A/C leak Evaporator removal

[bacon]

I am trying to find a leak in my A/C system. I have used the UV dye but not found any leaks in the engine bay. I want to check the evaporator under the dash but I cannot get either of the upper or lower black plastic covers off the evaporator. I have removed all the screws I can see and the clips that hold the upper and lower covers together. They are loose, but they won’t come out. What am I missing? Are they held in place from the engine side of the firewall?

[jagalfaowner]

I used a really good lead detector on the Defrost vent near the window. Does it go off? Easier test. I found my primary leak at the joining tubes in front of the condenser. Easier fix.