The Ice Cave! - S5.E41

Ash and friends enter an ice cave as it's a shortcut to Blackthorn City. After a watery run-in with Team Rocket, Brock catches a cold and the gang finds a Pokémon Center in the cave. While a Jynx working there is taking care of Brock, Nurse Joy tells Ash and Misty that the cave is cold because of a big building working there as a refrigerator. Team Rocket finds the building and they cause trouble by reversing the structure, heating the cave and cooling the jungle outside, and make their attempt to steal the Ice-type Pokémon as well.