As you have asked about the address of the Mountain and 4th Branch of JP Morgan Chase Bank in Ontario, Canada, I am giving you information about it
Mountain and 4th
1070 N Mountain Ave
Ontario, CA 91762
909-983-6135

Branch Hours
Lobby
Mon 9:00 - 6:00
Tue 9:00 - 6:00
Wed 9:00 - 6:00
Thu 9:00 - 6:00
Fri 9:00 - 6:00
Sat 9:00 - 4:00
Sun Closed

Branch Services
Express Banking
Instant Debit Card Replacement

ATM Services
Drive-up
Deposit ATM
Deposit Friendly
Audio Assisted ATM

You can also use the locator option to get the details
Go to Chase Bank Canada website
Click on Locator, the page open look like


Here enter the required details and you will get the information.