulating fan directly to the psu everything works fine, but runs continuously.

I suppose I can also remove all headaches by buying the correct chip which are under $10, but I am trying to work with parts on hand.

Any insights or suggestions are greatly appreciated.

--dES