Hi Rich1,
The wires that should be jumped are on the cycling switch. This is the switch that controls when the compressor engages and disengages.

Near the firewall, right at the eveaporator outlet, there should be an aluminum can (about 3" diameter) It may have a charge port on it, but it should also have the cycling switch. Remove the plug and jump those wires. That should engage the compressor.

The reason for doing this is so that the compressor suction will pull the refrigerant into the system.

Hope this helps! If you need more help, just let me know or pop in to our forum. There's pros with all the answers!

Typically, the compressor will not come on unless there is a certain amount of pressure in the system. Rich1 indicated that he replaced the compressor. Therefore, he started from an empty system. The first part of the charge would go in quickly because the system is empty (and it should be charged into a vacuum). When pressures equalize, there is no long a natural flow (from the higher pressure in the can to the lower pressure in the system). Therefore, you have to 'jump' the compressor to make it come on.

In your case IlikeCARS, it sounds like you were just low. There was obvoiusly enough pressure in the system to 'tell' the compressor to come on. Therefore, adding refrigerant went quickly because the compressor 'created' a lower pressure (on the suction side of the system) and the refrigerant just flowed.

Hope this helps and explains it!