Low subcool high superheat

Low suction pressure, high superheat, and high subcooling. 20 of 60. Term. The system capacity of an air conditioner with a fixed metering device: ... Low suction pressure, high superheat, and high subcooling. Drops in pressure and temperature. Increases the static pressure drop across the coil.

These are my readings 296psi high side, 95.8 lstat, 93.6 line temp, 2.3 subcool. 140.6psi low side, 50.1 vstat, 51.3 line temp, 1.2 superheat. 20degree delta tee across the return and supply. I may have missed something somewhere, but all that looks like an overfeeding TXV. 50˚ saturated suction pretty much eliminates low airflow, particularly ...Buy HIATSU Digital Manifold Gauge HVAC Refrigeration Heavy Duty with 2 Wired Temperature High Low Side Pressure Measurement Superheat Subcooling 3 Hose Refrigeration Support 88 Types of Refrigerants: Air Conditioning Line Repair Tools - Amazon.com FREE DELIVERY possible on eligible purchasesBryan with HVAC School goes over AC pressures, subcooling, and superheat in his troubleshooting mindset presentation from the BTrained HVAC training event in...Introductory to superheat and subcooling with TXVThere is much more involves but this lets you look how superheat and subcooling is affected by the operation...ant type used. The difference in temperature is the subcooling value. Note: Condensing temperature is derived from using the PT chart. On new refrigerant blends with high temperature glide, this is called the bubble point (BP) temperature. See Figure 2. To measure subcooling with an 80PK-8 Pipe Clamp, allow the system to run long enough for

Low superheat. Meaning? High subcooling meaning? Low subcooling meaning? Reply . 05-13-2015, 08:13 PM #2. Scott Kline. View Profile View Forum Posts View Forum Threads Professional Member Join Date Jan 2014 Location Pennsyltucky Posts 1,643 Post Likes Likes (Given) 1143Superheat is high. How is charge? Low. Subcool is low. How is charge? Low. Comp amps are low. How is charge? Low. Delta T is low. How is charge? ... How is charge? Over. Superheat is high. How is charge? Over. Subcool is high. How is charge? Students also viewed. Abbréviation Autorisation ATC. 88 terms. alexmblanchet. Pubs Test Review. 31 ... Here is a chart that contains low superheat causes and low subcooling causes: Indoor airflow (CFMs) is too low. Oversized AC unit. Outdoor airflow is too low (or condenser coils heat exchange is impeded). High refrigerant charge (overcharged AC unit). Metering device (TXV, AEV, or piston) is overfeeding. May 19, 2023 · Low Superheat Low Subcooling: Learn To Fix It. Low superheat and low subcooling are the indicators for your evaporator to be low on heat and have a limited refrigerator in its condenser. We will recommend you maintain a suitable climate around your Living area in order to feel comfortable. Tom Moore May 19, 2023 — 5 minutes read. What to do if you have high superheat low subcooling, low superheat low subcooling, high superheat normal subcooling, low superheat normal subcooling, and so on (all scenarios explained). Overall, measuring and calculating superheat and subcooling is very useful in HVAC. ant type used. The difference in temperature is the subcooling value. Note: Condensing temperature is derived from using the PT chart. On new refrigerant blends with high temperature glide, this is called the bubble point (BP) temperature. See Figure 2. To measure subcooling with an 80PK-8 Pipe Clamp, allow the system to run long enough forRebuilding your credit is a challenge, but it’s possible to start the process by getting a credit card, paying it off regularly and keeping the balance low. This method requires yo...Well, now it has very low suction pressure plus suction-line icing-up; entirely different symptoms: Simple, when checking for restrictions: Refrigerant System RESTRICTIONS, either TXV or FIXED ORIFICE; low suction & head pres.; high superheat & subcooling; low amp draw; icing & poor Relative Humidity Control.

Subcooling is defined as the difference between condensing pressure/temperature and liquid temperature at the expansion valve inlet. Subcooling of the refrigerant is necessary to avoid vapour bubbles in the refrigerant ahead of the expansion valve. Vapour bubbles in the refrigerant reduce capacity in the expansion valve and thereby reduce ...High Suction - Low Superheat and No Subcooling 2.5 ton lennox condenser 3 ton drive on blower 3.5 ton evap 50 evap 45 SLT 100 condensing temp 105 LLT ... Elevated suction, low superheat, lowish head and low subcooling are typically symptoms of an overfeeding metering device. But 10 SC and 7 SH are reasonable numbers though 7 SH is probably ...Subcooling is defined as the difference between condensing pressure/temperature and liquid temperature at the expansion valve inlet. Subcooling of the refrigerant is necessary to avoid vapour bubbles in the refrigerant ahead of the expansion valve. Vapour bubbles in the refrigerant reduce capacity in the expansion valve and thereby reduce ...Actual Box Temp. Cond Temp should be ±10∘F Actual Cond Temp = Cond Subcooling = (2) Actual Evap Temp = (1) Evap Temp should be TEV 80∘. Question: (7) Symptoms Service Problem 7-4 Cond. Temp: High Low Normal - Walk-in FREEZER Subcooling : High Low Normal - R404A Evap. Temp : High Low Normal - TEV Superheat : High Low Normal (9) Repair ...Limitations of the Superheat Test First, superheat won't be accurate unless air˜ow is around 400 cfm per ton, so air˜ow should be mea-sured and improved, if inadequate. Sometimes you can't charge by superheat because of either low or high outdoor temperature. Superheat disappears at high outdoor temperatures, and charge-check-In this HVAC Video, I Explain Superheat and Subcooling in the Refrigeration Cycle to Understand the Operation Easier! I go over how to understand the importa...

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Airflow. Low suction pressure, txv is trying to maintain superheat, subcooling means liquid should be hitting the valve. I would get it 10-12 SC just to make sure but I doubt it would help in this case. 20 degree split also says it's not refrigerant related. Check static pressure and blower wheel. If static is high, it's duct work.1 post · Joined 2023. #4 · Mar 5, 2023. High superheat with a normal subcooling occurs in a refrigeration or air conditioning system when the refrigerant vapor leaving the evaporator is heated to a temperature above its saturation temperature at the given pressure. The causes of high superheat can include:Here's Where Lowe's (LOW) Stands After Earnings Are Released...LOW Shares of home improvement retailer Lowe's Companies (LOW) are slumping in early trading after the compan...A: Low on refrigerant charge. B: Low on evaporator airflow. C: Refrigerant overcharge. D: There is probably nothing wrong with the system. B: Low on evaporator airflow. The normal compression ratio for a typical comfort air conditioning application should be in the range of. A: 1 to 2. B: 1.5 to 2.25.Also, the TXV's job is to maintain 8 to 15 degrees superheated, so having low superheat and high subcoooling could be an overcharge. Check the amperage on the compressor and see where it's at. ... 4 degrees of superheat with 22 degrees of subcool almost looks like an overcharge, but your pressures aren't adding up right. ...

The result is low superheat. Here is how we fix low superheat due to overcharged AC unit: We have to remove the refrigerant (R-22, R-410A, R-134A, etc.). This is simple to say but hard to do. We have to leak the AC unit, and that job is best left to licensed HVAC technicians (with a license to drain freon). This is not a DIY low superheat fix.If superheat is low and sub-cooling is high: Charge must be adjusted. System overcharged If superheat is high and sub-cooling is high: Could have blockage in coil, orifice or line set. If superheat is low and sub-cooling is low: Orifice could be too big, there is no orifice in the unit of the orifice is stuck and refrigerant is by-passing it.In my thread asking how high charge level causes high subcooling, you told me that low charge level causes low superheat because the refrigerant gets subcooled less in the condenser which makes the refrigerant enter the evaporator at a warmer temperature, which leads to more superheat. ... High superheat with low condenser sub-cooling generally ...System Information R22 2.5 ton: Low Side: 115. High Side: 240. Return Air: 83. Suction Line Temp: 75. Measured Super heat: 5. Super heat should be around 15. Low superheat is an indication that liquid refrigerant not changing state in the evaporator and is possibly flooding back to the compressor.High subcooling on one circuit and low subcooling on the other circuit Resolution: RTAA, RTWA, RTUA, DX Evaporator: Between the evaporator head and evaporator tubesheet a gasket is present. If this gasket were to get a tear or nick in it, it could allow a circuit to circuit leak to develop.The higher the outdoor ambient air temperature, the lower the superheat, with fixed metering. Head pressure goes up with outdoor ambient, and concurrently so does mass flow through the evaporator. Assuming same return air wet bulb, elevated head pressure combined with elevated mass flow allows for less superheating of the …possible to see the superheat set-ting as low as 5 °F to 10 °F. A low or zero superheat read-ing indicates that the refrigerant did not pick up enough heat in the evaporator to completely boil into a vapor. Liquid refrigerant drawn into the compressor typi-cally causes slugging, which can damage the compressor valves and/or internal mechanical Superheat and Subcooling are technical readings in an HVAC that measure the Freon (refrigerant) reading. Superheat measures the Freon boiling point in gas form while subcooling measures the Freon in liquid form below the evaporation level. To calculate superheat and subcooling measurements, a specific Mathematical chart is used, and the process ...

I've got a situation where my subcool is a bit high (15 instead of the 8-12 range) but everything else is within design parameters (pressures, superheat, delta-t). ... Lower than recommended subcooling means low charge, higher than recommended means overcharge. ... This will result in low superheat (refrigerant is not saturating soon enough ...

Study with Quizlet and memorize flashcards containing terms like A walk-in with TEV has the following conditions: Subcooling is 0° Superheat is 25° Which of the following could cause this condition?, A reach-in with cap tube has the following conditions: Subcooling is 25° Superheat is 0° Which of the following could cause this condition?, A walk-in with TEV is 10° too warm and has the ...The superheat value can indicate various system problems including a clogged filter drier, undercharge, overcharge, faulty metering device, restricted airflow, or improper fan motor or blower direction. Suction line superheat is a good place to start diagnosis because a low reading suggests that liquid refrigerant may be reaching the …Compressor amperes: low. Low side pressure: 11.6 psig/10° High side pressure: 95.0 psig/85° Ambient temp: 80° Calculated Values. Condenser split: 5° Condenser subcooling: 10° Evaporator superheat: 15° Superheat at compressor (total): 45°Study with Quizlet and memorize flashcards containing terms like Low subcooling usually takes place when the system charge is too high., High superheat levels are an indication of a flooded evaporator coil circuit. Suction line pressure drops can be found with a digital temperature probe., If the suction pressure is 68 psig and the refrigerant is R-22, the evaporator temperature is 68°F. and ...Therefore the Superheat will be high when the charge is low (assumes cap tube). A low charge also lowers the head pressure (and corresponding saturation temperature). The gas takes longer to condense due to extra heat. This leaves less time for subcooling at condenser exit, hence a low subcooling reading. Sound good?I agree, charge with suction superheat on straight cool [only] and then verify the subcooling with a clean-as-new condenser coil. The subcooling changes as the coil ages too. Verify with checking Discharge superheat [apx 100 degrees]. Charging with subcooling only works to get the highest efficiency on High SEER matched system.High superheat= not enough refrigerant in the evaporator. Low subcool= not enough refrigerant in the condenser Compression ratio is fine, unlikely to be the valves. It isn’t possible for you to have liquid refrigerant in the liquid line if the line is hotter than the boiling point of the refrigerant. A Negative subcool number is not a thing.

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Fig. 6 compares the heat duty of the two tube surfaces under evaporation dominated conditions (high superheat/low subcooling). It can be seen from the figure that the total heat duty from the porous tubes is greater than that of the plain tubes for the entire solution flow regime. As mentioned earlier, the figure also shows that the sensible ...High subcool and low superheat readings; Cookie Consent ... Here's the operating conditions at the time I looked at it: outdoor DB 84deg, indoor DB 68deg, indoor WB 56deg, low side 111psia, high side 339psia, SC 16.3deg, SH 5.9deg, compressor volts 243v @ 16.4amps, indoor airflow ~1230cfm, R410a, TXV. This is a power draw of 3.98kW and the ...20°F. Notice the 30°F of liquid subcooling backed up in the condenser in this overcharged system. Because of this overcharge, the condenser will have too much liquid backed up in its bottom, causing high condenser subcooling. With an overcharge, increased liquid subcooling amounts will be realized in the condenser.Yes, high superheat and low subcooling can harm your HVAC system. High superheat levels can cause the air conditioning system to deliver less cooling. It can also cause the compressor to overheat, potentially damaging it. The same goes for low subcooling.1. Low Refrigerant Charge (Most Common Cause) The most common cause for high superheat is low refrigerant charge. Namely, if our AC unit doesn’t have enough freon, you will see that the metering device will underfeed the evaporator coil. Now, there is not enough refrigerant in the evaporator coil.High discharge pressure, high suction pressure. with high super heat and subcooling; Cookie Consent We use cookies to improve your website experience. ... I have 325psi on the high side and 87psi on the low side. The superheat is 31 degrees and the sub cooling is 40 degrees. It does not have a txv. Reply . 07-27-2011, 09:01 PM #6. hvacjamie.Study with Quizlet and memorize flashcards containing terms like Refrigerant in the evaporator: a. Changes from a vapor to liquid b. Changes from a liquid to a vapor c. Stays in the vapor state d. Stays in the liquid state, What does a high evaporator superheat indicate?, A low evaporator superheat indicates: a. Undercharge b. System restriction c. Overcharge d. High superheat and high subcool is usually a indicates an restriction in the refrigeration line. I'm new here, just wanted to grab some knowledge. I'm working with a newer Lennox R410A (13SEER) unit. The call was for not cooling properly. Any help would be great! Your subcooling is 19° and your superheat is 16°. Superheat gives us a look at how well we are matching refrigerant flow to heat load. High superheat means evaporator underfeeding; low superheat means overfeeding. There is an issue, though. We could have a correct superheat and still have a coil temperature of under 32°—this is unacceptable in an air conditioning system.Jess Gordon is the service manager at Tempo Mechanical Services, Irving, TX. The company was Contracting Business magazine’s 2003 Residential Contractor of the Year. Jess can be reached at 972-579-2000, or by e-mail at [email protected]. Superheat is a way to ensure that the system is boiling off all of the liquid before it exits the evaporator.Normal superheat low subcool . So here’s the stats, I have a normal superheat, and low subcool, my coil temp is 42f 130psig on suction side, with suction line temp of 51f And on my high side I have a head pressure 220psig, 74f on the condenser coil temp and the liquid line read at 71f. My delta was around 12 with a 72f return air and 60 ...On traditional HVACR systems, which utilize mechanical metering devices such as a TXV or cap tube, the superheat heating will vary between 8°F to 20°F. On newer systems, which use electronic expansion valves and solid state controllers, it is possible to see the superheat setting as low as 5°F to 10°F. ….

Low capacity, a starved evaporator, high superheat, and low suction pressure are all symptoms of a(n) _____. ... high subcooling and high compression ratios are all symptoms of a(n) _____. refrigerant overcharge. All reciprocating compressors should immediately go into a vacuum if the suction line is valved off when the compressor is running ...Low pressure due to low refrigerant charge will be accompanied by a warm suction line and a high superheat (see "Checking Superheat"). If the suction pressure is low and superheat is low (cold suction line) DO NOT ADD REFRIGERANT. If the suction pressure is low and the superheat is high try adding refrigerant. If the pressure does not come up ...Low subcooling means you won't have enough liquid refrigerant to feed your expansion valve. High subcooling means you may have to much refrigerant in the system or you have a subcooling circuit in the system that helps subcool the liquid refrigerant more. I've seen subcooling circuits on chillers and VRF/VRV systems.In this podcast episode, we ONCE AGAIN talk about superheat and subcooling. This episode is a recap to help people who struggle with the concept. You get superheat when you have 100% vapor, and you have subcooling when you have 100% liquid; any liquid-vapor mixtures are in a saturated state. We usually measure superheat outside at the suction ...Superheat determines by how many degrees of temperature refrigerant vapor increases in the system. We are usually looking for 7°F to 15°F superheat.Too low superheat (below 2°F) = Risk of flooding the compressor, too high superheat (above 15°F) = Risk of overheating the compressor.More about that in our general superheat and subcooling article here.Anything above the boiling point is all vapor, and it's superheated. Very high superheat indicates that the refrigerant boiled off very early in the evaporator, meaning that the system could be low on charge. On fixed-orifice systems, you charge a system via superheat. Zero superheat indicates that you have liquid in the suction line.Aug 12, 2019 · The difference of the two temperatures is the subcooling value. Trouble diagnosis Data from superheat and subcooling measurements can be useful for determining various conditions within the HVAC/R system, including the amount of refrigerant charge and verifying the operating condition of the metering device. These measurements can also be used ... The most important values for checking to superheat and subcool are the endpoints of the glide or the pressure-temperature relationship for saturated liquid and saturated vapor. ... the operating pressure for the low side of a system can be found by cross-referencing the desired coil temperature on the PT chart. For high-glide blends, however ...Subcooling is when the liquid refrigerant in your is colder than the minimum temperature required to keep it from boiling. This can happen when the system is first turned on, or if there's a problem with the system. When this happens, the liquid refrigerant can change from a liquid to a gas phase, which can cause problems with the HVAC system.MEASURING SUBCOOLING As with superheat, knowing a system's subcooling will reveal its refrigerant state. In addition, it will be of use in diagnostic procedures and verifying proper refrigerant levels. Measure high-side pressure before the evaporator. Convert this pressure to its equivalent saturation temperature using a pressure-temperature ... Low subcool high superheat, Troubleshooting Using Superheat and Subcooling Data. Low superheat: Indicates too much refrigerant in the evaporator, likely due to overcharging. High superheat: Suggests too little refrigerant in the evaporator, which may be caused by low refrigerant levels, insufficient heat reaching the evaporator, or a dirty/defective metering …, Step 3. Subtract the evaporator saturation temperature from the thermocouple temperature. This difference is the system superheat. This shows the temperature rise above the bubble point temperature of the system. Review the operating specifications for your system to determine the proper superheat. Inadequate superheat can cause liquid ..., It's simply shedding heat energy, moving left all the way through the saturation dome, and even subcooling the refrigerant slightly at the end. Point 3: The "throttle" is the metering device that separates the high-pressure condenser from the low-pressure evaporator — usually a thin capillary tube in household refrigerators., Jul 22, 2022 · To measure liquid subcooling: 1. Attach your gauge manifold to the liquid line service port. If you use a quick-connect fitting on the end of your hose, make sure it’s a low-loss fitting. I’ve seen some quick-connect fittings that allow pressure loss, which can cause inaccuracies in the charging procedure. , For superheat measurement, we use the blue low side gauge. The red one (high side) is for measuring subcooling on the liquid line. Needless to say, we: Don’t want a very low superheat (0°F, 1°, or 2°F) since this indicates liquid refrigerant might be entering the compressor. The compressor can only handle vapor, not liquid., In my thread asking how high charge level causes high subcooling, you told me that low charge level causes low superheat because the refrigerant gets subcooled less in the condenser which makes the refrigerant enter the evaporator at a warmer temperature, which leads to more superheat. ... High superheat with low condenser sub-cooling generally ..., The fix. How to Check For Superheat. What is subcooling and what does low subcooling mean? Chart for low subcooling causes and possible fixes. 1) Defective …, If superheat is low and sub-cooling is high: Charge must be adjusted. System overcharged If superheat is high and sub-cooling is high: Could have blockage in coil, orifice or line set. If superheat is low and sub-cooling is low: Orifice could be too big, there is no orifice in the unit of the orifice is stuck and refrigerant is by-passing it., subcooling somewhere around 12-15 degrees F. Suction Pressure around 21-22 psia = -15 to -14 deg.f. Suction line temp. leaving evap. = -12 to -2 deg. F. (The temperature swing is -12 to -2) It stays quite stable. Isn't radical with the temp. swing. box temp. -5. It's an empty walk in box about 7 x 10 foot square., What causes High Superheat and Low Subcooling Liquid Line Restriction. The refrigerant passes through a liquid line in the HVAC system. The normal flow of the liquid means that you will be able to maintain optimum levels of the refrigerant. However, if there is a restriction or a blockage that restricts the flow, problems will be inevitable., How to Calculate Superheat. 1. Obtain suction line temperature: First, measure the temperature of the suction line near the evaporator outlet using a digital thermometer or a clamp-on thermocouple. 2. Determine saturation temperature: Next, read the low side pressure gauge on your HVAC gauges while equipped with corresponding refrigerant scale ..., Mar 15, 2024 · What causes Low superheat with high subcool. When both low superheat and high subcooling occur simultaneously, it signals a unique condition that can only be attributed to an overall excess of refrigerant in the system. Overcharging the air conditioning system with refrigerant is the primary cause of experiencing both low superheat and high ... , Replace air filters and the blower wheel. Overfeeding of the metering device. Ensure sensing valve of the TXV is properly insulated. Insufficient heat load to the coil. Clean the filters and the coil. Oversized AC system. Consider going for a well Sized AC unit. Read also: How to Fix High Superheat Low Subcooling., One of the leading theories about depression is that it’s caused by low levels of serotonin. But the connection has not been proven. There’s a long-debated theory that low serotoni..., Liquid line temp 101 degrees and the suction was 49 degrees. The low subcooling and low suction pressure indicate low airflow. The somewhat low deltaT seems to contradict that. Could be a significant amount of air bypassing the coil based on your report, which would account for all of the numbers that you posted., Superheat and subcooling data can help you pinpoint these issues quickly. Common Causes of Superheat and Subcooling Imbalance. Common reasons for superheating and subcooling include issues such as liquid line restriction, malfunctioning metering systems, and limited airflow, all of which can lead to high superheating and low subcooling levels. 1., Study with Quizlet and memorize flashcards containing terms like High Superheat, Low Superheat, High SubCooling and more. ... High SubCooling. Flooded Condenser. Low SubCooling. Starved Condenser. Superheat. Tells you what's going on in the evaporator. SubCooling., low Suction press / low suct line temp indicates low air flow through evap. coil. But, 245# head on 78 degree day seems a little high, especially with only 60# suct. Of course 78 'f' outside is going to make yur condenser very efficient, so the increased subcooling could be attributable to the OAT., 3. Airflow through the evaporator is too high. When there is an excess flow of air through the evaporator coil, the capability of the system to remove moisture is reduced. The vapor picks up more than usual heat which causes the suction pressure to be higher than normal pressure and has a higher superheat. 4., In this video, see how to use the superheat and subcooling troubleshooting procedure to evaluate a refrigeration or air conditioning system. To learn about t..., A high superheat is an indication of either a low refrigerant charge or a liquid line restriction problem. To tell the difference between the two problems, we look at subcooling. A system with a low refrigerant charge will have a low subcooling. A system with a liquid line restriction will have a normal to high subcooling., Low subcooling means you won't have enough liquid refrigerant to feed your expansion valve. High subcooling means you may have to much refrigerant in the system or you have a subcooling circuit in the system that helps subcool the liquid refrigerant more. I've seen subcooling circuits on chillers and VRF/VRV systems., The symptoms are low suction, normal subcooling, and high superheat when a TXV fails "shut," but there are some other issues to watch for that can actually result in overfeeding the coil. Schrader in the Port. The external equalizer tube on a TXV connects to the suction line at the evaporator outlet and provides a closing force to the valve., To make the adoption of low-code technology hassle-free, this platform comparison guide covers a lot of basic as well as more advanced information to evaluate the top low-code plat..., Here is a table with these causes that will help us understand why we get low superheat normal subcooling: Low Superheat Causes: Non-Normal Subcooling Causes (High Or Low): Indoor airflow (CFMs) is too low. Oversized AC unit. Outdoor airflow is too low (or condenser coils heat exchange is impeded). High refrigerant charge (overcharged AC unit)., 20°F. Notice the 30°F of liquid subcooling backed up in the condenser in this overcharged system. Because of this overcharge, the condenser will have too much liquid backed up in its bottom, causing high condenser subcooling. With an overcharge, increased liquid subcooling amounts will be realized in the condenser., Aug 29, 2016 · In this HVAC Video, I Explain Superheat and Subcooling in the Refrigeration Cycle to Understand the Operation Easier! I go over how to understand the importa... , High superheat can be caused by (the culprits that at the same time cause low or high subcooling are crossed out): Low refrigerant charge. Restriction in the liquid line. Too …, Take readings on the superheat, subcooling, evaporator coil and condensers, and compare their temperature or pressure with the optimal operating conditions specified by the manufacturer. 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 ..., Figure 1 is an example of a superheat-charging curve instead of a table. The curve is based on 400-cfm/ton airflow at 50% relative humidity across the evaporator coil. The steps to charge a system according to this curve are listed below. 1. Measure indoor drybulb temperature (DBT)., For this example the Liquid line Temp is 95 degrees. Subtract the Liquid line Temperature from the Liquid Saturation Temperature and you get a Subcooling of 15. "Typically" on TXV systems the Superheat will range between 8 to 28 degrees with a target of about 10 to 15 degrees. The Subcool range on TXV systems will range from about 8 to 20., High subcooling is usually accompanied by high head pressure because liquid is displacing available condensing area. Low superheat, low evaporator load - dirty filter, slipping belt, low fan speed, filthy coil. High superheat, evaporators being starved for refrigerant if suction pressure is low. If suction pressure is high and superheat seems ..., I come back the next day expecting to have to pull charge out and the subcool being way high. The unit cooled the house down to 70 it's probably 85 outside. These are my readings 296psi high side, 95.8 lstat, 93.6 line temp, 2.3 subcool. 140.6psi low side, 50.1 vstat, 51.3 line temp, 1.2 superheat. 20degree delta tee across the return and supply.