Temperature logs are ad-hoc - you can record them whenever you need to, without a task being assigned.
Fridges and freezers are set up on the web app first. If you're a Site or Organisation Admin, go to Inventory on the web and add them. If you're a staff member, ask your manager.
On the mobile app: tap + then Add Log, choose the log type, then tap the orange records button in the top right corner and select the log you'd like to view.
On the web app: go to Temperature Logs in the left sidebar. Select the log type and date range. You can also Export logs from here, which is handy for EHO visits.
Tip: admins can also set up a daily reminder task such as 'Fridges & Freezers AM' so temps are never missed - see Do I need a task to record temperature logs?