and Stand by pressure is 85 to 95 lbs psig . This condition could also be caused by bad motor bearings, defective capacitor, and shrubs or other obstructions around the unit. Hooked up an envirotech 3226 to it using a supco piercing valve and it was -28psi. During operation refrigerant is returning to the compressor from the cooling (evaporator) coil in this line. Also, what causes high suction pressure r22? Pressure that is too much lower or higher shows there is a problem. Forane 134a Pressure Temperature Chart Author: Arkema Inc. Subject: Forane 134a Pressure Temperature Chart Keywords: Forane 134a, R-134a, Pressure Temperature Chart, PT Chart, HVAC, refrigeration, air conditioning, refrigerant gas Created Date: 10/4/2012 11:23:04 AM Moisture in the refrigeration system, problems, and remedy. It looks like this is a post about a domestic appliance - you would be better off asking this question in r/Appliances! Therefore in a normal R134a, the low-pressure side is 90 degrees or less, and the PSI should be close to 30. R134a Pressure Gauge Chart. Minimum normal suction pressure for R134a chiller, http://www.funke.de/files/funke_shell_tube_he_e.pdf, If this is your first visit, be sure to If you didn’t properly weigh in the charge you’re going to have no idea how much volume you actually have in the system. That being said, there are still millions of cars on the road that use R-134a and there will be continue to be for at least another … Suction or, as it is also known, low side pressure, is one of the critical variants in the operation and diagnostic processes of air conditioning and refrigeration. Filled to 0 psi and waited overnight. I totally missed this interpretation of the situation, but it's very likely correct. If your freezer is stable at -2F, the evap coil should be only a few degrees cooler than that, so your low side pressure should really be something like 2-6 PSIG. Most refrigerators built after 1995 typically uses the R134a refrigerant. The low suction pressure with high evap temperature (excessive superheat) suggests a lack of refrigerant. If it's in vacuum, then the superheat is high due to the evaporator being starved. Your suction pressure will drop as the load does. You’re simply stabbing in the dark at this point. Remember that as the freezer temp drops well below zero, the suction pressure will go into vacuum and this is expected. Long story short, 15 year old Samsung french door refrigerator. Used 1/6 - 1/5 can of 12oz r134a. It should never be negative. Also, you gain in capacity with higher subcooling. Similarly, at the highest temperature, 60−20 = 40 degrees Fahrenheit, the coil should run at 57 psi. New comments cannot be posted and votes cannot be cast, More posts from the refrigeration community, Questions, discussions, and stories related to the Commerical and Industrial Refrigeration industry, Press J to jump to the feed. If you can fix the leak great, but dont forget a new spun driver. The most common cause of low condenser air flow is a dirty coil. Hello all- Back on this big old boat with another fridge type question. this is the pressure in the air conditioner's refrigerant suction line (low side pressure during compressor operation) and this will be a relatively low number, often less than 100 psi. secondly isobutane is a bigger compound. Many servicemen experience service calls where the compressor has both a low head pressure and a high suction pressure. The high head probably due to the other guys overcharging, trying to get the suction pressure up. Did it drop because the system got cold? When compressor is at room temperature then stand by pressure is 50 to 60 lbs psig. Suction pressure low - Low superheat at evaporator outlet. We're using 12 oz cans of R134a. If not It may not be worth calling in a professional unless the fridge is worth a couple grand. This script determines the gas pressure based on temperature of R134a refrigerant. Ambient Temperature (°F) We've added 1 and 1/2 cans so far. The high pressure line coming off the compressor is hot so I guess the compressor is working. If that doesnt work you'll have to cut into the system to put ports in to see what's going on. Compressor oversized and the evaporator is undersized. On a properly working system, high-side pressure will be about twice the ambient temperature, plus 50 PSI. If the low side pressure rises to over 10 psig, the system has too much refrigerant. We literally haven’t moved it in 5 years so, not sure what would cause it to leak. I would recover the charge the try to free the restriction with a heavy charge of rx-11 and nitrogen. That way, you can use evaporator superheat as low as possible, and total superheat as required by Bitzer. Every Refrigerator have different size of Compressor when we charge Gas then Some Refrigerators Ready on zero (0 PSI) Running Pressure and some refrigerators ready on 15 PSI Running Pressure. If you show a vacuum on startup, dump in freon and still show negative pressures, then there is a restriction somewhere. After I added more to get it to 0, the suction line is now covered in frost. Piercing valves are never supposed to be left on a system and they most definitely leak. But the low air problem would result in high head pressure in the heat cycle. The result is lower superheat, high suction pressure, high discharge pressure and lower sub-cooling. Suction pressure or Back pressure of R 134a is 0 to 5 lbs psig. No way anyone can reliably tell you what’s going on without knowing exactly how much refrigerant (in ounces or grams) you put in. Usually the bottom rows of the evaporator will freeze up when this occurs. Headpressure is 150 to 185 lbs psig. Use the hex-head wrench to turn the piercing valve, found in the center of the top half of the saddle … Poor distribution of refrigerant thru the evaporator nozzle and circuits. An extremely high discharge pressure coupled with an extremely low suction pressure is an indicator of a refrigerant restriction. As a low-pressure refrigerant system, the R134a is used in most home refrigerators as it is very effective and convenient for high-temperature applications. Evaporator starving of refrigerant and … I would advise (if it is possible) to install suction line heat exchanger in order to increase subcooling and total superheat. If you are using a low pressure gauge when the low pressure reading is between 25 psi and 40 psi, the system is fully charged. For cooling coil temperature -14 to -16 degree Celsius. You can use those numbers to calculate superheat and get a clearer picture of what’s going on. Press question mark to learn the rest of the keyboard shortcuts, ‍ Deep Fried Condenser (Commercial Tech). Pull a good deep vacuum and then weigh in charge. I am a bot, and this action was performed automatically. Often, the refrigeration equipment is still running, but the product temperature is suffering about 7 to 10°F. kenmore model #253.23024102 serial #wb40836697 hot gas coil in condensate collector was leaking repaired leak evacuated system but had no way to weigh 6.5 oz charge .unit is at 13 degrees with suction line icing up I am retired hvac tech but am not familiar with r134a Would recommend pulling refrigerant, brazing in ports high and low. What is suction discharge pressure for r134a? The recommended pressure for a home refrigerator using R134A refrigerant is between 2 psig and 150 psig. Could it be leaking from the bullet piercing valve? 2(d). It seems that it's still under-charged. Remember, there are two sides to the chart; we have the low and the high. You need to find and repair the leak before you charge it. Waited 24 hours and checked today again by hooking up the envirotech discharge hose to the supco bullet piercing valve and it showed -8psi. P.s. I've been reading through these comments wondering where this one was. Having gone through all the above details, you are still wondering, When the compressor kicks in, the suction against the restricted orifice will cause the compressor to quickly cycle out. It's the difference between freezer temp and boiling refrigerant temp (from the PT chart) which gives you some information about how much liquid is in the evap. If you have the equipment that is. Please contact the moderators of this subreddit if you have any questions or concerns. What is the lowest normal operating suction pressure that is acceptable on R134a chiller running water with no glycol or other low temp additives? The low suction pressure with high evap temperature (excessive superheat) suggests a lack of refrigerant. ~630 gpm chilled water flow with an evaporator inlet temperature of 46-55 degrees depending on the load. Told the fridge to keep the freezer at -12 but it’s holding -2f (using a thermometer). In that case shut it off for a day and see if the oil will migrate back to the compressor. So I refilled from -28 to 0 yesterday. As a result of marginally higher discharge pressure and lower suction pressure for R134a, the frictional losses in the R134a are marginally higher, as shown in Fig. The R134a is a popular refrigerant used in a variety of modern refrigeration and air conditioning applications. check out the. By Alec Johnson May 25, 2019. High pressure side is high, low pressure side (suction pressure) is low: Discharge pressure is very high after turning on the A/C switch, and bubbles are seen in the sight glass (if charge valve is located after R/D, discharge pressure is unknown)-----Choking between compressor and R/D: Remove clogged materials, or replace condenser This chart details how ambient temperature correlates with the system refrigerant charge pressure, and how it affects high and low side psi readings. EDIT: u/chefjeff1982 correctly notes that this may be a restriction on the high side, like a clogged cap tube, rather than being under-charged at all. We are operating a 280 ton R134a chiller using a 45 deg F evaporator leaving temperature setpoint. Then look for a leak if you have one. This is a good point. Fig. 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. Although the low side pressure should be around 2 psig, at times it can fluctuate from 0 to -3 psig. I appreciate the nod. Production of chlorofluorocarbons (CFCs) has been phased out. Evaporator coil is icing. Of course, your system is leaking and will not stay functional in the long run unless you find and fix the leak - at which point you get to weigh in a proper full charge and don't have to guess at it. R-134a is the most common refrigerant found in automobiles today. Especially when pulling down from almost room temp. A cold suction line (low superheat) with low suction pressure is a symptom of low evaporator air. Checked today and it’s at -10 (freezer at -2 woohoo, fridge at 40, even though I set it to 34). it's worth noting that this is probably a cap tube system and could very well have a stopped up cap tube. Unlike traditional refrigerants, the R134a is applicable and … For a high pressure gauge when the high pressure reading is 200 to 225 psi for R12 or 225 to 250 psi for 134a, the system is fully charged. It can be used for recharging refrigerant, or to diagnose an a/c system based on pressure readings from your gauges. High and low side pressures are pretty close to R134a vapor pressure for temps of the lines … do a pressure test with nitrogen for at least a couple hours. The pressure for an ordinarily operating R134a is between 22 and 57 pounds per square inch (PSI). A liquid restriction would result high superheat (warm suction line). With 134a, a low-side pressure of 0 PSIG means your boiling liquid is at -15F. The low-side should be near 30 PSI at 90 degrees Fahrenheit or less. Suction pressure is a term used to describe the pressure of a refrigerant gas at the intake point of a refrigerator or air conditioner compressor. I'd keep slowly adding refrigerant an ounce at a time until the freezer stabilizes at a nice low temperature with a reasonable superheat. R134a Refrigerant Running Pressure Normal Refrigerators. Iso butane is R600a, when you compare the change of temperature with pressure the change is drastic in the case of iso butane than in R134a. Fridge section stayed at 38 but freezer was 62. If it's not leaking, it's restricted. Especially on these little refrigerators. R134a Refrigerant mostly use for Refrigerators. With 134a, a low-side pressure of 0 PSIG means your boiling liquid is at -15F. It has been in use since the early 1990’s and now, in 2019, we are beginning to see it’s popularity wane with the rise of the new HFO refrigerant known as R-1234yf. The table below shows the comparison between temperature and pressure for R134a. If your freezer is stable at -2F, the evap coil should be only a few degrees cooler than that, so your low side pressure should really be something like 2-6 PSIG. The system should be recovered, vacuumed (min 20 minutes) and charged. No this is aimed at hvac / appliance techs. What is the lowest normal operating suction pressure that is acceptable on R134a chiller running water with no glycol or other low temp additives? The gauges readings will depend on the ambient temperature. I vacuumed the system down and went to charge, but found only a low pressure port. R-134a TEMPERATURE PRESSURE CHART (Tabla de Temperaturas y Lecturas) Ambient Temperature °F / °C (Temperatura Ambiental) Low-Pressure Gauge (Puerto de Servicio del Lado de Baja Presion) High-Pressure Gauge (Puerto de Servicio del Lado de Lado de Alta Presion) 65°F (18°C) 25-35 psi / 172-241 kPa: 135-155 psi / 931-1069 kPa: 70°F (21°C) 2(a) and 2(c) also show that R134a has a higher final discharge pressure and temperature. A restricted orifice will usually show as very low suction side pressure and lower than normal high side pressure. After compressor disengagement, the rise in suction side pressure will usually be very slow. With the A/C turned OFF - On a cold day the pressure will be low, on a hot day the pressure will be high. Remove piercing valve and patch. Readings that are higher or lower indicate an overcharged system. You do not have enough refrigerant in the system with r134a at 0 psi. So as your fridge cools down, some pressure drop is expected. Or am I losing refrigerant? Any chance you can take a temperature of the suction line and your pressure at the same time. Table 1: R134a Saturation Properties pressure table (Reference: www.chemours.com) Back to the problem at hand. I always weigh my refrigerant into systems that way I know for sure if it is a leak and not a restriction. There is absolutely a restriction, most likely cap tube/strainer. If the designer of the unit wanted to achieve -10F in the freezer case, they would design for 2 or 3 PSIG on the suction side at that cabinet temperature. With too little flow through the metering device, the refrigerant will all get condensed and stored in the high side of the system and suction pressure will go low no matter what the freezer temp or charge level is. This is a likely explanation for the problem. We have an ice maker that uses 134A gas. Get shopping advice from experts, friends and the community! These calls are tough to handle because the compressor is still cooling, but not cooling to its rated capacity. R1234yf is about 18% lower than that of the R134a, as shown in Table 1. I’ve done mini splits but never refrigerators until mine went out. I would throw it in the trash to be honest but if you insisted on fixing it. But for real throw it in the trash. Your system has a leak. Light load conditions. There is a pressure drop but even at freezing it should be nowhere near zero. If I couldnt clear it I would change it. Environmentally acceptable replacement compounds are therefore needed for use in existing medium and low temperature refrigeration applications. The boiling temp of R134A is -15 degrees F at 1 bar absolute pressure. But initially running -28 psig seems very, very low. I had to fix a leak and thus started with an empty system.