A few weeks ago a tech came out to check everything on my Ruud heat pump as a preventative and he said all was well. Now that I'm using the heat I have noticed a problem. When the unit comes on the liquid line starts warm then in about a minutes time you can hear what sounds like a vibration and the liquid line becomes cool. The temp exiting the air handler mirrors the drop in temp, then the temperature starts rebounding slowly to what it first was and the liquid line warms up as well. For example, unit comes on to 95 degrees exiting handler, one minute passes, liquid line grows colder, temp from handler drops 6 to 7 degrees, vibration noise goes away, temp starts increasing a degree each minute, temp reaches 95 degrees again, temp continues to increase depending on outside temp. Can anyone explain what is taking place here?