Configuration/Communication Diagnostic Codes; Configuration/Communication Diagnostic Codes 27 & 43 - Friedrich VRP12K Service And Parts Manual

Configuration/Communication Diagnostic Codes

The FMC, MCS, Heater Board (HB), Wall Controller and Indoor Fan all communicate via ribbon cables. If
communication is lost or dropped, the VRP will not operate. These codes will also populate when there is a
software, firmware, or logic failure.
Configuration/Communication Diagnostic Codes 27 & 43
Check HB and MCS ribbon cable connection to FMC. Is the HB light on?
If HB light is on, the cable is more than likely working
correctly. If the light is not on, it could be a
malfunctioned HB or cable.
170
TROUBLESHOOTING
IDF Cable
Verify the ribbon cable is fully inserted in the FMC
and MCS. If all checks pass, there may be an
issue with software. Replace MCS and FMC SD
card.
HB Ribbon
Wall Controller Port
MCS Ribbon