I am running my heat pump for heat and I'm having a problem with air temperature coming out of air handler. While observing and trying to understand why the liquid line at the air handler would grow cool after unit was running for about a minute and the slowly start to warm up again I went outside and watched the suction line accumulator frost up and become ice cold. The compressor would also feel cool to the touch especially at where the accumulator line was coming in. Tech coming out today to look at it. What are some of the possibilities he should see.