Discretionary sending in the ACA would not be spent, but the individual mandate and other mandatory spending would be unaffected.
Discretionary funding may be affected by defunding the ACA. This amounts to $100 billion over the next 10 years.
The Congressional Budget Office (CBO) estimated that ACA’s discretionary spending provisions, if fully funded by future appropriations acts, would result in appropriations of almost $100 billion over the period FY2012-FY2021.11 However, much of that funding—about $85 billion—would be for three programs that were in existence prior to, and whose funding was reauthorized by, ACA; namely, the National Health Service Corps, the federal health centers program, and the Indian Health Service (IHS). --Discretionary Spending in the Patient Protection and Affordable Care Act (ACA) (pg. 7)
Mandatory funding would be unaffected by defunding the ACA. Subsidies for individuals and families on the health exchanges would be unaffected.
Health insurance exchange grants. Appropriates annually an amount (as determined by the Secretary) necessary to award exchange planning and establishment grants to states. No grants may be awarded after January 1, 2015, by which time exchanges must be self-sustaining. [CMS/CCIIO; CFDA 93.525] --(Appropriations and Fund Transfers in the Patient Protection and Affordable Care Act (ACA) (pg. 12))
Laws that do not concern funding would be unaffected by defunding of the ACA. If you break laws defined in sections of the ACA related to individuals or businesses, you would be subject to the fines or penalties there in.