Fault codes covered
28-71
This code will be set if fuse 1 is blown or missing on PCM board. Fuse 1 Powers RVS, PEV (if present). When fuse 1 is open none of these components will function.
AC units will operate if pressure differential is below the maximum allowable starting threshold (100psi), but HP units will not operate at all. The code will clear once short is removed and fuse is replaced with new, undamaged part. If fuse is blown there is a likely short in either the PEV or RVS harnesses. If no physical damage is observed, begin by unplugging all components from PCM and make connections until replacement fuse opens. Harness should be repaired before replacing fuse. See wiring diagram for fuse size and location
Source: ACHPVSR454-02SM troubleshooting pages.