Hmmm, something doesn't seem right.

The lower value pull-up, and pause 750 shouldn't be needed.
The OWIn DQ, 4, [count_remain] will check the busy bit until the conversion is complete.

..... Unless it's running on "Parasite Power". In which case you need a Strong Pull-up on DQ during the conversion, and you can't read from the device for 750ms.

If that fixed your problem, then you probably don't have 5V on pin 3 of the 1820.
And if "Parasite Power" was intentional, you may need to do things differently.
<br>