Tag: leaks


Service valves are so basic and we see them with such regularity that we can miss them altogether.

Before I give the tips I want to address the tech who tells the customer it was “probably the service valve” or “the caps were loose” as a plausible reason for a leak without actually doing a proper diagnosis. Don’t make excuses, find the leak.

Now some tips.

#1 – Look before you connect

Look for oil around ports BEFORE you connect your gauges every time. If you have a leaking schrader and cap you want to know that before you connect your gauges and eliminate that leak. Keep in mind that a service cap is NEVER meant to be the seal from a leak, it does act as an insurance policy against a tiny leak in a schrader. If you find a leaking schrader, replace it.

#2 – Be Gentle With the Heat 

No matter the valve make sure you protect it from heat when brazing or soldering (Here’s looking at you Staybrite #8 techs).

The schraders should be out when brazing anyway, but the internals of the valve are also sensitive to heat. Ever see a valve leaking from the stem? Odds are it was overheated at some point.

When opening and closing the valve DON’T CRANK DOWN so hard. We all know you are strong, but when you crank it open and closed like that you can over-compress and damage the seals and mating surfaces. Snug is good, if you need to “put your back into it” it’s probably too much.

#3 – Check Your Seals

A 1/4″ service port is actually just a 1/4″ flare fitting. Technically they don’t NEED a seal if the cap is a flare cap (think Trane brass caps). The only trouble with the brass flare caps is they do need to be on pretty snug to seal.

Most manufacturers have gone to caps with a rubber O-ring seal inside, they seal better and they only need to be finger tight. Before installing these caps get in the habit of checking the seal EVERY TIME. Make sure it’s there and that it’s in flat.

I have seen many leaks caused by an O-ring that got put in cockeyed and depressed the schrader slightly when the cap was installed.

#4 – Try the New Fangled Technology

We used to always advise using a bit of refrigerant oil when making flares and even when reinstalling the top caps on service valves. The oil doesn’t really “seal” anything but it helps you get a snug fit without twisting or damaging anything (the technical term is “galling”).

Trouble is, we are going away from mineral oil and toward POE and POE fouls if it is exposed to the air (humidity) for too long. Granted, a drop of mineral oil on a flare isn’t going to hurt a POE system but IT’S THE PRINCIPLE DANGIT!

I have raged against the use of thread sealants like leak lock in refrigerant circuits for years. I’ve seen teflon tape and leak lock on flare fittings and Chatleff fittings… Teflon tape and leak lock do not belong on refrigerant circuit components folks. They aren’t designed for that purpose and if they get in the system they are gonna cause issues. In many gases gumming up the threads and mating surfaces with these products can inhibit a good seal by getting between the flare mating surfaces.

A product I like is called Nylog it’s a very thick but constantly viscous product (never gets hard) and it won’t hurt the system if a little gets inside because it’s made of refrigerant oil.

You can put a drop on the threads and mating surfaces of all your flares, chatleff connections (the valve connections with the teflon seals), top caps on your service valves, pipe threaded ports…. everywhere.. but just a drop

You can also use it on your hose connections to get a better seal when pulling a vacuum.

Just use a small amount otherwise dirt will stick all over everything.

#5 – Using the Right Wrench and Back it Up 

For those systems that still use flare hex caps its best to use a 9/16 box end wrench or flare wrench (shown above) and use a backing wrench when removing the cap. All it takes is ONE TIME of breaking it off to regret using a big ‘ol adjustable wrench.

— Bryan

 

Microchannel is a coil type used in many evaporator and condenser coils and can easily be identified by its flat tubes and fins between them that appear as waves between the tubes. The technology was developed for use in the automotive industry and is used for radiators and automotive A/C condenser coils.

These coils are made of all aluminum and are used because of their superior heat transfer due to increased surface contact between the refrigerant and the metal as well as the lighter weight and smaller refrigerant charge.

These coils have come under a lot of criticism by technicians due to an undisputed high failure/leak rate of the condenser coils in some systems. Some have felt these failures occur to inherent issues with the design while others have stated that the leaks were due to specific manufacturing issues on a few coils and that these issues are largely in the past. No matter how you feel it’s likely that microchannel coils are here to stay due to the increased heat transfer efficiency and decreased weight. Here are a few things you need to know when installing and servicing microchannel coils.

Don’t Pump it Down 

MicroChannel condensing units are not sent with the full system charge and must have the charge added to manufacturers specs even with a short (say 15′) line set with more charge carefully added for line length.

You cannot, and must not attempt to pump down a system with a microchannel condenser or you risk causing a catastrophic failure of the coil.

Instead, you must recover the charge when making a refrigerant circuit repair and then carefully weigh the proper charge in after the repair is made.

Use Proper Brazing / Evac / and Refrigerant Practices

It’s right in the name “micro” channel. The flat tubes have tiny refrigerant channels in them and they are susceptible to blockage by any solid contaminants in the system. Make sure to flow nitrogen while brazing, install a new liquid line drier after making a refrigerant circuit repair and pull a proper vacuum (as always). You also need to take extra care to keep shavings out of the system when cutting and reaming and keep tubing ends and hoses away from dirt and debris. For example, if you replace a compressor, anything allowed to get in your pipework will hit the condenser coil before it ever reaches the liquid filter/drier and has the opportunity to clog part of the microchannel coil.

Wash Carefully

Most manufacturers advise against using any cleaner on microchannel coils to avoid damage. Either use a garden hose, low pressure “fan” pattern pressure washer less than 100psi or a cleaner that is approved for use with microchannel and work carefully. The refrigerant channels go all the way to the edge of the coil and can be easily damaged if impacted.

The Charge is CRITICAL

When charging microchannel you will want to follow manufacturers specs and weigh the charge in whenever possible. If you see low suction doesn’t just start dumping in charge until you are certain it is a charge issue and not an airflow issue or a restriction. Subcooling on microchannel systems tends to be more erratic due to the lower volume of the condenser coil.

Install Thoughtfully

Many manufacturers will swear that microchannel is just as resilient as tube and fin coils, based on my personal experience I would suggest taking greater care to protect microchannel. It may make sense to keep microchannel away from areas of the lawn that will have equipment going near the unit and possibly shooting debris into the surface.

When a microchannel condenser leaks it is often fairly evident by the oil stain that appears on the surface. Because of the channels, these leaks can be quite small, so if you see the telltale oil spot it is best to investigate.

Repair

I confess I have never attempted a microchannel repair myself, but there are many who claim to do it regularly. Here is a video showing it being done.

So take extra care when installing and servicing microchannel systems when cleaning, charging and repairing.

— Bryan

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