I'm trying to get the $2000 tax credit for my heat pumps but it's only giving me $600. It's supposed to be 30% up to $2000. How do I correct this?

The correct credit is $600 if you spent $2,000.  It is not a dollar-for-dollar credit.  The credit is 30% of your cost, to a maximum of $2,000.  So, in order to be eligible for the maximum of $2,000, you'd need to have spent $6,667 or more.

See this article for a summary of the amounts available: Energy Efficient Home Improvement Credit (EEHIC)