Yes,
You may convert non-deductible IRA assets.
However, it is important to note that you cannot designate any part of the converted amount as attributable to the non-deductible portion, unless you file IRS form 8606, which will provide you with this information…according to the IRS, for purposes of determining the taxable portion of your IRA distribution ( or conversion), when you make non-deductible contributions, all your IRA balances are treated as one IRA. All these balances must be used in the computation, For example.
IRA balance 1= $10,000 (deductible)
IRA balance 2=$2,000 (non-deductible)
You convert $1,000 from IRA balance #2. To determine the taxable portion of the $1,000, you must combine the balances of both IRAs. The taxable portion may be $900 (approximately). Use this form to make the exact determination. The link the instructions are also provided
http://ftp.fedworld.gov/pub/irs-pdf/f8606.pdf
http://ftp.fedworld.gov/pub/irs-pdf/i8606.pdf