I have owned Coleman and Igloo 12v coolers and have never had a problem with either one cooling quite well.

I do not know where you have yours set up at, or exactly how you are using it but here are some tips/info:

If the items are warm or only slightly cool when you put them in your cooler, and if the cooler is shut off or has only been recently plugged in it can take 12+ hours to really cool those items down.

To get the best cooling the cooler should be kept out of direct sunlight and there needs to be at least `1 inch of air flow around it. Also make sure that there is not any heater ducts blowing on it. Remember that these 12v coolers will only cool 35-40 degrees below what it percieves as the surrounding air temp.

To help them cool faster and to stay cool longer when you unplug it and to be a bit colder when in use put a small (20 oz) bottle of water or use two or three ziplock sandwich bags, one inside the other, and fill with ice. I suggest the latter if you are on the road for more than a week at a time as you can refill the baggy.

I have actually frozen water in them several times.

another trick you can do-- if you want to make your therm-electric a freezer for a while is-- buy a bag of dry ice put in top--- it will drop the temp inside down to -30 degrees for 3-4 days. Best part is; the dry ice becomes co2- not water so it won't damage your cooler like ice would if the bag was ripped open-- you also can take one of those inside/outside digital ICE Warning therometers and run the wired prob down inside the cooler and have a current digital temp readout all the time. This way you will know When it's time to plug the cooler in. Not a good idea to run the cooler with the dry ice at sametime-- the air-flow makes your dry ice sublime faster.

i have on of the roadpro coolers with the glass door and it will freeze my drinks im mean solid ice other than that i love it had it about 6 months paid like 70 bucks for it

Dry ice is really not a good idea to use in a cooler. It is toxic if ingested, also in a small enclosed area, such as a truck sleeper, the potential for creating high levels of carbon dioxide is there, which can be fatal or at the very least cause serious respiratory problems.

did it for years... works great.. you just have to be smart and not touch it with bare hands( unless you want to burn yourself/ cut the skin off with a razor) and you have to be intelligent enough not to stick you head down in the cooler and inhale deeply. Yes, dry ice does displace O2- this is why you don't stick your head in the cooler. We're only talking about a single bag of dry ice... not a truck load.