AC leak

Hey everyone
When we replaced the engine in my 2002, the ac lines were disconnected from the condensor. Since then, I cannot get the system to seal and keep a charge.

The only 2 lines disconnected were the 2 hoses at the top of the condensor. Then when I couldnt get that sealed and holding a charge I replaced the dryer/accumulator and the orings on the hoses there as well as the orings at the condensor.

So what gives? How do i get this to seal?

This is what I used on my Jeep YJ when I flushed everything then replaced the o-rings using this:
Refrigeration Technologies RT200R Nylog- Gasket/Thread Sealant (I found it on Amazon, so you can read about it there)
No problems since.

Also, you may want to check the valve cores on both high & low connection ports if you haven't already.
My YJ was converted to r134 and the valve cores were bad on both ports causing slight leaks.
Something else I will mention that you likely know...those o-rings are very easily pinched (as I quickly learned the hard way!).
I went back through all the connections and made sure the o-rings were the correct size too and put a generous amount of nylog on them all.

get UV dye in it to find the leak or a sniffer tool.

It could be the two flex hoses going in and out of the compressor.
There was a very tiny hole in mine when i last worked on my AC system (the AC shop I went to found it) on the low pressure side going from the evap to the compressor.

changing all the seals and schrader valves too would be a good idea.

Thanks for the tips everyone. What a pain in the neck. The frustrating part is that it worked great before my engine swap....

you can get a loaner vacuum pump from your LAPS as well to do a leak test.
Pull a vacuum in your system through a manifold and see if the vacuum holds.

Only issue with checking for leaks with a vacuum pump, you only apply around 14.7 PSI of pressure when doing so... The system can operate at well over 200psi.... So a leak may not show up under vacuum, but will under pressure.

Ive found leaks with the system under pressure. You can use nitrogen to pressurize the system then use soapy water to find leaks. Or just charge the system with R134a and use soapy water.