I'm looking for answers from someone who knows their stuff, please don't hijack this thread! So, my mother-in-law's HVAC system has been on the fritz, it's a heat pump unit for the 1st floor in her house. SYMPTOMS: It's been tripping the circuit breaker a lot for this heat pump unit. It's not heating unless we have it switched to EMERGENCY HEAT, and that's the ONLY way that it's heating. Plus, when it was warm recently the AC didn't cool the house down (it was 80+ just a few days ago). So, she's got a home warranty and she called and the tech came in from a company that we'll call "FFF Air Conditioning & Heating" and he looked at the system and said that there was a shorted out wire on the secondary heating unit, so he fixed that up and now that was working and all is good. When he was here it was one of these rare days where it was 25F outside, so that makes it difficult to really test it from my perspective. QUESTIONS: No matter what, shouldn't the system work as a whole so that we never have to flip on emergency heat, unless we know that a problem exists with the primary heat pump? (again, PLEASE do not answer this unless you are qualified to answer.) The tech said that we should be running on Emergency Heat, mostly because we have an old mercury thermostat and it was 25F outside. However, this system used to work without having to do this, so why should we start now? If the thermostat isn't working properly, then they need to replace it! There are more questions to ask, but I would prefer to PM someone directly who has the answers. THANK YOU! - - - Updated - - - Wow, maybe I should open this up to more people. Lol. The first floor heat pump is not working, the heat pump in the 2nd floor is working fine and we can get the temp up to over 75F and downstairs it's in the 50's or 60s F. The guy was not exactly the smartest tool in the shed ... ugh.