Articles by Joe Marchese

A thermostatic expansion valve (TXV) is designed to maintain a specific amount of superheat at the outlet of the evaporator. If the superheat value is too high or too low, the TXV may be the cause. However, before deciding the TXV is defective, all other system causes must first be investigated and ruled out.

Verifying a diagnosis will take additional time, but this is time well spent. It will actually save time and money for both the technician and the customer by reducing the amount of callbacks and reducing the replacement of non-defective components on the job. It will also allow the technician to leave the job with peace of mind, knowing he has made a correct diagnosis.

The correct placement and installation of the thermostatic expansion valve (TXV) sensing bulb is important to its overall performance and reliability. An incorrectly installed or placed sensing bulb can lead to several different types of system problems. Here are some general installation concerns and tips to follow when installing a TXV.

All of the components may be operational, but are they adjusted and working properly as a complete system? A professional installation will include a thorough inspection of the system as a complete unit.

The next time — and every time — you’re picking up a replacement part, make sure to take the time to verify that the part you need is the part you received. Always trust, but verify.