Thanks for watching this video in this video we're going to talk step by step through what it takes to replace an evaporator coil, unfortunately, in our trade, one of the realities is that evaporator coils leak quite a bit more than they should and there's many reasons why That can happen, you can get formicary corrosion or ant nest corrosion from the outside in the inside out, and you can also have some galvanic corrosion, especially in coastal environments. But the first step, when you are going to replace an evaporator coil, is to make sure that you know exactly where the leak is before you replace it, because they have been so prone to leak in so many markets and in so many different systems. A lot of times, technicians get so conditioned to condemning them that they don't diagnose the entire system. So not only confirm that you know that the evaporator coil is leaking and where it's leaking with a good quality leak.

Detector, like a heated, diode, electronic or maybe even an ultrasonic, but then also leak check the entire rest of the system. Before you proceed with replacing it to ensure that you're not going to be giving the customer a very expensive repair that won't actually fix the problem. So be very thorough in re-diagnosing, once you do that, then you want to go ahead and get the refrigerant out now, because it's an evaporative coil generally, you can pump the system down to at least some degree in many cases. Nowadays, when you have scroll compressors scroll compressors will actually stop pumping once the compression ratio gets too high, but some of them will still work.

Okay, you never want to pump a scroll compressor down into a vacuum or really any system, but you do want to pump it down to a low pressure. So that way you lose as little refrigerant as possible because, as you know, even when you take and put some into the recovery machine that last little bit that refrigerant can easily get mixed and contaminated. So you really want to keep as much of that clean refrigerant. In the system as possible for cost savings, so what you're going to do is you're going to take your valve caps off you're, going to use your service wrench and usually just use a little adapter on your service wrench or another hex key you're, going to close The liquid line down you're going to run the system and watch your pressures on both your suction and your liquid side, they're going to drop generally pretty quickly, often about 10 psi.

That's when you want to go ahead and shut off the disconnect and then also shut down the suction valve. At the same time, just in case, your compressor is leaking a little bit through the valves. You don't want that pressure to rise and that refrigerant to be lost, then go ahead and recover out that last little bit, but still keep just slightly above atmospheric pressure in the system. When you go ahead and open it, you wouldn't want it to suck air into the system so again never pull it down into a vacuum.

When you're about to do a repair like this, it's actually a good idea. Once you get down to that, you know just under one psi to go ahead and begin flowing nitrogen right at that stage, it's going to make your vacuums a lot easier and it's going to help prevent anything from getting into the system. If you want to go ahead at that point and pull your cores out, put your core remover tools on that's going to be a really good practice just to help prevent anything from getting in that system, especially if you're going to be cutting that system out or Maybe even unsweating certain parts of it, which sometimes that's just a practical practical thing to do. You want to have a little bit of nitrogen flowing at that point next step, you're going to remove the evaporator again you cut lines whenever possible.

I don't suggest unsweating, because refrigerant oil can catch fire and that can cause lots of heartache if there is an old line dryer in place, you're going to want to cut that out. One of the more controversial issues is: what happens if there is a factory line? Dryer inside the condensing unit best practices would say that in that case, you'd probably want to go ahead and just recover all the refrigerant cut that out and often even straight pipe it in that outside unit. In order to put the new liquid line dryer inside near the evaporator coil, which is the preferred place to put it but again follow your company and manufacturers guidelines on that, because that is a kind of a controversial thing. When you pull that old, evaporator coil out make sure that you are keeping anything from going into the lines and that's where flowing nitrogen can be helpful, you want to keep some tape or plugs to plug up the ends of those lines.

If you aren't in the process of flowing nitrogen at that time, just to prevent anything from getting into the ends of the copper, you do not want to leave copper open for any amount of time, especially nowadays with poe and pve oil. It can begin to become contaminated very quickly. I like to keep a little bit of blue masking tape and just kind of have that in my tool bag. So that way, i can just block it and again, masking tape is not going to keep everything out, but it will keep.

At least you know, particles out next you're going to put the new evaporator coil in including a new metering device and drain pan. I always suggest, when you're going to replace an evaporator coil just to go ahead and get a new valve if it doesn't come with one, it just makes good sense and handling an old valve and trying to reinstall it you're often going to break it, and so It's just makes good sense to go ahead and replace that if you can replace a new drain pan, that also makes a lot of sense. Some of the most common issues that we see is folks forgetting to get a new drain pan and valve and then, when they try to reinstall them those break. When you do reinstall, the evaporator coil make sure that it's level make sure that all of your proper retaining clips and all those things are put back into place and that everything is slid into place properly.

Then you want to go ahead and braise back in your evaporator coil with nitrogen flowing. Now again, you don't want to pressurize with nitrogen. You just want nitrogen to be flowing at 3 to 5 scfh. Make sure that you put a new liquid line dryer in and remove the old one? You can put it back in the same place as the old one or you can straight pipe the old one and put the new liquid line dryer inside because often they are outside and it is preferable to have them inside once you get everything all brazed in Properly again make sure you protect everything, you're, not burning paint you're, not burning valves, you're flowing nitrogen, that's very important.

The brazing process is really critical. On this i like to use wet rag. Even the product wet rag from refrigeration technologies to protect dryers. Then you need to do a pressure and bubble test on all of your joints.

Make sure that you're not dropping pressure watch that delta p, most of your modern probes or digital gauges, will allow you to monitor and make sure that that nitrogen pressure is not dropping. In addition to some soap bubbles, once you put the soap bubbles on, get it all cleaned up, so you don't have a mess on your hands. If you used any wet rag or whatever else, make sure to pull all of that off of your valves and get everything cleaned up and then pull your proper deep vacuum, you can use the one hose or the two hose method, but do it with your cores Out do it with large gauge hoses such as true blue and you're, going to find that it generally is going to come down pretty quick on an evaporator coil. Once that's all done, and it's held your vacuum with passing the decay test, then you're going to open your service valves, your both your suction and your liquid service valves, and then you are going to run the system generally speaking, you're going to run it in cooling At that point, i'm going to let it run for 15 to 20 minutes.

That's a good time to clean up. Do your paperwork also clean the drain? Obviously you just put a new drain pan in so that should be sound but clean. The drain line make sure that that's all nice and clear also when you do reattach your drain line to the evaporator coil. I forgot to mention that you want to use a good pipe dope, such as nylon white, to make sure that you get a good threaded seal into that drain pan once you let it run 15-20 minutes then go ahead and measure your suction pressure, otherwise known as Your suction saturation temperature, because it's really the temperature you're looking for your liquid pressure, which shows you your condensing temperature over ambient superheat, sub cooling delta, t and then to even be more thorough.

Do your delivered btus per hour, which is easy to do with measure quick and measure your static pressure? Because again, when you do a major repair like an evaporator coil, presumably you replace it because it was leaking. You have to assess the entire piece of equipment and one of the most overlooked. Things is airflow, make sure that the system airflow is proper at the very least, to make sure to do a solid visual inspection on everything else. Things like your blower wheel, as example.

If your blower wheel was also dirty during that time, i would suggest when the customer's spending all that money for a new evaporator coil, that you'd also remove and clean your blower wheel, like we've, talked about in previous episodes, your condenser coil, all those sort of maintenance Items make sure those are all done anytime. You do a major repair like an evaporator coil replacement or a compressor replacement. Once you do all these assessments of system operation just make sure that you button everything up and that you leave the system running and draining and fully communicate with the customer, and there you go. That's how you do a proper evaporator coil replacement, thanks for watching we'll catch you on the next video thanks for watching our video.

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