The importance of selecting the right replacement component during a repair cannot be overemphasized. Choosing the wrong replacement can cause a system to operate improperly or lead to future failures and/or service issues.

When replacing a component, it is generally best practice to obtain its replacement by referencing its part number and installing a component with the same part number. Unfortunately, this is not always possible or practical. Due to the nature of the systems we service, many times we are forced to select a replacement component based on either a cross-reference or by matching its specifications to those of the original component.

Let’s say a walk-in freezer is down. The freezer is full of product, and the failed component is not in stock. In situations like this, it might be very tempting to consider a replacement part offered by the wholesaler. However, it’s extremely important that you make sure the replacement matches the specifications of the original component. Sometimes there is room for minor differences, but generally, that’s not the case.

What may seem to be an acceptable component may not be right. For example, you need to replace a thermostatic expansion valve (TXV) and are given or select a valve that physically looks the same, mounts the same, and has the same Btu capacity. However, its power element is different from the original. Depending on the difference, this may cause you some issues, and you may not be able to control the evaporator’s superheat value correctly. It may even cause the system to floodback to the compressor. 

Or, let’s suppose you are changing out a compressor on a capillary tube system, and when you go to change the filter drier, you do not have the exact replacement but you do have a larger one. You decide to use it, thinking, “bigger is better,” and, “How could a larger filter drier cause an issue for the system?” Well, it can. The larger filter drier will likely cause you to add more refrigerant than was originally used. That could cause liquid to floodback to the compressor and cause your replacement compressor to fail prematurely.

Perhaps you need to change the potential relay and start capacitor on a cooler. You are able to get the original potential relay. The original start capacitor is not available, but there is a replacement start capacitor available that matches its microfarad and voltage values. So far, so good; this should not be an issue, right? Wrong. You overlook the fact that the replacement start capacitor does not have a bleed resistor. After you install these components, everything seems to work great, and you go on your way. However, a few months later, you are back at the system and find the start relay failed. You cannot explain why the new relay lasted only a few months until you realize the start capacitor did not have a bleed resistor, which was the cause of the potential relay failing. 

So, the next time you use a replacement component, make sure it is the right component. If using a non-OEM component, verify that it very closely matches the specifications of the original component.   

Publication date: 5/1/2017

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