Just got down to 18 last night where im camped in my 2018 cyclone. Furnace ran all night so should have been warm air in underbelly. Also ran the yeti pack and line warmer all night but still had froze up kitchen faucet and rear bath and toilet. Front bath had water and water pump would run. Its thawed now but wondering if any of you experiened this and what have you done to remedy? Do i need to tear into the dreaded underbelly?