There are many ways that technicians have tried to get around actually checking the charge of air conditioners and heat pumps with superheat and subcooling! I go into great detail explaining methods that you should use and methods that you should NOT use in the book “Refrigerant Charging and Service Procedures for Air Conditioning”. In this article I just want to highlight some of these shortcut methods to give you a taste of what junior techs are being told and may be choosi

On a mini-split ductless system, two copper tubes are needed to transport the refrigerant. These copper tubes are referred to as the line set and they connect the indoor head unit to the outdoor heat pump or condensing unit. Two flare connections are needed at the indoor head unit and two flare connections are needed at the outdoor mini-split unit. Things to consider: · A standard system has four flare connections while a multi-zone system has more flare connections for the a

A question that I get asked frequently is “Can I check the charge of a mini-split ductless unit with superheat and subcooling the same way I do on a conventional air conditioner or heat pump?". The answer is not exactly, but you can do some troubleshooting. A mini-split differs from a standard central air conditioning system in a variety of ways. Conventional split systems usually have a TXV (Thermostatic Expansion Valve) or a piston metering device, a single or two speed com

Do you have to do a triple evacuation if you can achieve a deep vacuum by only doing a single evacuation? Remember that the target vacuum...

Can you Measure Negative Superheat on an air conditioner when checking the charge? The Answer is NO! Time to check your gauges and temp sensors for accuracy! To briefly explain what is happening during the refrigeration cycle, the refrigerant exits the metering device and then enters the evaporator coil as a saturated refrigerant in roughly an 80% liquid and 20% flash gas mix. The refrigerant in the evaporator coil is lower in temp than the air crossing the evaporator coil. A

How do you tell if a TXV lost part of its bulb charge? If you are measuring a correct/high subcooling along with a high superheat and a low saturated temperature on the vapor line, there may be a liquid line restriction! Usually when a TXV bulb looses its bulb charge, it looses it slowly. One of the most obvious visual signs that a TXV has lost its bulb charge is if the top of the txv is very rusted. That would be the leak point of the refrigerant. If you are measuring a high

When checking the refrigerant charge of a running HVACR system, remember to attach your refrigerant hose to the vapor port right away. Don’t wait or outdoor humidity will condense in the port. Otherwise, attach the hoses while the system is off.

Make a Quick Free Refrigerant Leak Tester for the Schrader Valve (Valve Core) at the Access Port. Drill an 1/8” hole in the end of an extra port cap. Screw your testing cap to the port and add a drop of bubble leak detector to see if it blows a bubble. Remove the testing cap when done. This will avoid getting any bubble leak detector in your port or on the valve core. If there is a leak present, replace the valve core using a Valve Core Removal Tool. After leak checking, add

Most technicians in the HVAC field know the normal range of operation for the low-pressure side of an air conditioning system. This tends to be around 60 PSI to 85 PSI for R-22 and 105 PSI to 143 PSI for R-410A and is dependent upon operating conditions. On the high-pressure side of the system, there is a wide variation in pressure due to the wide outdoor temperature swing and due to the actual SEER (Seasonal Energy Efficiency Ratio) rating of the system being worked on. Beca

In this article, we will define both superheat and total superheat, calculate total superheat, explain how to use total superheat to check the refrigerant charge, and show where the measurement points are taken on an air conditioning system. Total Superheat Formula: Actual Vapor Line Temp – Sat Temp = Total Superheat So what does this mean and what is the difference between Superheat and Total Superheat? Simply put, superheat is the increase in temperature of the vapor ref

Use an additional valve core removal tool in your vacuum setup to valve off and protect the vacuum gauge sensor from oil contamination when refrigerant is added into the tubing. If the sensor gets oil on it, the sensor will not perform correctly and the sensor will need to be cleaned. Often this is accomplished with rubbing alcohol but always follow manufacturers' instructions for cleaning. CPS Vacuum Micron Gauge - http://amzn.to/2v1nM3O 1/4" Appion Valve Core Removal Tool -

In this article, we will define subcooling, calculate subcooling, explain how to use subcooling to check the refrigerant charge, and show where the measurement points are taken on an air conditioning system. Subcooling Formula: Saturated Temp – Actual Line Temp = Subcooling So what does this mean? Simply put, subcooling is the lowering in temperature of the liquid refrigerant in the condenser coil. On a split system air conditioner, the condenser coil is in the outdoor u

Regardless of the type of system or brand of thermostat, it is important to understand that there are many issues that can prevent a thermostat from operating properly. Some problems may seem like common sense while others tend to be a little more complicated. In this article, we will look at 10 thermostat or thermostat wiring problems that can prevent a heater or air conditioning system from working properly. Problem # 1: Thermostat Location The placement of a thermostat ca

Delta T is a term that gets thrown around in the HVAC field quite a bit, but what does it really mean, what is its purpose, and does it really matter? So, what is Delta T? For HVACR purposes Delta T can be referred to as the change in temperature that any medium (air, refrigerant or water etc.) experiences between two measurable points. It is important to note that for this measurement to be accurate it is critical for the medium to remain consistent and free of infiltrations

The filter drier, solenoid valve, and liquid line sight have unique responsibilities in an automatic pump down refrigeration system. To use each of these components to the fullest measure and for the greatest lifespan of the system, they must be placed in a specific order. These components are located after the receiver tank and before the TXV on the liquid line. The filter drier : This traps and stores any debris and water that may be inside the refrigerant circuit. Some fil

Short cycling means a gas furnace is running through its full sequence of operation for heat, it is providing heat in the building, and then it is shutting off before the thermostat is satisfied. The furnace then immediately turns back on to heat the building and turns off again. In order to troubleshoot a furnace you need to know the sequence of operation for heat. This requires that you know the type of furnace you are working on. In order to start the sequence of operatio

Pilot lights can be found on furnaces, water heaters, fireplaces, ranges, ovens and other appliances. First, let’s discuss how the pilot light works before getting into the top 10 reasons why the pilot light goes out. A pilot flame is lit with a manual push button spark ignitor or a handheld lighter while pushing down on the pilot plunger button found on the top of the gas valve. To light a gas pilot, the button on the combination gas valve must be pushed down which allows ga

Newer or faster methods do not always require expensive tools but do require a certain tool setup and step by step procedure. Some of the most labor intensive and time consuming procedures that we perform are checking the refrigerant charge, adding refrigerant, vacuuming a system, and recovering refrigerant. Not only can these procedures be done faster but we can perform them in such a way that will reduce frustration and lower the possibility of contamination in the system.

The triple evacuation is meant to be a means of dehydrating refrigerant tubing in a system that has high water content before refrigerant is introduced. This was and is still used on systems that have the potential for water to freeze while vacuuming. Does water inside the tubing freeze while vacuuming? Do you have to worry about this on most systems? That sounds like a whole other article for another week, but we will discuss some of the topic now! On air conditioning split

I have been asked, “Can we braze mini-split systems instead of flaring them?”. The answer, technically, is yes. The only question is in a warranty situation, will the manufacturer accept an indoor unit with the flares cut off? In most cases, they should accept them and the manufacturer reps that I have spoken with have said that it is not a problem. However, technicians should verify this themselves with the manufacturer of the particular equipment that they install. Of cours