Hold on a minute. Something else is wrong or something is not wired properly. The ACW4 is pretty simply. It is only capable of stacking and holding one wash. How are multiple people losing money? There are basically three states the ACW has:
1) Waiting to take payment. When it does it will send the wash to the Petit.
2) Waiting to take payment and waiting on a CI input for the last wash it sent to the Petit so it knows the wash is ready. In this case, the ACW will hold the paid wash and display "please wait, car wash in use" indefinitely until the CI signal is received. Once it is received, it will release the wash to the Petit. The ACW will not take anymore payments in this state, the
coin mechs and validator are disabled.
3) The last state is where the ACW CI signal is constantly on. At first the display will say "Car Wash Busy", then after 10 minutes the display will change to "Car Wash Closed". Obviously in this state, the ACW will not take any payments.
(This is using the CI circuit in 'Passive' mode meaning the normal state of the relay is deenergized. To signal the input the relay has to have power applied. If you were using it in 'Active' mode the relay is energized all the time and to send the input signal, the power to the relay has to be dropped out.)
Only one person should be able to lose money...the person that is left sitting there indefinitely waiting for their wash. If they end up driving away and someone else pulls up the ACW won't accept any payment.