Modern refrigerators are vast improvements over those of the distant past. However, in their effort to maximize interior volume, manufacturers have created another problem - the closely spaced condenser coils provide little access for cleaning. And that assumes you are lucky enough to have a model that provides a front access panel. Many models don't even have this feature, requiring that the refrigerator be emptied and moved to gain access to the coils for cleaning. And they do need cleaning as shown in figure 1. The dust buildup blocks airflow as well as insulates which decreases the efficiency of the unit, lowers its performance and increases its operating cost. Note that my refrigerator has a diagonal connecting tube in front which blocks access by conventional vacuum attachments. (Thanks Amana, I really do appreciate that design decision.) Some people just vacuum the front of the coils, but this does nothing to address all the dust that extends several feet to the back. Other people use special cleaning brushes that are made for this task, but these products don't remove the dust. They merely loosen it, making a nice mess which has to be contained and cleaned up.
Figure 1: Dirty refrigerator coils.
There are commercial vacuum attachments such as the SCG Wonder Wand, but this is 3/4" thick and I required something no more than 1/2" thick. I am also aware of the "Get Organized! Dryer Vent Vac" which is available at Amazon as well as on Ebay. However, people have complained that the rubber hose of the Dryer Vent Vac tends to have creases and kink. Lastly, there is the RepairClinic.com Vacuum Cleaner Attachment For Condenser And Dryer Cleaning, which they tell me is between 1/4" and 1/2" thick. This looks like a pretty good design, but the large open area at the end might not allow you to clean all the way to the end of the tip. So, I decided to build my own. It took me awhile to find a suitable tube with a rectangular cross section. At my local building supply store, I noticed a 5 foot long, 1 1/4" wide, and 7/16" thick plastic channel used to cover on-wall wiring, Wiremold model NMW1 (available at Amazon). This plastic channel, a 1" PVC pipe end cap (note that a 1" PVC pipe is actually 1.315" in outside diameter) and a tapered shop vac nozzle (that fits a 1 1/4" shop vac hose) is all that is needed (figure 2).
Figure 2: Parts needed - a 1in PVC pipe end cap, tapered shop vac nozzle and plastic cable channel.
The plastic channel consists of two halves that snap together. Perhaps a small amount of vacuum leakage will result from this design, but not enough to affect performance. I did not cut the channel shorter in case I ever want to use it for other tasks that require greater reach such as cleaning under beds. However, something this long can be awkward to handle, requiring frequent repositioning of the vacuum cleaner and/or a longer hose length when the nozzle is fully backed out away from the refrigerator. Also, remember that you will need an open space at least as long as the channel in front of the refrigerator. The added length did not seem to adversely affect the flow rate, at least not in my case. Understand that an attachment with this small of a cross sectional area will require patience to use and several "scanning" passes as it cleans only about a 1" wide strip at a time.
It may be acceptable to use the end of the channel as-is. However, I wanted a 90 degree downturn so that the suction will be directly against the coils. I cut the end of the "top" ("outer") channel half as shown in figure 3, where the "bottom" ("inner") half of the channel is facing the camera.
Figure 3: Cutting the end of the plastic channel.
I then used a hot air source (actually a plastic welder, but any small, directed heat source that can melt plastic should do) to soften the plastic flap where it meets the rest of the outer channel half to allow me to bend it 90 degrees with a pair of pliers. I held it in place until it cooled locking it in place (figure 4). The flap end should be beveled and filed down so that it is no higher than the other (inner) channel half to reduce the chance of it snagging like a hook onto the coils. Note the little opening on the right side. This provides for some "sideways" suction allowing the user to clean with it in the vertical orientation such as for cleaning the very narrow strip of floor between the side of a refrigerator and the wall. The same type of gap could have been placed on the left as well making it bidirectional, but this will reduce the suction available to the other two active sides. Perhaps an alternate approach to forming the end would be to totally close the end with something such as silicone sealer and opening up a bottom slot with a Dremel tool.
Figure 4: Forming the end of the plastic channel.
The suction gap is set by sliding one channel half relative to the other (compare figure 3 to figure 4). A rough rule of thumb is that the gap should be about equal to the inner height of the channel (about 1/4" as in figure 3). Figure 4 definitely has too much of a gap. It was only temporarily opened this far to protect the plastic of the other channel half from the heat used to soften and bend the flap. Too little of a gap will reduce the suction area and increases the chances that the end will clog, too much and the strength of the suction per unit area will be reduced, decreasing the ability to pull dust off a given area of the coils. There is another issue. Because the two halves of the channel can move relative to one another, bending the channel (which may be needed during cleaning) will result in changes to the gap. This can be prevented by gluing the two halves together, but doing so will result in a stiffer channel which will not be so easy to bend. Furthermore, the two halves of an unglued end can be later taken apart allowing the gap to be increased by cutting and shortening the inner half of the channel. I decided to leave the end of the channel unglued.
After you set the gap, cut about an inch long piece off the other end of the channel to ensure that both halves are flush with each other on that end. Clean off any burrs with a razor blade to prevent dust from snagging and causing clogs. I then used a Dremel tool with a cutter to open a slot in the PVC end cap that will accept the channel (figure 5).
Figure 5: Cutting a slot in the PVC end cap.
Take your time doing this as you want a snug fit with as little a gap as possible. When you are happy with the fit, apply PVC glue to the inside of the slot and to the outside of the flush end of the channel and quickly fit them together to solvent weld them. Don't insert the channel end further than is needed - just until all sides are fully within the inside of the PVC end cap. Don't allow the two halves to move relative to each other or else the end gap will change. If your channel plastic is not PVC or ABS, you may have to use something else for glue such as silicone sealer. Be sure to check for and remove any stray glue that is in the inner channel as that will impend flow and lead to clogs.
After the glue dries, cut off the tapered end of the shop vac nozzle so that it snugly fits into the PVC end cap as shown in figure 6. It is best to make several cuts to gradually bring it to size so that you can check for proper fit. If you don't cut enough, the fit will be too loose and the nozzle will bottom in the PVC cap before getting snug. Cut off a little too much, and the nozzle will not fit at all.
Figure 6: The hose end of the vacuum attachment..
Now, you can attach your vacuum hose to the nozzle and you're ready to go. Start at the top of the top coil with the suction end down. Make "scanning" passes until the entire side of the coil has been cleaned. Then, do the bottom side of the same coil with the suction end facing up, thus cleaning both sides of the same coil. Repeat for all the other coils. The result in my case was the nice clean coils shown in figure 7. And yes, they are clean like that all the way to the back.
Figure 7: Refrigerator coils after cleaning.