Okay guys I stumbled across this site through a google search and am hoping someone can help me. I have an old Coleman A-Coil and outside unit that came from a mobile home that I am trying to set up in a workshop. The outside unit is model number BRCQ0361BD and the A-coil from what I have read is matching with model number MBC36CQD. I had a guy come out and look at it and he told me that the orifice piston is missing, but he had no idea what size it would need. I have searched the internet all morning but have had no luck locating any information on piston size. I found a couple of complete manuals with all kinds of information, but nothing about the piston size. What I am wondering is if there is some way to take some of the information that I have found and calculate what the piston size must be, or would this be information that I could only find out from the mannufacturer? Thanks for your help in advance.