4 year old dehumidifier does not ext...

It may have lost its charge of refrigerant. Check the warranty for sealed system, or if it is just the compressor which is covered. There are coils above the bucket area. Check for possible frost on only part of the coil. It is a sign that it has a leak at some point and has lost its refrigerant charge. If it lost all the gas there will be no frost nor condensation on the coils. Four years old and $75 bucks, its your choice.

We had the same problem with our Whirlpool dehumidifier. Had it looked at for $35 (Rhode Island). Were told the seals were no good, and this part was still under warrantee (5 yrs) though the unit was three years old. The repair store advised us to call Whirlpool. After we mailed them written proof that it was the seals, the company sent us a brand new one, and paid for us to ship the old one back to them. However, now we're having problems with the new one, after only two years. I'm debating whether to go through the same rigamarole again, or go out and buy another brand this time.