Low suction pressure high head pressure

The SC might be normal , but the normal head for a r410 system w/ a 68* ambient should be closer to 300psi and the normal suction press should be closer to 110psi w/70* IDB. Those p/t's sound more like r22. kdean1, buttwheat liked this post. As others have said it sounds like a TXV and maybe low on juice.

Low suction pressure high head pressure. The low side pressure of a typical R410A mini split is between 110-140 psi depending on the operating conditions. Though it can vary, the low side pressure of a mini split should not fall below 100 psi or raise beyond 160 psi. The working pressure of mini splits is depending on factors such as the weather and cooling load.

Connecting the low pressure side to the suction side of the compressor helps in sucking out the excess pressure from low side AC. c. Close the Service Valve Before Releasing Pressure. You can use a hex key or a wrench to close the service valve on the high-pressure side but don’t close it entirely. d.

Typical low pressure or suction side pressure for R410A is about 120 psi, varying by ambient temperature, here assuming 75°F, may vary by equipment and metering …Jul 25, 2011 · High discharge temperatures can indicate minimal movement of refrigerant. Because the refrigerant isn't being pumped at design rates it stays in the condenser for a longer period of time and is cooled more, hence lower head pressures, and in turn, if the compressor is not pumping well, you will see elevated suction pressures. Reply. Sometimes, however, problems will occur and this will include anything from low suction pressure to low compressor discharge pressure. High compressor discharge pressure will also be a problem that needs to be attended to right away. Basically, a discharge pressure is the pressure that is being generated on a gas compressor’s output side ...Low blood pressure, or hypotension, is generally not a concern and requires no treatment in healthy people, according to WebMD. Treatment of hypotension may require treatment of an...The suction pressure, also known as the low-side pressure, for a 404A cooler typically falls between 55-70 psi. This pressure ensures that the refrigerant evaporates at the desired temperature in the evaporator, providing efficient cooling. ... What causes high head pressure on a walk-in cooler? High head pressure in a walk-in cooler can be ...Although cryptos enjoyed strong performances earlier, a lack of fundamental catalysts may apply some pressure on the sector. The fiat alternative narrative isn’t quite panning out ...I have a suction pressure of 70, converted temp of 41, suction line temp of 51, head pressure of 250, converted temp of 117, head line temp of 96. Air entering condenser is 82 and exit is 100. Air entering evaporator is 76 and exiting is 52.When it comes to building a deck, there are many options available. One of the most popular places to shop for decking boards is at Lowes. Lowes has a wide selection of decking boa...

Manitowoc model SD0592N remote condenser R404a Got called for no ice checked machine found suction pressure 140 and high pressure 250 , no cooling to plate can not figure out what is causing the high pressures. Maybe bad headmaster on remote condenser but it so 500psi on valve. any suggestions would be appreciated.problems. Fluid flows from areas of high pressure to areas of low pressure. Pumps operate by creating low pressure at the inlet which allows the liquid to be pushed into the pump by atmospheric or head pressure (pressure due to the liquid’s surface being above the centerline of the pump). Consider placing a pump at the top of the mercury Number 2 is incorrect, metering device part depends on system to system. High load is correct. Look at your liquid line temps, subcooling and approach temps. They will help diagnose high head issues. There is another cause of high head pressure, mismatched (higher btu) compressor. Different refrigerant in the system. Scroll Troubleshooting Solution Chart - Copeland A/C Specific. Deep Vacuum Conditions. Deep vacuum can cause arcing damage to the Fusite pins. Models built after September 1991 have an internal vacuum protection and stop pumping when the pressure exceeds approximate. 10:1. Scroll compressors should never be used to evacuate a system, allowed to ...This low head pressure and higher-than-normal evaporator pressures will decrease the compression ratio of the compressor, causing high volumetric efficiencies. This will increase the pumping rate of the compressor, and a balance may be reached if the compressor can keep up with the high refrigerant flow in the evaporator.Any time there is saturated liquid and vapor together, as in the condenser and evaporator, there will be vapor pressure present. Vapor pressure acts equally in all directions and affects the entire low or high side of a refrigeration system. As pressure increases, saturation temperature increases. As pressure decreases, so does saturation ...

Any time there is saturated liquid and vapor together, as in the condenser and evaporator, there will be vapor pressure present. Vapor pressure acts equally in all directions and affects the entire low or high side of a refrigeration system. As pressure increases, saturation temperature increases. As pressure decreases, so does saturation ...How to Fix Low Suction Pressure Issues. If there is excessive moisture in system: replace the drier. If you find a flattened or kinked hose: replace the hose. If the compressor pistons have worn out: replace the compressor. If there is a shortage of refrigerant: add refrigerant. If there is a leaking compressor head gasket: replace the head gasket.This will cause the following symptoms: Low evaporator (suction) pressure; High evaporator and compressor superheats; Low compressor amp draw; Short-cycling on the low-pressure control; Somewhat high discharge temperature; Low condensing (head) pressure; Low condenser split; and.This will cause low suction pressures, high superheats, low amp draws, and low head pressures. Also, the symptoms of a restricted TXV system are very similar to a system with a refrigerant undercharge. However, the undercharged system will have low subcooling levels. Technicians often confuse an undercharged system with a restricted metering ...

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Took a reading off one of our units that cool an elevator machine room. It's an old Carrier 10 ton unit, single compressor, water cooled tube in tube condenser. Suction pressure was good at 68 , head pressure went over 300 and was tripping it out. Cleaned the strainer, same thing happens. Brought in a mechanic who says the TEV is bad and is …In the cooling mode, running in outdoor temperatures below 55 degree without a "low ambient control' will cause symptoms very similar to low refrigerant. The cold outside air will cause the head pressure to drop which, in-turn, causes the suction pressure to drop. Try blocking part of the outdoor fan discharge to increase head …Typical low pressure or suction side pressure for R410A is about 120 psi, varying by ambient temperature, here assuming 75°F, may vary by equipment and metering controls. 3. Typical high side pressure for R410A is < 600 psi at an ambient outdoor temperature of 95 °F, may vary by equipment. 4.Number 2 is incorrect, metering device part depends on system to system. High load is correct. Look at your liquid line temps, subcooling and approach temps. They will help diagnose high head issues. There is another cause of high head pressure, mismatched (higher btu) compressor. Different refrigerant in the system.Discover expert tips for troubleshooting well water issues, including low pressure and discoloration. Keep your water flowing smoothly with practical solutions. Expert Advice On Im...

Greetings, I am working on a R22 Lennox Split Heat Pump 3 ½ ton. The unit will trip on the compressor relief valve in heating. I was unable to test the unit S/C and S/H accurately, due to the High Side pressure building up so fast with in a minuet will be hitting 400psi and blow the low side would sit at about 50psi. I tested the RVR from cooling to …Suction Head. Based on the Energy Equation - the suction head in the fluid close to the impeller *) can be expressed as the sum of the static and velocity head: h s = p s / γ liquid + v s 2 / 2 g (1) where. h s = suction head close to the impeller (m, in) p s = static pressure in the fluid close to the impeller (Pa (N/m 2), psi (lb/in 2))An over-charged system will cause efficiency problems and can cause component damage, but the most obvious sign of an over-charge in heating mode, is that it will trip on high head pressure. Jeff Rosenblum. Technical Support. 16 Years Industry Experience. Cell (330) 962-2491.Jul 25, 2011 · High discharge temperatures can indicate minimal movement of refrigerant. Because the refrigerant isn't being pumped at design rates it stays in the condenser for a longer period of time and is cooled more, hence lower head pressures, and in turn, if the compressor is not pumping well, you will see elevated suction pressures. Reply. 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 …May 8, 2017 · Table 1: R134a Saturation Properties pressure table (Reference: www.chemours.com) Back to the problem at hand. For any refrigeration cycle/AC unit there are two operating pressures: suction pressure and discharging pressure, high and low settings for each pressure line determined by the manufacturer will stop the unit. Suction Head. Based on the Energy Equation - the suction head in the fluid close to the impeller *) can be expressed as the sum of the static and velocity head: h s = p s / γ liquid + v s 2 / 2 g (1) where. h s = suction head close to the impeller (m, in) p s = static pressure in the fluid close to the impeller (Pa (N/m 2), psi (lb/in 2))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 ...In the cooling mode this will result in low suction pressure and low discharge pressure. Sub cooling would be extra high. However, heatpumps can't always be charged accurately using sub cooling alone. Usually "a stuck check valve" can be freed-up by using a strong magnet.Suction head = h s = p s / ρg + v s2 / 2 g. From the definition of vapor pressure head, Vapor pressure head = h v = p v / ρg. In the simplest language, we can say, NPSH = Pressure head at the inlet or suction – vapor pressure head. Let’s see the formula or equation of NPSH, NPSH = hs – hv.Sometimes, a system might have less resistance to flow than expected, allowing the pump to operate at a higher flow rate and lower pressure. Conversely, if you are measuring pressure in a section of pipe away from the pump, at a higher elevation, or after a flow obstruction, there will be a pressure drop; therefore, pressure will be lower than ...

Number 2 is incorrect, metering device part depends on system to system. High load is correct. Look at your liquid line temps, subcooling and approach temps. They will help diagnose high head issues. There is another cause of high head pressure, mismatched (higher btu) compressor. Different refrigerant in the system.

If you have high blood pressure or heart, liver, or kidney problems, your health care provider may suggest you lower your sodium intake. Look for these words on labels: low-sodium,...Low suction pressure in both mode. b. High head pressure in both mode. c. Low head pressure in the heat mode and high suction pressure in the cool mode. d. High head pressure in the heat mode and low suction pressure in the cool mode. D. If the reversing valve were to stick in the halfway position, which one of the following would the service ...Choose from our selection of high pressure water pumps, including air-powered constant-flow-rate pumps, gasoline-powered water-removal pumps, and more. ... Maximum Feet of Head. 98 ft. 100 ft. 103 ft. 110 ft. 115 ft. 125 ft. 3,679 ft. ... Pumps are self-priming, which means they create a suction force to draw liquid upward to fill the pump ...This restriction will result in a pressure drop across the restriction. You'll have higher pressure on the inlet side and lower pressure on the outlet side of the “traffic jam.” ... we will see low suction pressure, high superheat, and normal to high subcooling. (Note: high head pressure isn't typically an indicator of a restriction!) In ...High suction pressure plus low head pressure can risk product quality and safety. By John Tomczyk. FIGURE 1: A normal valve plate with suction and discharge valves. ... High Evaporator (Suction) Pressure — Refrigerant vapor will be drawn from the suction line into the compressor’s cylinder during the downstroke of the compressor. …Peal. 3 posts · Joined 2009. #46 · Jul 12, 2009 (Edited) I think bwalley is correct. 3 things will cause high head pressure; poor air flow across condenser, overcharge, or non condensable in system. Recover charge, check system for leaks, pull vacuum, and weigh in new charge.Jack Ma's Ant Group and Alibaba have come under increasing regulatory pressure from Chinese authorities in recent months. Jump to Alibaba jumped as much as 5% on Tuesday after CNBC...Apr 28, 2005 · Any time there is saturated liquid and vapor together, as in the condenser and evaporator, there will be vapor pressure present. Vapor pressure acts equally in all directions and affects the entire low or high side of a refrigeration system. As pressure increases, saturation temperature increases. As pressure decreases, so does saturation ... Sometimes, a system might have less resistance to flow than expected, allowing the pump to operate at a higher flow rate and lower pressure. Conversely, if you are measuring pressure in a section of pipe away from the pump, at a higher elevation, or after a flow obstruction, there will be a pressure drop; therefore, pressure will be lower than ...

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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.Greetings, I am working on a R22 Lennox Split Heat Pump 3 ½ ton. The unit will trip on the compressor relief valve in heating. I was unable to test the unit S/C and S/H accurately, due to the High Side pressure building up so fast with in a minuet will be hitting 400psi and blow the low side would sit at about 50psi. I tested the RVR from cooling to …Scale results in a low head pressure in the cooling mode and high suction pressure in the heating mode. False. A domestic hot water loop is loop is often used for heating domestic hot water from the hot discharge gas coming from the heat pump's refrigerant compressor. True.In addition to a malfunctioning TXV, other factors that can cause high subcooling include a dirty condenser coil or restricted airflow over the condenser. Low Suction pressure/ low head pressure. A bad TXV can also cause low suction pressure and low head pressure in an HVAC system by restricting the flow of refrigerant into the …Suction Head. Based on the Energy Equation - the suction head in the fluid close to the impeller *) can be expressed as the sum of the static and velocity head: h s = p s / γ liquid + v s 2 / 2 g (1) where. h s = suction head close to the impeller (m, in) p s = static pressure in the fluid close to the impeller (Pa (N/m 2), psi (lb/in 2))Failed suction pressure transducer (SPT) Replace. No evaporator air flow or restricted air flow. Section 7.11. Excessive frost on evaporator coil. Section 6.6. EEV control malfunction. Section 7.14. Loose or insufficiently clamped sensor (ETS) Replace. High suction pressure with low su­perheat. Foreign material in valve. Section 6.11Second, the pump curve for the 14.125-inch impeller shows that the pump's shutoff head is 212 feet, a 16-foot head increase over the normal pump head of 192 feet at 1,000 gpm. A fluid density of 62 pounds per cubic foot (lb/ft 3 ) would result in a pressure increase of 8.6 pounds per square inch (psi), which is less than the observed 16 psi ...My suction is running at 45psi and head is at 110psi. I checked evap coil and filter and both were clean, so I figured it was low on R22. I added 7 lbs. (factory charge is 7.25 lbs) and pressures did not change. The suction line is frosting up to the compressor. I'm starting to think I have a bad reversing valve. We would like to show you a description here but the site won’t allow us. Low suction/low head pressures. Bevearage air Prep table not cooling-. R134a, AEA4440YXA hermetic. pressures were about what they should be for a cap tube system (roughly 150/25 psi) but just blowing around warm air. Plate said 7 oz of R134A but I pull out 2 lbs so I evacuate and recharge with 7oz and now the pressures are way down.High head suction pressure. High suction pressure is a common problem in the cooling systems. It can cause due to improper functioning of the compressor. If the compressor is not delivering sufficient refrigerant to the system, the suction pressure will increase accordingly. One can understand the high head suction pressure with a better study ...So we replace the compressor (same model #), replace the liquid line filter dryer, and evacuate to 500 microns. I weigh the charge in per the manual = unit's orignal charge + addl ounces per foot of lineset - total of 5# 6 oz. Start unit up, damn it, looks wrong immediatelY: Suction: 149.5 psi. Suction Temp: 55.4*F. ….

normal suction low head pressure. im in the field 3 years now and this is the first time ive come across this. residential split system 1.5 tons and i had a good suction pressure but my head pressure was super low, only 150-160. the strange thing is operations seemed pretty normal. cold suction line, warm liquid line, condenser was …May 8, 2017 · Table 1: R134a Saturation Properties pressure table (Reference: www.chemours.com) Back to the problem at hand. For any refrigeration cycle/AC unit there are two operating pressures: suction pressure and discharging pressure, high and low settings for each pressure line determined by the manufacturer will stop the unit. How to Fix Low Suction Pressure Issues. If there is excessive moisture in system: replace the drier. If you find a flattened or kinked hose: replace the hose. If the compressor pistons have worn out: replace the compressor. If there is a shortage of refrigerant: add refrigerant. If there is a leaking compressor head gasket: replace the head gasket.lower suction pressure and high discharge pressure. Study with Quizlet and memorize flashcards containing terms like which of the following is NOT a symptom of a hermetic system that is low on refrigerant?, frost on the suction line indicates;, an increase in head pressure causes _____ refrigerant to flow through a capillary tube. and more.Head pressure, or high-side pressure, is crucial in HVAC units, particularly for the efficient function of the air conditioner’s condenser. Maintaining proper refrigerant …When it comes to building a deck, there are many options available. One of the most popular places to shop for decking boards is at Lowes. Lowes has a wide selection of decking boa...An R-22 evaporator running at 40F saturation temperature will have a corresponding pressure of 68.5 psig. Should the suction pressure drop below 57 psig, the coil temperature will drop below 32F causing moisture in the air to freeze on it (see Figure 4) causing no end of trouble. A R-410A evaporator running below 100 psig will freeze-up just ...Low suction pressure causes. low suction pressure is developed in the refrigeration system. Some of the most probable causes are as below, The coil is covered with dust or frost. Restriction in the refrigerant line. Filters and strainers are dirty. Faulty fan motor. Low room temperature. Faulty compressor. Low suction pressure high head pressure, Head pressure, or high-side pressure, is crucial in HVAC units, particularly for the efficient function of the air conditioner’s condenser. Maintaining proper refrigerant …, Low suction pressure and high head pressure occur when there’s a drop in refrigerant pressure in the AC system, coupled with elevated output pressure in the compressor. The primary culprit behind this condition is a …, A few months ago A/C repair company found high suction pressure & low head pressure. Replaced a valve in air handler. System is a 2 y/o, 5 ton Trane heat pump. This spring a/c doesn't seem to be cooling the house well. A different A/C company tells me my pressures are way off and shows me a bad valve that should be replaced., goodman heat pump low superheat, high head pressure. first things first, i am pretty new to this so go slow. here's where i am at. outdoor compressor goes into some kind of lockout overnight in winter. 2.5 ton goodman heat pump gsz130301ae. r-410a. piston metering device indoor and outdoor. bought gauges and temperature probes to try to ..., Suction Head. Based on the Energy Equation - the suction head in the fluid close to the impeller *) can be expressed as the sum of the static and velocity head: h s = p s / γ liquid + v s 2 / 2 g (1) where. h s = suction head close to the impeller (m, in) p s = static pressure in the fluid close to the impeller (Pa (N/m 2), psi (lb/in 2)), 💐👌🤝Air conditioner head Pressure low, & Head pressure High & Suction pressure Low what’s Problem How many types problem creating learn very useful informa..., When it comes to building a deck, there are many options available. One of the most popular places to shop for decking boards is at Lowes. Lowes has a wide selection of decking boa..., How to Fix Low Suction Pressure Issues. If there is excessive moisture in system: replace the drier. If you find a flattened or kinked hose: replace the hose. If the compressor pistons have worn out: replace the compressor. If there is a shortage of refrigerant: add refrigerant. If there is a leaking compressor head gasket: replace the head gasket., The human heart creates a pressure within the circulatory system every time it beats. Some people experience periods where their blood pressure is too high or too low. When blood M..., Low suction/low head pressures. Bevearage air Prep table not cooling-. R134a, AEA4440YXA hermetic. pressures were about what they should be for a cap tube system (roughly 150/25 psi) but just blowing around warm air. Plate said 7 oz of R134A but I pull out 2 lbs so I evacuate and recharge with 7oz and now the pressures are way down., higher head pressure and higher subcooling. When any refrigeration system is low on refrigerant it will usually have: low suction and low head pressure. What can cause high superheat in a TEV metered evaporator? ... What combination of symptoms only occurs on a unit with an inefficient compressor? Low head pressure and high suction pressure ..., Table 1: R134a Saturation Properties pressure table (Reference: www.chemours.com) Back to the problem at hand. For any refrigeration cycle/AC unit there are two operating pressures: suction pressure and discharging pressure, high and low settings for each pressure line determined by the manufacturer will stop the unit., A ratio of head pressure to suction pressure is your compression ratio. Higher compression ratios tend to lead to reduced compressor performance (moving fewer BTUs). Even though we tend to see high head pressure as the main problem to avoid, we should be aware that low head pressure is possible., Pressure gauges provide readings of the condensing and suction pressures, allowing technicians to monitor and adjust the head pressure as needed. B. Measuring Head Pressure in Refrigeration Systems To measure head pressure in refrigeration systems, technicians connect pressure gauges to the service ports on the high and low sides of the system., 1 Answer. Hi, High head and a low suction pressure can indicate a couple of different things. One, condenser coil very dirty and needs to be washed very well. This will bring your head pressure down but let it run back up to normal engine temperatures. If the head is ok after you clean it, and suction is even lower, you may still be low on charge., The most fundamental difference between high and low-pressure systems is the movement of air. In high-pressure systems, air descends toward the ground, resulting in stable atmospheric conditions. In low-pressure systems, air rises, leading to more unstable atmospheric conditions. Air also always moves from high pressure to …, Typical low pressure or suction side pressure for R410A is about 120 psi, varying by ambient temperature, here assuming 75°F, may vary by equipment and metering controls. 3. Typical high side pressure for R410A is < 600 psi at an ambient outdoor temperature of 95 °F, may vary by equipment. 4., When it comes to upgrading your shower experience, one of the key factors to consider is water pressure. If you’re looking for a high-pressure shower, you might be torn between cho..., Jul 9, 2019 · we note (and you probably know better than I) that making sense of any refrigerant pressure reading requires also a note of the ambient temperature. If we take 75°F as an example point, R410 low side typical pressure would be about 120 psi and the high side between 410-420 psi. Your high side is a little low. , Failed suction pressure transducer (SPT) Replace. No evaporator air flow or restricted air flow. Section 7.11. Excessive frost on evaporator coil. Section 6.6. EEV control malfunction. Section 7.14. Loose or insufficiently clamped sensor (ETS) Replace. High suction pressure with low su­perheat. Foreign material in valve. Section 6.11, R-22 Low Side Pressure 2: R-22 High Side Pressure 3 °F 1 °C: psig: kpa: Bar-50° ... Typical low pressure or suction side, may vary by equipment and metering controls - these are "gauge pressure readings" or "psig" Typical high …, Feb 25, 2004 · This will cause low suction pressures, high superheats, low amp draws, and low head pressures. Also, the symptoms of a restricted TXV system are very similar to a system with a refrigerant undercharge. However, the undercharged system will have low subcooling levels. Technicians often confuse an undercharged system with a restricted metering ... , Dec 20, 2023 · A blockage causes high head pressure while suction pressure remains low. This imbalance puts strain on the compressor and reduces cooling efficiency. To troubleshoot, technicians will check for dirty filters, malfunctioning expansion valves, and debris in condenser coils. Clearing these blockages restores proper function to the refrigeration cycle. , 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., Basically, any system with a receiver needs to be charged up by ensuring that the receiver is filled up to it's proper level. This "proper level" depends on what type of low ambient head pressure control it has. Can't really go by superheat or subcooling or pressures or SAT. Hope this helps a little bit. Good luck., High Head Pressure. High head pressure is typically accompanied by a low suction pressure. This combination can be indicative of restricted refrigerant. Essentially, this means that air and vaporized water travel through your HVAC’s evaporator until they get to the top of the compressor, where it remains because it will not condense., Typical low pressure or suction side pressure for R410A is about 120 psi, varying by ambient temperature, here assuming 75°F, may vary by equipment and metering …, To diagnose a bad TXV, look for: Low evaporator pressure. High evaporator and compressor superheats. Low compressor amp draw. Short cycling on the low-pressure control. Higher than normal discharge temperatures. Low condensing pressure. Low condenser split. Normal to high condenser subcooling., What causes high suction pressure 404a? High suction pressure in a 404A system can be attributed to several factors. Overfeeding the evaporator, a dirty or blocked condenser, or an overcharged system can all lead to increased suction pressure. Additionally, if the walk-in cooler or freezer is frequently opened or has a high product load, it can ..., An over-charged system will cause efficiency problems and can cause component damage, but the most obvious sign of an over-charge in heating mode, is that it will trip on high head pressure. Jeff Rosenblum. Technical Support. 16 Years Industry Experience. Cell (330) 962-2491., goodman heat pump low superheat, high head pressure. first things first, i am pretty new to this so go slow. here's where i am at. outdoor compressor goes into some kind of lockout overnight in winter. 2.5 ton goodman heat pump gsz130301ae. r-410a. piston metering device indoor and outdoor. bought gauges and temperature probes to try to ..., Aug 1, 2013 · The high head leads to poor heat rejection and the higher pressures can force more of the available refrigerant into the evaporator and show up as normal or high suction pressure with normal or low superheat. Also make sure the outdoor fan motor is running in the proper direction. Reply. , How to Fix Low Suction Pressure Issues. If there is excessive moisture in system: replace the drier. If you find a flattened or kinked hose: replace the hose. If the compressor pistons have worn out: replace the compressor. If there is a shortage of refrigerant: add refrigerant. If there is a leaking compressor head gasket: replace the head gasket.