My heat pumps are acting up, the living room unit runs but does not create any hot air and the rear unit has started making weird noises.  A couple nights ago it got down to 34 degrees F and I was running the rear unit with the fan set to run continuously at low speed.  After running fine for a number of hours the fan stopped but what sounded to me like the compressor kept running although it didn't sound quite right.  after about 3.5 minutes of this there was a loud air release sound, the compr