How Moisture in the Refrigerant Lines Damages Compressors

How Moisture in the Refrigerant Lines Damages Compressors

Anytime technicians cut open the refrigerant lines to the air conditioning or heat pump system, we have to ensure the interior of those lines doesn’t get debris and other contaminants in them.  We can’t prevent air and moisture from getting in them, which is why we need to evacuate systems thoroughly.  If we don’t, a form of acid will develop inside the compressor and eat away at the protective lining that surrounds the copper stator windings.

Not only will the acid wear out the windings, but it can tear away the copper lining of the tubing itself.  That copper will land on the bearings or other components in the refrigeration circuit.  Other examples would be the TXV or other metering devices.  Once this starts, friction starts building up, causing the compressor to work harder to do the same work.  Over time, the friction builds up so much the compressor seizes or burns out. 


Moisture and POE Oil


R-410A systems use Polyol ester oil (POE Oil) which is a hygroscopic oil. POE oil retains water in the air a lot more than the mineral oil (R22) systems.  That’s why we have to evacuate the system of as much moisture as possible.  Technically, we’re not supposed to leave the lines open for more than 15 minutes.  That’s hard to do when replacing a major component like a compressor or evaporator coil.  If exposed long enough, it’s best to replace the compressor oil to the levels printed on the data label on the side of the compressor.   This is because no matter how long we have the unit on a vacuum, that moisture will never be removed from the compressor oil.


When a system is flat on charge, meaning there is no refrigerant left in the system because it all leaked out,   it can be assumed that air is now in the system.  There’s no vacuum left in the lines, so the leak needs to be repaired and then evacuated to 500 microns or less again to get it back to normal.  Does this mean if the system is flat, the lines have been open longer than 15 minutes?  I would assume so.  Should we change the oil in the compressor?  I guess so.  Do any techs do it?  Probably not.



Filter driers catch remaining moisture


Because it’s so hard to get all the moisture in the lines evacuated, we always install a filter drier.  A good filter drier has desiccants inside it that will absorb residual moisture in the lines as it flows through the system.  Even then, only so much moisture can be absorbed by a filter drier.  A clogged filter drier will start restricting the normal refrigerant flow and even cause flash gas causing abnormal operation.  You can tell if a filter drier is clogged by measuring the temperature of the liquid line before and after the filter drier.  If the difference is 3 degrees or more, changed the filter with a new and properly sized one.


It’s so important for technicians to ensure there is no moisture from the atmosphere left in the lines when we turn the system on.  There are tools, components, and procedures to help with this. If we don’t do it right, we are only doing a disservice to the customer because the electrical and mechanical parts of the AC system will eat away from acid that forms inside of it.  


Professional, knowledgeable service is essential when it comes to the air conditioner.  Don’t just call anyone out to service your system.  Call Fox Family or even book online  at the top of the page.

That’s it for this week.  Check us out on the next blog!

How I Troubleshoot a PSC Condenser Fan Motor on an Air Conditioner

Troubleshooting a Condenser Fan Motor

Condenser fan motors come in a couple of forms.  PSC style and ECM style.  PSC motors are easily identified by the run capacitor that comes inside the service panel with them.  ECM motors are electronically commutated motors run on their own power.  Today we’re talking about the PSC condenser fan motor which you’ll find on a lot of the basic 10 to 14 SEER single-stage systems out there. 

There are only a few things that can go wrong with your typical PSC motor.  Voltage from the panel isn’t sufficient, the contactor is bad, the capacitor is bad, or damaged parts inside the condenser fan motor.

Why Is The AC Making A High Pitched Noise?

I’ve gotten this call before.  The customer says the outdoor unit is making a very pitched noise.  Louder than they’ve ever heard!  When you get to the house and turn on the AC, you walk up on the outdoor AC unit and find that the compressor is pumping the refrigerant, but the fan on top is not spinning.

What’s happening here is the condenser fan blade isn’t spinning which normally removes the heat from the outdoor unit.  If it doesn’t, the compressor will overheat and shut down, but not before putting up a screaming hissy-fit.  After that, the internal overload switch on the compressor opens.  It takes about 45 minutes or so to cool back down, and then retry running again.  Heats up, shuts down, cools off, restarts, and over and over.

In this case, you likely have good voltage to the system but just to be sure make sure you have about 240 volts to the load side of the contactor while it’s running.  This lets you know the line voltage is good and the contactor is good in one quick test with your multimeter.

You only have so much time to do this before the compressor shuts down, but next, I usually take a stick or something and try spinning the fan blade with it.  If the fan starts spinning after giving it a little nudge, I’d check the capacitor next.  That capacitor is what helps it start and run efficiently.

If the capacitor checks out good, then you know you have proper voltage getting to the motor, so the condenser fan motor is bad.

If the fan blade doesn’t keep spinning after you nudge it, the capacitor could be good, but still, check it.  If it’s good, the condenser fan motor is bad.

Checking The Condenser Fan

I’ve seen this happen when a big windstorm hit an area recently and knocked some branches down into the top of the AC.  The shroud on top usually does a great job of protecting the fan blade, but in this instance, a stick wedged itself in there and caused the motor to burn out.

Another reason this can happen, especially on universal replacements is the inside of the motor got wet.  These motors come with rubber plugs sometimes.  These plugs have to be placed on the top side of a downward mounted fan, and in the bottom of an upward facing motor.  The ports on the opposite sides should remain open, so that any moisture that does get into it, can drain out.  Happens all the time!

I would say check the fan motor for a short to ground, but the main breaker or service disconnect fuses would have usually tripped by now.  So let’s check the motor windings first to see if we have an open or damaged winding.

Take the wires off the contactor and the capacitor that leads to the fan motor.  Refer to your wiring diagram that comes with the AC and check your ohms (resistance) between Common (Purple or C on the capacitor) and Start (Usually Brown but was attached to Fan on the capacitor.)  You should read a fairly low amount of resistance here.  If you read OL on your meter, then you have an open Start winding

Common and Run (Black, or the only wire that’s coming from the contactor to the fan motor.)  You’ll likely measure a lower amount of resistance here.  If it’s OL, then you have an open Run winding.

If you have an OL on both of the motor’s windings, the motor’s internal overload switch could be open.  If you allow time for it to cool down, and it still wont run, replace the condenser fan motor.

Just in case you do have good windings, let’s double check to make sure the motor isn’t shorted to ground.  You can check with your ohm meter, but I usually just use the continuity setting on my meter.  Check between the frame of the motor and each winding.  Common, Start, and Run.  Make sure you’re not using a painted surface for the frame.  You want to use a metallic base for this test.

Condenser motor

If you have continuity between any of these and the frame of the motor, replace the condenser fan motor.

Well, I hope this helps you troubleshoot your next condenser fan motor.  This is one of the easier components to check.

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Why Is my Air Conditioner So Loud?

Making Sense of the Noises Made by Your Air Conditioner

If you’re reading this post, it’s probably because your AC is making some crazy noises lately that you’re not used to.  Or you just moved into a house and the AC has never been used until now, and of course now it’s making strange noises.

Of course, it is a machine, and machines make noise.  But why is this thing getting noisier and noisier every summer?  Today I want to share some things I’ve seen out in the field working on other people’s AC systems that might help you isolate where the noise is coming from and some possible reasons why your AC is so loud.


Your air conditioner is very likely on the side of your house.  For some people it’s on the roof.  And for obvious reasons, a roof mounted AC will definitely make some low consistent vibration because its mounted to the roof joists, which are connected to the wall studs, and the rest of the house.  So, for those of you with rooftop air conditioners or complete package units that are so common here in California, that is something you may be stuck with as long as it’s up there.

Also, as I’m sure you already know, these are machines and machines make noise.  Typically, the older they get, the louder they get.  Understanding that, let’s dive into some real issues you might be experiencing on systems that aren’t 20 years or older.

Breaking It Down

I want to break this into two parts:  Things you can fix yourself, and things you might want to have a real HVAC technician look at.  Notice I said real technician, and not a person dressed like a technician who is just there to sell you a new system.  These deceiving salesmen and saleswomen are only in it for the money and have no interest in saving your system.

Remember, if the parts are available, and yours very likely are, or can at least be retrofitted with correctly matched universal parts, it can be repaired.  You’re in charge.  Like I always say, your system is designed to last about 20 years before you start to consider getting a newer system.  But, it’s really about where YOU want to put YOUR money and not about the technician’s ideas.

Here are some loud noises you’ll probably need a professional to address:

A Loud Compressor

An AC that sits on the side of your house only has a few parts in it that will make some crazy noises.  Inside the shell of that outdoor unit is a compressor, a fan motor, and an on/off switch called a contactor.

The biggest part, the compressor, pumps the refrigerant through your system much like your heart does the blood in your body.  This pumping requires two spiral plates to rotate in an elliptical motion.  Sometimes those plates (more commonly called scrolls) can chip or come out of alignment creating the loudest, most awful noise you’ve ever heard, especially if it happens at night when you’re sleeping.  It’s a grinding noise or loud clacking noise that cannot be missed.

We can’t just take off the cover and look inside to fix it  It’s a hermetically sealed part that can’t be opened by anyone.  If this noise can’t be fixed from outside the compressor, you will likely agree with your technician when you’re told it needs to be replaced.

An Unforgettable Noise

I personally remember a house in Coloma, CA that was doing this.  The loud noise never stopped for the customer as they ran their AC.  It wasn’t even cooling the house!  It was just running and running and running.  As we approached the unit, on the complete other side of the house, it got louder and louder.  After some testing, I noticed the compressor wasn’t pumping like it should, yet it was still making this loud noise.  This was THE loudest air conditioner I have ever heard.  It was a 10-year-old Bryant AC, so we changed that compressor out, and the system ran fine from there on out.

I’ve also come upon an AC where the compressor — one just like we were talking about — wasn’t out of alignment or broken, but had an internal part called a bypass stuck open.  This created a loud squealing or screaming noise indicative of high pressures and high heat inside that compressor.  Before replacing this part though, a technician should determine if the refrigerant pressures within the system are adequate, as well as some other tests.  Whatever the solution, be aware of some noises that this compressor makes.

Noise from the Fan Motor

Another time we might have to replace the part making the noise is on the condenser fan motor.  That’s the fan blade you’ve probably seen that spins on the top of your AC when its running.  I’ve come out on a house before where the motor that spins the fan blade is making a high-pitched whistling noise.  As I looked around the AC, my ears and eyes finally isolated the noise coming from this motor.

Every AC fan motor has ball-bearings that help the motor shaft spin.  But these bearings are sealed and can’t be accessed to lubricate them, which would likely solve the problem.  So, in this case, the motor must be replaced if you want the loud noise to cease.  Finding the right motor can be tricky, so it’s probably best to let a qualified technician do it.  Just putting a motor with the wrong speed setting will cause cooling issues you won’t be happy with.

A Buzzing  Contactor

Your AC has an on/off switch called a contactor.  The thermostat inside your home tells it when to switch on and off by sending a low voltage signal.  To plates come together at that very moment to allow the high voltage though to the parts we were just talking about before:  The compressor and the fan motor.  As the years go by, pitting caused by the high voltage arcs happening between those two plates as they come together can get to a point where the two plates won’t come together all the way creating a loud buzzing noise.  Not as loud as that compressor I was telling you about earlier, but loud enough to get your attention.  Getting into the electrical panel of an air conditioner can be intimidating and the potential for an electrical shock.  Again, making a mistake here can lead to more expensive problems.

What You Can Do

Let’s review some loud noises you can likely isolate and fix yourself.  If you don’t feel comfortable doing it, just call Fox Family Heating Air and Solar and our techs will be happy to fix this stuff for you.

Make it Level

If your system starts making loud noises, a good first step is to make sure the unit is level.  If the AC isn’t flat, oil inside the compressor might not be lubricating the way it should be.  Just be careful not to bend the copper lines coming from the wall to the AC.  This may strangle the refrigerant and cause more expensive problems.

Check for Debris

Next, sometimes sticks and leaves can block the fan blade on top of the AC from spinning, which causes some strange noises with the AC.  Go outside and remove any sticks or toys that are preventing the fan blade from spinning.  The damage may already be done to it, but you can at least try.

Tighten a Rattling Fan Shroud

Also, the fan blade is protected by a round metal shroud that is there to allow warm air to flow out of it, but also protect people from getting their fingers inside of the AC.  Sometimes this shroud starts rattling as the screws that hold it down start vibrating loose, possibly creating a larger hole than the screws were initially sized for.  As the AC runs, the rattling can be annoying.  This tends to happen on older systems.

The solution is to install slightly wider screws that will hold the shroud down securely.  This would fill the hole better and crate less noise.  Another trick we like to do is get these little rubber isolation pads and use them as shims to help dampen the vibration between the shroud and the frame of the AC.  This can really help in reducing the vibration or rattling noise on your aging system.

How to Prevent These Problems

Preventive maintenance is key.  If Fox Family can get out to your system twice a year and do the necessary checks and clean your system, we know we can make your system last longer.  A clean system is a healthy system.  But if you don’t want to hire us to do these checks for you, no problem.  Here are some things you can do on your own to help your system out.

About Filters

Changing your filters as needed.  I always say if your filter isn’t perfectly clean, it’s time to change it out.  The filters we buy at my house come with a cardboard trim around it with some white mesh or fiberglass as the filter media.  At about $7 a 3-pack, they’re the cheapest filter sold at the store.  If that filter isn’t perfectly white, then I change it out.  I’m not tied to it because I didn’t buy an expensive filter.

Some people buy these $20-dollar filters.  Its almost like they want to hang on to these filters as long as they can, even though they are brown or gray in color now.  Eww!  That’s the air we are breathing!  That’s the air the children in the house are breathing.  This dirty, dead skin, pollen laden filter is now a contaminated breathing mask essentially for your AC.  If that dirty filter were up against your mouth as you breathed in, you would definitely change it.  So that’s what I compare it to.  You get the picture.  And I’m sorry for getting too graphic there.

Another reason to change that filter is because super dirty filters can suffocate the compressor.  This can cause burnouts, clogged evaporator coils, and other cooling problems.  If the air filter is too dirty, the evaporator coil can even form into a block of ice.  This causes serious cooling issues, including loud screaming compressors that can’t circulate refrigerant anymore.

Keep It Clean

Periodically washing the AC outside unit every now and then is a good idea.  It doesn’t take much energy to do, and it doesn’t cause  any soapy solutions to do this either.  Another cause for loud squeaking noises is a clogged coil.  But if the coil on the outside AC gets clogged like a dirty air filter does, high pressures can occur in the refrigerant system, creating noise.

Please don’t use a pressure washer.  You’ll destroy the parts of the system that are crucial for air flow and heat transfer.  But you do want to use just enough pressure from the hose to start knocking off loose dirt and small debris down to the ground.   Also try to  focus on not bending any of the fins that surround the AC.  Called the condenser coils, if you flatten them, you can create some crazy noises with your AC.


I hope this has helped you understand where some of those strange, loud noises coming from your outdoor air conditioner.  If you have any questions or doubts that you can isolate the noise, let us know at Fox Family Heating, Air and Solar.  We’d love to help keep your system running for a long time!

Thanks so much for stopping by and we’ll see you on the next blog post!

Why Your Air Conditioner Isn’t Blowing Cold Air

Air Conditioner Not Blowing Cold Air

Why Isn’t My Air Conditioner Blowing Cold Air?

The air conditioning system in your Sacramento home may not blow cool air as strongly as you expect due to several reasons. Here are some common culprits to investigate or ask your HVAC  professional to address.

Blower Malfunctions

The blower of the air conditioning system is responsible for forcing air to flow throughout the ductwork in your home. Any defect in the blower will result in a weakened flow of air to the different sections of your home. The blower may have been clogged by dirt to the extent that the blades cannot move freely. A thorough cleaning can fix this problem and get the blower working again.

However, you may need to have the blower motor replaced in case the motor has aged and can no longer work. This replacement project should be done by a Sacramento HVAC repair technician since the process is too complicated for a layperson to perform.

Ductwork Problems

Do you have flex ducts in your HVAC system? Such ducts can easily become crimped and stop the flow of air to a section of your home. The airflow can also be weak if a duct becomes disconnected and starts discharging air into the attic instead of into the room supplied by that affected duct.

Dirt can also accumulate and constrict the ducts through which air flows to the different living spaces in your home. The best way to fix this problem once and for all is by asking an HVAC professional in Sacramento to check the entire system of ducts in order to clean and restore those that are disconnected or crimped.

A Frozen Evaporator Coil

The air conditioning system supplies cool air by passing the warm air from your home over the evaporator coil in the outdoor unit of that AC. Anything which affects this cooling process can cause a weak airflow. For example, a refrigerant leak can cause ice to form on the evaporator coil. Consequently, it will be harder for air to flow over that evaporator coil. You will then notice that the flow of air from the vents is weak.

Similarly, dirt can also accumulate on the evaporator coil and restrict the flow of air over that coil. This problem will keep worsening until the evaporator coil fails completely due to the accumulation of heat around it. Start by turning the AC unit off in order to allow the ice on the evaporator coil to melt. Next, use a soft-bristled brush to clean off any dirt which may be on the evaporator coil. Turn the unit back on and observe whether the airflow improves. Call a Sacramento HVAC technician for help in case the problem persists.

Air Filter Problems

Another possible reason the AC isn’t blowing cold air is because of a clogged air filter.  This can also create an opportunity for the flow of air to become slow. This is because the accumulated debris prevents air from flowing through the filter media as easily as was the case when the filter was still new. Cleaning out or replacing such a dirty filter can cause the AC to blow harder.

The problem could also be due to the use of an incorrect filter for the AC in your home. Air filters have a rating for the amount of air that they can let through every hour. Installing a filter that isn’t rated for your HVAC system can slow down the flow of air around the home.

Make sure that you bought the correct type of filter for your AC by checking the user manual that came with the air conditioning unit in your home. Replace that filter with an appropriate one so that the airflow challenge is fixed.


As you can see, some of the reasons for the AC not blowing cold air can be fixed by a homeowner while others require expert help. You should, therefore, ask a Sacramento HVAC repair technician to inspect and fix the system in case your DIY efforts haven’t yielded any positive outcome.

If you have questions or concerns about the performance of your air conditioner, give Fox Family Heating and Air a call. We deliver honest and efficient service each and every time!

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