Sheets in a ball!

This is the dryer working correctly on a load shaped wrong. A king fitted sheet acts like a sack: whatever else is in the drum gets wrapped inside it, the outside dries into a shell, and the middle stays damp. The moisture sensor reads the dry shell and ends the cycle early.

Cheapest first:

1. Dry the sheets alone, nothing else in the drum, and put them in loose instead of bunched.

2. Interrupt the cycle at 15 to 20 minutes, pull the bundle out, shake it open, put it back. One interruption usually saves more time than a longer cycle.

3. Sensor dry on medium heat, not high heat on timed. High heat sets the outer layer hard and bakes the fold wrinkles in.

4. Two or three wool dryer balls keep the layers from sealing against each other. Softener sheets do not fix this.

5. Clean the lint screen every load and watch the outside vent flap while it runs. It should swing open fully. A restricted vent dries the shell faster than the core and makes balling worse.

6. On a sensor dryer, wipe the two metal sensor bars inside the drum front with a damp cloth and white vinegar. A lint film on them makes the dryer read the load wrong.

7. Shake the sheet out before it goes in and keep the load small. A king sheet alone wants maybe a third of the drum, free to tumble.

If it still balls up with a small load and a clear vent, check that every drum paddle inside is still there and that the drum turns smoothly with weight in it. Worn rear rollers or glides let the drum slip instead of tumbling the load.