Panasonic Urban Multi MX1R Series Service Manual page 618

PACD011001C2
R22 model
1. When R22 indoor unit is connected to HFC (R407C) system
connection
abnormalities
Reason : Operation disallowed due to insufficient pressure proof in R22 indoor unit.
2. When HFC indoor unit is connected to R22 system
Reason : Operation disallowed to prevent contamination of another system by HFC indoor unit operated
previously with R22 system. If HFC indoor unit that was operated with R22 system is removed and
connected to another HFC system, it can contaminate (SUNISO oil etc.) the newly connected HFC system.
Appendix
Typical Wiring Mistakes
597