The Thermodynamic Concept Survey is a multiple-choice test used in the Physics Education Research community. Analyzing this survey, we detected two issues that made it difficult to evaluate students' understanding on the survey's topics: (1) numerous items present only responses of the type: "increase", "decrease" or "remains unchanged" without including the reasoning that led to these answers, and (2) several questions have design problems. Considering these two issues, we decided to undertake a research project with the objective of modifying and refining this survey. In this article, we present preliminary results of this ongoing investigation regarding those two issues. In the first part, we illustrate the modifications made in some items, describing the modifications made in four of them. In the second part, we illustrate critical design problems in some items, describing in detail a problem in one of them. The results and discussion may be useful for researchers using the test as an assessment tool.