These letters are notices about your refund check. In Notice CP32 they tell you they have sent you a new refund check. More information about this notice can be found here. They also send Notice CP31 if the refund check was returned as undeliverable.
Respond to Notice CP32
Notice CP32A requests that you call the IRS to request your refund check. Usually, the original refund check was returned as undeliverable by the US Postal Service. Often, the IRS has your wrong address. The last return you filed is supposed to update your address with the IRS. But, if there is any question, you can always file a Form 8822 to officially change your address with the IRS.