To unclog a coffee maker you can run vinegar and water through the coffee maker.
Start by removing and coffee grounds and residue from the coffee maker.
Then mix equal parts of water and equal parts of distilled white vinegar.
Next pour the vinegar and water into the coffee maker's reservoir where you put the water normally.
Then run the coffee maker through it's normal brewing cycle like you would when making coffee.
If your coffee maker has a cleaning cycle, then you can use the cleaning cycle but if not the brewing cycle works.
Allow the vinegar and water to go through the coffee maker and then shut the coffee maker off and allow it to cool down.
After the coffee maker has cooled down, dump the vinegar and water out and then pour straight water into the water reservoir.
Then turn the coffee maker back on and run it through another brew cycle to remove the vinegar.
You may have to run the coffee maker a few times to get all the vinegar taste out.
You can also buy coffee maker descale solutions but vinegar works just as good and is cheaper.
To keep your coffee maker in good working order it's best to run vinegar and water through it to descale it at least every few months or so.