HVAC controller

[gillecaluim]

I'm new to programming the PLC
I'm trying to design a zoned HVAC system controller for a dual stage heat pump.
Most of the ladder logic is working but I'm trying to get a few extra features
After a heating/cooling call is finished, I'd like to keep the fan running and damper open for a set period of time to flush the conditioned air out of the system.
so, what is the most efficient way to create a limited time pulse width on the falling edge of a relay coil so that when the heating/cooling call is finished the fan runs a little longer?

[gillecaluim]

never mind, found a demo that solved the situation.
using a latch & timer circuit  

[garysdickinson]

I know that you found an answer.  

I'd already worked up an example of how I handle this issue.  So I thought that I might as well post it.

Best regards,

Gary D*ckinson