I have a 1981 300SD, trying to put the a/c system in working order. The system has been down for 1 year. I have purchased a used R-4 compressor, used condensor, a new receiver dryer and a new expansion valve.
Is there anything else that I would need to replace while I'm in the process? I also plan to use a R-134 retro fit kit. Would I have to use a different kind of compressor and receiver dryer and expansion valve to complete this R-134 retro fit? And lastly where is the expansion valve located at? I want to take out the old one and replace it w/ a new one. Would you be able to provide me a step by step instructions to get to the expansion valve and how to remove it.

Thank you

GP