Head pressure hvac

R410a min. head pressure. before i ask let me say i am certified in R410a and i work with it almost everyday so please keep that in mind. i was always taught that if it was below 65 oat you have to keep a min. head pressure. what is a min head pressure for 410a? Reply. 02-15-2009, 05:31 PM #2.

Head pressure hvac. Jan 27, 2024 · Head pressure in HVAC refers to the pressure exerted by the refrigerant within the condenser unit. It is a critical factor in the functionality and efficiency of an HVAC system. Understanding head pressure is essential for maintaining a well-functioning HVAC unit.

Helps prevent evaporator freeze-ups, liquid-slugged compressors, low pressure cutouts and overshoots seen with on/off & pressure switch controls. Mode of Operation ICM Head Pressure Controls operate as temperature-sensitive motor fan speed controls. Head pressure is regulated during low ambient conditions by varying the amount of airflow through

The main reasons your compressor will have simultaneously low head pressure and high suction pressure is due to: Bad or leaky compressor valves. Worn compressor piston rings. Leaky oil separator return line. Your compressor valves may become inefficient due to poor sealing from dirt and debris deposits.In order to correct this R-22 was phased out across the world. Here in America our phase out began in 2010 and the refrigerant will be completely phased out in 2020. Taking R-22’s place is the HFC refrigerant blend known as R-410A, our Puron. As I write this article, in 2019, there are still thousands of R-22 machines out there, but they … Troubleshooting Refrigerant Charge to Determine a Bad TXV. If your suction pressure is staying the same while adding refrigerant, and your head pressure is shooting up while the suction pressure is staying the same, your TXV valve is probably bad. If you do your homework and suspect that the TXV bulb lost charge, it’s probably a better idea ... Restriction in the Refrigerant Flow. Another cause of low suction pressure high head pressure can be a restriction in the refrigerant flow. This can be caused by a blockage in the refrigerant lines or a problem with the compressor, and can lead to low suction pressure and high head pressure. 3. Faulty Compressor.How to diagnose high head pressures at the air conditioning or heat pump compressor: What are the causes of high head pressure at an air conditioner or heat pump compressor motor? This article lists twelve causes of high head pressure and explains their causes, effects, and diagnosis.

Figure 1. Low ambient control. January 6, 2014. When refrigeration systems are exposed to low ambient conditions, the condensing pressure (head pressure) will fall. If the head pressure gets too low, the metering device will not have enough pressure drop across it to operate properly.May 4, 2022 ... It's all about the right control of your condensing pressure. Check out the mechanical KVR–NRD combination shown here; then head over ...Mar 22, 2024 ... High head pressure #hvac #hvactechnician #hvactech #hvaclife.If you’re looking to start a career in the HVAC industry, or if you’re already in the field and want to expand your knowledge, finding a free HVAC training online course can be an ...Dec 5, 2020 ... HPCV/ head pressure control valve / head ... D2D NY Real World HVAC Simplified. 16.2K ... HVACR Service Call: Water Source Refrigerator With High ...The need for head pressure control. June 1, 2000. There are various methods of head pressure control, some of which contractors may not be aware of. They can have a dramatic effect on the performance of refrigeration systems and components. Refrigeration systems are designed around certain criteria:Jul 9, 2019 · On 2019-01-24 by Rkg1963 - Nordyne heat pump head pressure shuts the system down at 600 in heat mode. Have a 3 ton Nordyne Residential HeatPump Condenser that the head pressure run up around 600 before it shuts down . Only in Heat mode. Pressures look great in Cool mode. Any ideas as to why this is? On 2017-11-01 by David The Cost of High Head Pressure. January 5, 2001. Table 1. Based on recopricating compressor operating at 30 psig suction, °0 superheat, °10 subcooling, 92% motor efficiency, year-round operation. Figure 1. The effect of rising head pressure.

Aug 17, 2023 ... Head pressure control for low ambient conditions... The ICM Controls 325A uses a thermistor to monitor pipe temp and control condenser fan ...Bryan with HVAC School goes over AC pressures, subcooling, and superheat in his troubleshooting mindset presentation from the BTrained HVAC training event in Birmingham, AL. Bryan also talks a bit about his educational photo-sharing app, MechPic. The suction pressure and suction saturation give us an idea of the refrigerant’s boiling temperature.In air conditioning applications, compression ratios of 2.3:1 to 3.5:1 are common, with ratios below 3:1 and above 2:1 as the standard for modern high-efficiency air conditioning equipment. In a 404a medium-temp refrigeration (cooler) application, 3.0:1 – 5.5:1 is a common ratio range.Low suction pressure and high head pressure is a condition where there is a decreased refrigerant pressure in the AC system and at the same time a high output pressure in a compressor. This condition is mainly caused by a defective or malfunctioning TXV valve. An expansion valve is a device that regulates the flow of the liquid refrigerant …Jan 16, 2024 · What Is Head Pressure In HVAC? Head pressure is the pressure that is created by the gas compressor within the air conditioning unit. This is something that is typically measured when there is believed to be a refrigerant issue. Head pressure that is within a reasonable range is no cause for concern. High head pressure creates problems for the ...

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Dec 20, 2023 · What exactly is head pressure in an HVAC system? Head pressure, also known as high-side pressure, is the force that the compressor in your HVAC system uses to push refrigerant through the cooling cycle. It’s crucial for efficient operation. Jun 11, 2021 · Head pressure is also sometimes referred to as discharge pressure or high side pressure. The output side of the compressor in an HVAC unit generates this pressure, and it can be affected by many variables. For instance, the condenser fan’s size and speed can play into the head pressure, as can the condenser coil’s overall condition and how ... Welcome to HVAC-Talk.com, a non-DIY site and the ultimate Source for HVAC Information & Knowledge Sharing for the industry professional! ... If it weren't for the high head pressure and the high SH and SC I'd leave it alone. THX Jim Reply . 06-07-2021, 04:45 PM #2. pecmsg. View Profile View Forum Posts View Forum Threads …Refrigeration Rack System consists of multiple compressors piped together connected to multiple refrigerated cases. It allows the use of multiple compressors and condenser fans for cooling more efficiently, conveniently and compactly as compared to traditional individual refrigeration systems. Multiple compressor attached allow variable …What Is Head Pressure In HVAC? Head pressure is the pressure that is created by the gas compressor within the air conditioning unit. This is something that is typically measured when there is believed to be a refrigerant issue. Head pressure that is within a reasonable range is no cause for concern. High head pressure creates …Jul 5, 2019 ... ... pressure range of what a R410A air conditioner pressures should be. Note that in order to handle or work with refrigerant you need to be ...

HPCV/ head pressure control valve / head master, help the air conditioning unit maintain normal operating pressures during colder outdoor temperatures below ...Suction Pressure: 65 PSIG (roughly 10 degrees) Discharge Pressure: 205 PSIG (roughly 72 degrees) Suction temp: 61 F Discharge temp: 64 Superheat: 51 F Subcool: 8 F Trane R410A system has a design subcool of 10 +/- 3 degrees so my subcooling is within the threshold.Feb 6, 2013 · If you are wanting to maintain 180 psig. head pressure the controls would be set as follows: Cut-in Cut-out. Fans 1-2 180 psig. 160 psig. Fans 2-4 200 psig 190 psig. As you can see, this causes fluctuation of the head pressure and can result in expansion valve hunting and poor superheat control. I was working on a water source heat pump Trane serial number# W04C11546 MN# GEVB02411J0110TL. The unit is an upflow with the compressor compartment being on the bottom and the fan and coil on top. The problem is that the unit will run for about one minute in cooling mode then goes off on high head (400 psi r-22). Unit runs fine in heat.P215PR. P215PR direct-mount single phase condenser fan speed controllers are pressure-actuated to vary the speed of single-phase motors. Speed variation of the fan on an air-cooled condenser controls the refrigeration system’s head pressure, for optimum performance year-round. These controllers can be used with non-corrosive refrigerants. Pressure vs. Head (6) can be transformed to: Δ h = (p 2 - p 1) / γ (7) Δ h express head - the height difference of a column of fluid of specific weight - γ - required to give a pressure difference Δp = p 2 - p 1. Example - Pressure vs. Head. A pressure difference of 5 psi (lb f /in 2) is equivalent to head in water Features. The HP2C2 provides the following: Can be operated stand-alone or up to two modules can be daisy-chained together and connected to a VCM-X Modular E-BUS, VCM-X WSHP E-BUS, or SA E-BUS Controller. Monitors up to four individual head pressure transducers. Provides control of condenser output signals based on the highest reading …A feeling of dizziness and pressure in the head may result from a migraine headache, allergies, sinusitis, ear infection, or high blood pressure. However, it may have a different underlying cause ...A thermostatic expansion valve (TXV) (see Figure 1) is a refrigeration and air conditioning throttling device that controls the amount of refrigerant liquid injected into a system’s evaporator—based on the …These questions and answers about causes of and cures for high head pressure in an air conditioner or heat pump compressor motor were posted originally at REFRIGERANT HIGH HEAD PRESSURE DIAGNOSIS - be sure to review the high A/C or heat pump compressor head pressure causes there.

Typical Low Side Pressure Range for R410A in the field: 115-120 psi. Typical High Side Pressure Range for R410A in the field: 410-420 psi. By 2025, high Global Warming Potential (GWP) refrigerants with a GWP of over 750, will be banned together with the systems using that gas. R410A has a GWP > 2,000.

145 °F. 571.7 psig. 150 °F. 607.6 psig. 155 °F. 645.2 psig. You can see that this R410A pressure chart includes high and low side pressures at temperatures ranging from -60 °F to 155 °F. Higher temperature equates to higher pressure. Here are 4 examples of how you can use this chart:A compressor may have a discharge pressure of 290.6 PSIG and a suction pressure of 62.3 PSIG. We’d find our compression ratio using the following steps: 1. Add atmospheric pressure to both gauge pressure values to get the absolute pressures. 290.6 PSIG + 14.7 PSI = 305.3 PSIA. 62.3 PSIG + 14.7 PSI = 77 PSIA. 2.Head pressure in an HVAC system is the force that refrigerant exerts within the compressor. It’s a key player in moving refrigerant through the system, including head pressure controls. Think of it as pushing a fluid through a pipe at home; more pressure control means faster movement. This pressure needs to be just right.HVAC Static Pressure - Main Duct Must Reduce in Size. HVAC static pressure is maintained in your home by making the main supply duct get smaller the farther away it is from the furnace. Tim Carter. HVAC static pressure needs to be maintained equally in all ducts for you to be comfortable in your home.The pressure created on the output side of a gas compressor in a refrigeration or air conditioning system is known as discharge pressure. It is also known as high side pressure or head pressure. A refrigerant restriction indicates an extraordinarily high discharge pressure combined with an external suction pressure.Here are some of the symptoms of this system: • Higher than normal discharge temperatures; • Low condensing (head) pressures and temperatures; • Normal to high condenser subcooling; • Normal to high superheats; • High evaporator (suction) pressures; and. • Low amp draw. Higher than normal discharge temperatures:A …The need for head pressure control. June 1, 2000. There are various methods of head pressure control, some of which contractors may not be aware of. They can have a dramatic effect on the performance of refrigeration systems and components. Refrigeration systems are designed around certain criteria:Pressure to Head Unit Converter Pressure vs. head units - like lb/in 2, atm, inches mercury, bars, Pa and more. Pumps - Head vs. Pressure Converting head (ft or m) to pressure (psi or bar, kg/cm2) and vice versa. Static Pressure vs. Head Static pressure vs. pressure head in fluids. Water Pressure vs. Head Pressure in pounds per square inch (psi ...1. Since the pressure differential across the thermostatic expansion valve port affects the rate of refrigerant flow, low head pressure generally causes insufficient refrig-erant to be fed to the evaporator. 2. Any system using hot gas for defrost or compressor capacity control must have a normal head pressure to operate properly.2 stage Carrier 48TJE12-High Head Pressure. Hi! Working on a Carrier roof top 48TJE12 2 stage... Everything turns on for a call for cooling. The head pressures goes to 400 and the internal pressure valve on both compressors kicks in. The suction is at 85 and drops a little.

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condenser head pressure what should it be ??The most common causes of pressure in the head and face include allergies, ear infections, the common cold, muscle tension, sinusitis, stress and tension headaches. Increased intra...R410a min. head pressure. before i ask let me say i am certified in R410a and i work with it almost everyday so please keep that in mind. i was always taught that if it was below 65 oat you have to keep a min. head pressure. what is a min head pressure for 410a? Reply. 02-15-2009, 05:31 PM #2.Mar 25, 2024 · Head pressure is normally the pressure that a compressor makes in air conditioning, refrigeration, and heating systems. Head pressure in a normal range is not an issue, but a high head pressure is always an issue for your system. The compressor in an HVAC system has a very crucial role. It circulates the refrigerants throughout the system such ... An indoor txv not bypassing in heat mode will cause a high head pressure condition. It becomes a discharge gas restriction. This makes sense. OP should check TXV and make sure it is correct for a heat pump. Needs to have the reversing check valve or a bypass circuit with a seperate check valve.Head pressure is the force that refrigerant exerts in the condenser section of your HVAC unit, affecting the cooling performance and efficiency. Learn how outdoor temperature, dirty coils, overcharged refrigerant and other factors influence head pressure and how to maintain optimal levels.In order to correct this R-22 was phased out across the world. Here in America our phase out began in 2010 and the refrigerant will be completely phased out in 2020. Taking R-22’s place is the HFC refrigerant blend known as R-410A, our Puron. As I write this article, in 2019, there are still thousands of R-22 machines out there, but they …May 19, 2022 ... ... Head Pressure Troubleshoot on call(Bad motor and subcooler). 15K views · 1 year ago ...more. Gendron HVAC-R.Jul 5, 2019 ... ... pressure range of what a R410A air conditioner pressures should be. Note that in order to handle or work with refrigerant you need to be ... Various experts and professionals claim that head pressure for a 410A system should be 400 to 418 PSIG on the high side while 120 to 130 PSI on the lower side. Anything more than this range is considered high head pressure. This value may vary a little bit depending on the weather and other external conditions. 1. Since the pressure differential across the thermostatic expansion valve port affects the rate of refrigerant flow, low head pressure generally causes insufficient refrig-erant to be fed to the evaporator. 2. Any system using hot gas for defrost or compressor capacity control must have a normal head pressure to operate properly.Jan 6, 2014 · To replace a defective low-ambient control valve with a pressurized dome charge, follow the steps below: 1. Recover the refrigeration system’s refrigerant; 2. Cut the process tube on the valve’s charged dome to remove the pressure charge (wear safety glasses); 3. With a torch, heat the valve until the solder melts; 4. ….

Temp (°F) Pressure Temp (°C) Temp (°F) Pressure Temp (°C) Temp (°F) Temp (°C) Pressure Temp (°F) Pressure Temp (°C)Step 4: Measure the Static Pressure at the Return Grille. After measuring the static pressure at the supply grille, it’s important to measure the static pressure at the return grille. This step helps you assess the resistance to airflow in the return ductwork, including the air filters. Here’s how to do it:If you’re considering a career in the heating, ventilation, and air conditioning (HVAC) industry, one important credential you should consider is the Environmental Protection Agenc...On 2019-01-24 by Rkg1963 - Nordyne heat pump head pressure shuts the system down at 600 in heat mode. Have a 3 ton Nordyne Residential HeatPump Condenser that the head pressure run up around 600 before it shuts down . Only in Heat mode. Pressures look great in Cool mode. Any ideas as to why this is? On 2017-11-01 by DavidWhat are A/C system design conditions while running? 95°F outside, 75°F inside, humidity 50%. T or F - The inside relative humidity adds a significant load to the evaporator coil and must be considered part of the load. True. If the outside temperature increases, what happens to the head pressure and system capacity? Head pressure is essential to the proper operation of your HVAC system because it helps maintain the refrigerant in a liquid state. If the head pressure is too low, it can indicate problems like insufficient airflow or refrigerant charge, which can lead to poor cooling efficiency. Conversely, if the head pressure is too high, it can mean issues ... Contents [ hide] 0.1 Basics of Head Pressure. 0.2 Causes of Changes in Head Pressure. 0.3 Significance of Monitoring Head Pressure. 0.4 Symptoms of Abnormal Head Pressure. 0.5 Impact of High Head Pressure. 0.6 Impact of Low Head Pressure. 0.7 Solutions to Regulate Head Pressure. 0.8 The Role of Thermostatic Expansion Valves (TEVs)Lennox Learning Solutions teaches you what causes high head pressure on a heat pump in the heating mode.There is several factors that can cause hight pressur...Jan 16, 2011 · Head-Pressure Control Valves Operation. The ORI head pressure-control valve is an inlet pressure regulating valve. It responds to changes in condensing pressure only. The valve designation stands for opens on rise of inlet pressure. As shown in Fig. 11-32, the outlet pressure is exerted on the underside of the bellows and on top of the seat disc. Nortek, Inc. is one of the largest global companies you’ve probably never heard of. Nortek, Inc. is the parent company of Nortek Global HVAC, which sells products under major brand... Head pressure hvac, This video explains what determines head pressure in refrigeration systems. Its explained by a Dunwoody College of Technology staff member Tom Kleinman., Fluctuating head pressure, R22, Piston. Looks like non condensables. Noncondensibles for sure, possibly moisture. -Recover all refrigerant. -If you can change the oil in the compressor might be worth it. -Replace Filter drier. -Triple evac If you have the time. -Charge by weight, then check superheat and add what’s needed., Are you looking to take your HVAC skills to the next level? If so, then an HVAC course online might be just what you need. In today’s fast-paced world, online learning has become i..., rmosden, hvacmatt123 liked this post. A cold suction line (low superheat) with low suction pressure is a symptom of low evaporator air. A liquid restriction would result high superheat (warm suction line). The high head probably due to the other guys overcharging, trying to get the suction pressure up., The fan speed controller keeps the condensing pressure at a steady level by regulating the speed of the fan motors. When pressure is declining, the controller decreases the output voltage, changing the speed of fan motor. The proportional band is a non-adjustable pressure difference between max. and min. pressure where the regulation occurs ..., During air conditioning mode, the pressure on the vapor line of an R-410A system will be somewhere between 102 to 145 PSIG. If the system had R-22, the vapor pressure would be between 58 to 85 PSIG but these pressures will be dependent on the wet bulb temperature inside the building and the ambient temperature outside the …, Design conditions and head pressure. High Head pressure for a refrigeration system, including a heat pump or air conditioner can cost you more money and possibly lead to premature failure of the compressor. It can also cause a malfunction in the system that will lead to reduced capacity for cooling and heat (for a heat pump) or the system not ..., 20 psia. 10:1 is a compression ratio commonly found in refrigeration applications. If you are thinking about air conditioning, it is often around 3:1 or 4:1. Example 2: 200 psia = 20:1. 10 psia. In this example, the suction pressure drops by 10 psia, which doubles the compression ratio. At this compression ratio, a compressor designed …, 1. Refrigerant Leakage. One of the leading causes of low suction pressure is refrigerant leakage. When refrigerant leaks occur, the system’s refrigerant charge decreases, resulting in reduced pressure levels. Leaks can occur at various points, including connections, joints, valves, or even within the coils themselves. 2., I have a on going argument, discussion and bet over head pressure. I have two fellow employees, one being a supervisor, that have made the statement numerous times that head pressure was high due to high indoor temperature. They are telling me that at a return temperature of 90 degree F a DX refrigeration system will have a higher head …, Make your influence uniquely far-reaching. If they pulled a vacuum period, and broke the vacuum with R22, then the problem isn't noncondensables. There simply wouldn't be enough air or nitrogen in the system even at 28-29" vacuum to affect the head pressure. The high head pressure is more likely due to an overcharge., R410a min. head pressure. before i ask let me say i am certified in R410a and i work with it almost everyday so please keep that in mind. i was always taught that if it was below 65 oat you have to keep a min. head pressure. what is a min head pressure for 410a? Reply. 02-15-2009, 05:31 PM #2., What are A/C system design conditions while running? 95°F outside, 75°F inside, humidity 50%. T or F - The inside relative humidity adds a significant load to the evaporator coil and must be considered part of the load. True. If the outside temperature increases, what happens to the head pressure and system capacity?, Something I'm wondering, With the phase out of 22,and the new equipment using 410,I am wondering what the head pressures are going to be like and what it will do to that new equipment out here in Death Valley where our high temps reach almost 130. We got off easy this year,our highest temp was 128 and been hovering about 120 most of …, This video explains what determines head pressure in refrigeration systems. Its explained by a Dunwoody College of Technology staff member Tom Kleinman., Mar 1, 2022 · Head pressure is generated by your gas compressor and can be too high or too low depending on the weather, condensing temperature range, and other factors. Learn how to detect, prevent, and repair high head pressure in your HVAC unit with tips from Home Inspection Geeks. , Technically, "head pressure" is compressor discharge pressure. This pressure is formed by compressing superheated refrigerant vapor and discharging the vapor into the condenser. True "head pressure" is measured at the discharge side of the compressor, not at the liquid line service valve such as on most split systems., Totalinefi Head Pressure Controls The Totalinefi P251-0083C Solid State Head Pressure Control Designed specifically for HVAC and Refrigeration applications, the P251-0083C is a temperature-sensitive fan motor speed control which regulates head pressure at low ambients by varying the air volume through the condenser. Its unique construction , In fluid mechanics, pressure head is the height of a liquid column that corresponds to a particular pressure exerted by the liquid column on the base of its container. It may also be called static pressure head or simply static head (but not static head pressure). Mathematically this is expressed as: = = where is pressure head (which is actually a …, Suction pressure, head pressure, subcooling, superheat, Delta T. Taking all five of these calculations into account on every service call is critical. Even if further diagnostic tests must be done to pinpoint the problem, these five factors are the groundwork before more effective diagnosis can be done. I would also add static pressure as an …, In order to correct this R-22 was phased out across the world. Here in America our phase out began in 2010 and the refrigerant will be completely phased out in 2020. Taking R-22’s place is the HFC refrigerant blend known as R-410A, our Puron. As I write this article, in 2019, there are still thousands of R-22 machines out there, but they …, On 2019-01-24 by Rkg1963 - Nordyne heat pump head pressure shuts the system down at 600 in heat mode. Have a 3 ton Nordyne Residential HeatPump Condenser that the head pressure run up around 600 before it shuts down . Only in Heat mode. Pressures look great in Cool mode. Any ideas as to why this is? On 2017-11-01 by David, Apr 27, 2018 ... Welcome to my YouTube channel! For all your business management needs, I highly recommend using Jobber. Whether you're an HVAC professional ..., Pressure in the head and neck. The stress in the nerves and muscles of the neck can cause pain in the head. Sometimes, pressure or pain appears in both the head and the neck. This can be caused by ..., The need for head pressure control. June 1, 2000. There are various methods of head pressure control, some of which contractors may not be aware of. They can have a dramatic effect on the performance of refrigeration systems and components. Refrigeration systems are designed around certain criteria:, Sep 18, 2020 · The main reasons your compressor will have simultaneously low head pressure and high suction pressure is due to: Bad or leaky compressor valves. Worn compressor piston rings. Leaky oil separator return line. Your compressor valves may become inefficient due to poor sealing from dirt and debris deposits. , Various experts and professionals claim that head pressure for a 410A system should be 400 to 418 PSIG on the high side while 120 to 130 PSI on the lower side. Anything more than this range is considered high head pressure. This value may vary a little bit depending on the weather and other external conditions., A compressor may have a discharge pressure of 290.6 PSIG and a suction pressure of 62.3 PSIG. We’d find our compression ratio using the following steps: 1. Add atmospheric pressure to both gauge pressure values to get the absolute pressures. 290.6 PSIG + 14.7 PSI = 305.3 PSIA. 62.3 PSIG + 14.7 PSI = 77 PSIA. 2., April 10, 2023. On any type of refrigeration system, from small reach-in coolers all the way to large chillers, controlling the head pressure of the refrigerant is important. That’s because it helps keep the system operating properly in low ambient conditions — typically below 65°F for air conditioning and 55° for refrigeration systems., A typical pressure control setup is shown in Table 1. Excluding a cold, windy day, where the wind is able to blow through the tube bundle on the condenser, the head pressure would never fall below 160 psig with this control strategy. While this is a simple method of control, it does have a few disadvantages., Troubleshooting Refrigerant Charge to Determine a Bad TXV. If your suction pressure is staying the same while adding refrigerant, and your head pressure is shooting up while the suction pressure is staying the same, your TXV valve is probably bad. If you do your homework and suspect that the TXV bulb lost charge, it’s probably a better idea ..., Restriction in the Refrigerant Flow. Another cause of low suction pressure high head pressure can be a restriction in the refrigerant flow. This can be caused by a blockage in the refrigerant lines or a problem with the compressor, and can lead to low suction pressure and high head pressure. 3. Faulty Compressor., 410A System with high head. I went to do a maintenance on a 410A Trane system today, when I came up on the trane I noticed it was running like a 450 pound head pressure, the first thing i thought was why in the world would it be so high, so I cleaned the cool, checked filters, checked txv bulb position, everything checked out although there ...