My compressor locked up last fall an I'm just getting around to repairing the system. I've read I can't flush through an expansion valve so I'd like to disconnect the rear valve, flush the long lines from front to rear and replace with a new valve. The rear expansion valve is in tight in the rear fender area. How do the lines come off the bottom of the valve? I see no screws or clips. It has a large, brown, plastic ring around both of the lines coming up from the bottom but no visible screws. The new valve has no threaded holes.