We are in the middle of a large ip camera install. Several runs cannot be rewired and have only rg59 and power. We are using Ethernet over coax baluns and they work great. However, one camera has rg59 spliced with cat5 and a balun. We tried the Ethernet over coax and it does not work. Any solutions for an ip camera in a case like this?

I assume the splice is not accessible? Otherwise you would have put the Ethernet over coax adapter there.

There are several Ethernet over 2 wire products out there. Doorbird just released one or at least announced it at CEDIA. Mobotix has one we have used. There are plenty of others. Most will do POE as well.

If you can access the splice, put one of the baby 5 port PoE powered network switches.
That will give you single cat solution for data and power for the switch and you'll have 1 PoE port out of the switch to power the RG59 converter.

We were able to find the splice in a junction box in the ceiling in the garage. The cat5 bringing the video back to the control room only has one available pair which is being used for video. We do not have the whole cat 5 available.

Do you think the doorbird 2-wire would work? It would be (rg59) to (coax to ethernet balun) to (doorbird balun) to 2 wires running back to the control room to (doorbird balun) to network switch.

It seems like a lot to go wrong!