Is charcoal or the smoker at fault for low temperature smoking?

It's the smoker. I had one of these, and it is extremely flawed in design. The pan that holds the charcoal does not allow for proper air flow to the fuel. Contrast this with a Weber grill, where you put your fuel on an elevated grate with plenty of air beneath it. This Char Broil instead just has a pan that you put on a shelf. Before long your coals are buried in ash, and barely smoldering. FWIW, if you were to attempt sealing the doors, it would only exacerbate your problem, as the issue is with not enough air, versus too much. I replaced my Char Broil with a Weber Smokey Mountain, but I had considered some hacks to make it better. Your best bet would be to ditch the pan-on-shelf system, and fashion your own charcoal grate that is elevated from the bottom of the smoker. You want something that will both allow air flow to the fuel and allow the ashes to fall away from the fuel. Then you would be able to properly manage temperatures with the air vents.

I've got a very similar model smoker.

Some things to consider:

• Ignore the temp gauge on the front. Buy an oven thermometer or a probe thermometer with multiple probe jacks and mount one on your grate. The front therm is placed in such a way that it won't ever read the grate temp, even if it was calibrated properly (it probably isn't).

• As the other answer says, ditch the charcoal bowl. As far as I can tell, the main reason for the charcoal bowl is to keep embers from settling on the bottom and reducing the life of your smoker by making holes in the bottom. Besides the fact that bottom of your smoker isn't that important (holes there actually won't affect your smoking), this is a terrible idea. It's a double whammy for your cooking temps, first the charcoal at the bottom doesn't get any oxygen causing it to burn poorly or not at all, second the ash can't fall away causing the actual burning charcoal to not be able to access oxygen. What I've done is to buy an enameled grill pan from a big box store's grilling section, bent it in sort of a U shape (then bent the ends of that so it will hang on the shelf), and put my charcoal on this. It's got a lot of smallish holes that only small embers can fall through, but it lets the ash fall (and can be tapped to further this), and lets oxygen in through the bottom and sides.

• A lot of people will insulate their doors, but this can be challenging, expensive, and is a more involved solution that should be saved.

• If you don't mind more maintenance, you can always do without the water pan. The water pan does two things for you, it acts as a thermal reservoir so that opening the door has less impact, and as a heat deflector so that you can have a strong fire right below the meat. If you axe the water pan heat is much more direct so you have to be really careful about how much charcoal is burning, but there is enough space between the fire and the meat that if you only have a very small fire, the heat can be at least relatively even. The other option (and this is the one I'm considering actually), is to line the pan with foil, and then fill it with sand. This provides exactly the same benefit (and is a bit better at retaining the heat at higher temps), and doesn't evaporate. The drawback to sand is that it's better at retaining heat so if you bump your temps up too high, it can be hard to get them back down.

All that said, this is a poor quality smoker. It's a cheap one for a reason, and while it will do the job, it is more work than a lot of other options. I've had a much better experience smoking on my 18.5" Weber kettle (a slightly more expensive, but much more versatile option). However, with some work, you can turn out great food on your smoker. Keep practicing, keep learning, I know I still am.

Same issue here. Had to finish my ribs in the oven (although I did line a cookie sheet with foil :))even after pulling the charcoal pan and drilling holes and starting over. Ate through the coal and wood hunks (the wood hunks were all that would bring temp to 220 or so). I'll play with with this pos til it rusts out the. Get a decent smoker.