As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ALL THREE ZONE TEMPERATURE CONTROLLERS "HYPER - SENSITIVE" THE SLIGHTEST TEMP ADJUSTMENT (HOT OR COLD) RESULTS IN VERY LARGE TEMP SWINGS/SPIKES. HOT OR COLD. GROUNDED - YES. COULD NOT DUPLICATE DISCREPANCY BOTH TEMP CONT LOG NO FAULTS AND A GO STATUS. REF B737-800 AMM 21-61-00-700-806. ACCOMPLISHED CABIN TEMP CTL OPS TEST REF AMM 21-61-00-700-806 ALL OPS NORMAL.