Your refrigerator is one of the hardest working appliances in your house. It's always running; day and night, summer and winter, rain or shine. Other than a hot water heater or a well pump (if you have one), your fridge works harder than just about any other machine.
Yet refrigerators run incredibly reliably despite this. Minding their manners they just keep humming along in our kitchens, keeping our food and drinks cold and safe. In fact they work so good that we often take them for granted... until they stop working.
The most common culprit of refrigerator malfunction is the compressor or one of the parts associated with it, such as the relay or regulator.
But before we go any further, I would like to warn any DIY handyman or woman: replacing a compressor isn't for the faint of heart. It's expensive, complicated and can even be dangerous. In most instances you might be better off hiring a professional refrigerator repair service even if it means spending a few extra dollars. But if you're determined to do this yourself, read on.
How To Tell If The Compressor Is Bad
If the unit seems to be stuttering, running for short amounts of time then shutting off then turning right back on (or at least trying to), you're dealing with a condition known as "short cycling." Short cycling can repeat itself every few seconds or every few minutes, depending on the appliance itself.
You'll need an ohmmeter for the rest of this (if you don't have one of your own you can buy the one I use at Amazon for about $19).
You'll also need to take responsibility for what you're about to do. While I've worked on appliances myself for years and can honestly say they're easier than most people think, there is an element of risk involved anytime you take on a do-it-yourself job - be it to yourself (physical harm or death, we are dealing with electricity and chemicals here) or to the refrigerator or other personal property. If you're unsure, hire a professional.
Okay, let's get started:
Pull the relay and overload off the compressor. The compressor has three prongs that these to "sit" on (the overload protector is sandwiched between the compressor and the relay). They should come off without the need for hand tools, but if they are stuck you can usually coax them with a little loving leverage from a flathead screwdriver, just be careful not to bend or break the prongs.
Test the resistance between all three prongs. Use the ohmmeter for this. Mark the two that read the highest resistance. The other one is called the "common," and it's connected to the starting windings and the running windings.
Test the reading from the common to the other two prongs and record the reading. Then add them up.
Test again the reading from the two non-common prongs. Record this reading as well. In a perfect world the resistance from the two non-common prongs should equal the combined readings of the common to the others individually. If they aren't within about a half ohm of each other, it means one of the windings has shorted. The result is that it will run hot (if it runs at all) and the overload protector will kick in and shut everything down.
Your only option here is to replace the compressor unit. But be advised that this is a major undertaking and not for the faint of heart. Unless you have experience working with refrigeration and electronics, I'd highly suggest either finding a professional to do this for you, or even buying a new fridge.
Seriously. The cost of fixing a compressor is higher than most people expect, and in most circumstances it actually makes more sense (financial and otherwise) just to buy a brand new refrigerator. Or if money is tight, check out: Scratch and Dent Refrigerators.
Where To Buy Replacement Refrigerator Compressors
You're probably not going to find these at your local home improvement store, you're going to need to special order these parts. Sometimes you can order them directly from the manufacturer, other times you can find better deals by purchasing through an appliance repair store (yes, most will be glad to sell you parts as a DIYer).
You'll need the make and model number of your fridge, as well as any special identification numbers that may be on the back plate. If possible bring your worn out compressor in to make sure you're getting the right part.
Also be aware that you'll probably be waiting for the parts to come in. Rarely are these in kinds of parts readily in stock unless you have a fairly new fridge (in that case, it might be covered under a warranty anyway).
How To Replace A Refrigerator Compressor
Again, let me reiterate that this is a serious job. It requires advanced skills in refrigeration, specialty freon recovery equipment and even welding supplies and experience. This is by no means a job for a handyman. The people who replace compressors for a living have been trained specifically for this job under the supervision of extremely experienced professionals.
I know it's hard to for most DIY folks to hear, but this isn't something you can "wing" simply by reading a book or watching a YouTube video. You either have the experience to do this job or you don't; it's really as simple as that. As much as I'd love to say that this is like building a deck, it's not. Doing one step even remotely incorrect could result in death. Yes, I said death. You could literally die doing this job. Not only are you dealing with extremely deadly chemicals (Freon), these chemicals are under extreme pressure. Furthermore, the parts themselves must be aligned and sealed properly; something as indiscrete as a slightly incorrect torque could cause injury to oneself or property.
So my advice to you, should you want to go forward and actually replace a fridge compressor yourself, is to sign up for a course at your local trade school or community college. I'm not being a wise guy, I'm being 100 percent serious. The scope of a job like this is far too intensive to list out here. Or stop in and talk with a repairman at your local appliance repair shop. They might even let you shadow them for a while and ask questions about a refrigerator compressor replacement job.