All fuses power good, the control board checks L1 and L2 have power(115 volts)door switch is working. Fan will not run in manual position and a/c will not turn on. Older currier unit new control panel and working thermostat fan runs while heater is being used with no problem but fan will not run in the "manual on" position nor will the A/C turn on from thermostat. I had a new thermostat placed with correct wiring and it still will do what was described about so I put old switch back on and still does as described.please help

Has the system ever worked correctly? Sounds like you need to have a hvac tech out to check the system.

This look like issue with the main board look if you get any error message on a LED also if you switch to manual see if you have any click coming from the relay on the board am strongly believe that you have to replace the board
john (http://www.njairconditioningrepairservice.com/)

Wow, really? You suggest replacing one of the most expensive components first? That is simply a bad diagnosis. Without being able to really know what is happening with the unit, you should niot suggest such extreme measures.