If you remove the vapor access port cap on a running air conditioning system, the low temperature brass on the inside of the port will condense water vapor from the air surrounding the port directly onto the port. This is because the air surrounding the port is often below the dew point. Don't remove the port cap until you are immediately ready to connect the gauge. Don't even connect the gauge unless you suspect a problem with the refrigerant charge level. We want to reduce

After servicing or adding refrigerant to an air conditioning system, add locking caps to the service ports if the system is in an accessible area. This reduces the chance of someone tampering with the refrigerant charge. The IMC code that requires this may or may not be adopted/enforced by your local municipality. However, it is a really good idea to do so to keep everyone safe and to keep the refrigerant charge intact. IMC Code 1101.10: " Refrigerant circuit access ports loc

There are a number of factors that lead to a residential NO A/C service call, so make sure to rule out the condensate line/switches! These switches may be wired to break either the R wire which is the 24V power to the thermostat or the Y wire heading to the outdoor unit contactor. To find such an issue, inspect the condensate area for any visual signs such as a secondary pan full of water! A simple issue like a clogged condensate trap or a clog at the condensate pump can lea

I just finished reading the book Unconformed, by Bryan Orr, from HVAC School. I invested about 5 hours spread over three days and let me...

(This image is courtesy of our friend JD Kelly @student_of_hvac ) In this refrigerant flow diagram, we see a simplistic piping arrangement for a heat pump running in cooling mode. When we take the complexity away, such as in this drawing, it allows a newer tech to easily follow the refrigerant path, especially as the refrigerant travels through the reversing valve and accumulator. Most of us don’t remember how overwhelming and complex things can seem when starting out in thi

(This image is courtesy of our friend JD Kelly @student_of_hvac ) This drawing shows how a low voltage wiring circuit can control a high voltage, high current load, such as a blower motor. Make sure to show this pic to your new apprentices! Remember that a thermostat acts as a simple switch. When manually turning on the fan, the thermostat connects the 24v R wire to G wire in the thermostat. The R wire is the 24 volt power wire which is typically red. The G wire is to control

Why do older coils seem to last a long time but ones that are only 10 or 15 years old leak? Energy transfer efficiency was not as much of a concern on older equipment and the tubing used in these older coils had a thicker outside wall dimension. On newer coils made over the last 20 years, the tubing in the coil is thinner, and in most cases, they have an increased surface area on the inside for quick heat transfer. The picture shows this increased surface area. The problem i

The answer is no because the refrigerant rejects heat in the condenser so the pressure and temperature of the refrigerant should lower. The refrigerant starts off in the condenser as a superheated vapor and after it rejects heat, it changes from a vapor state to saturated. After it rejects enough heat, the refrigerant changes to a subcooled liquid. In this picture, we see a saturated temperature of 105°F and a line temp of 93°F. 105 - 93 = 12°F of Subcooling It is possible f

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

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 -