Upon my arrival in Lockhart I spoke with the customer about what was going to be performed in the heating evaluation today. I started by checking the emergency heat strips and found them operating properly. I the started to perform the evaluation to check the heat pump operations and going the system kept shutting off due to low pressure. I checked the reversing valve and made sure it was not stuck. Once I verified it was good I then checked out previous repair to verify it was not leaking. While I was checking the previous repair I found that the heat transfer media coil has a leak. I spoke with the customer about their different options for repair and they chose to go with HL1C. Customer is going to try and not run the system until we can return for the repair, they still have the downstairs system to keep them cooling.