Twenty years ago, we could break down all areas of HVAC diagnostics into three categories when you really think about it. It was and still is called Heating, Ventilation, and Air Conditioning (HVAC). All of the HVAC parts and components did the same thing NO MATTER what vehicle they were installed on. A compressor pumps, the TXV valve meters, the heat-exchangers allow a change of state, etc.
Even if the car had Automatic Climate Control, we still needed to determine some basic operating characteristics before going deep into system diagnostics. I’ll spare the customer confirmation and validation of the problem speech for this writing. Let’s just say, something in the HVAC is broken and we know it’s broken! By the way, while we’re talking about validation of the customer’s concern, let’s get the ugly word “Intermittent” out of the way. I was taught a very long time ago by a GM instructor that there is NO SUCH THING as an Intermittent. We just haven’t duplicated the conditions necessary for the problem to replicate itself. Read the entire story