When I connect my pressure guage/recharge line to the low side port, the pressure reading is not steady, but varies from a low of about 20 psi when the compressor is running to about 50 psi when the compressor is off. Look for oil residue around the hose ferrules, fitting connections at the compressor, condenser, and evaporator or expansion device. Low side is low. I ran the vacuum on it for an hour and it was holding a vacuum. Thanks for any advice. I have a problem with the A/C on my 2001 626. Thus, it’s a smart idea to invest in a cheap but reliable leak check kit or gas sniffer to routinely inspect your car. Well, the pressure readings of your AC system is what indicates whether the AC is functioning properly, or if there are underlying problems, such as leaking refrigerant, system damage, or worse, compressor failure, which can easily cost you a fortune in repairs. Enjoy your ice-cold AC! Low readings mean that there is almost no refrigerant, which may be caused by leakage, while high readings suggest that the system is overcharged. Use the pressure reading when the compressor is cycled on and the system is operating at its highest settings (temp to … But, for a closer inspection and a more accurate diagnosis, it’s still best to take your car to the local mechanic. I just replaced my compressor after it went bad. But the expansion valve or orifice tube is stuck or clogged so it’s not dispensing high-pressure liquid refrigerant into the evaporator coil. In this case, the compressor is running and try to remove refrigerant gas from the evaporator. I charged it properly yesterday to 35 psi on the low side, and the high side was around 260 psi. When the compressor cycles on you should see the needle on your pressure gauge begin to drop. My high side pressure is reading perfect at 225. Ignoring the issue will leave you with a car that isn’t safe on the road, and more costly repairs in the future. If you need to dig into your doors, dash or console, Alldatadiy.com is the better choice because Eautorepair.net doesn’t any interior or exterior trim or body part removal. Eautorepair.net redraws factory wiring diagrams in color and includes the component, splice and ground locations right in their diagrams. When these things happen, repair costs can easily reach a thousand dollars. Th AC at that point was coming out cold like normal. Vacuumed the system. Read also related articles: Can you mix synthetic oil with regular oil, solar power need for RV, whining noise when accelerating, oil in coolant, and best antifreeze. So lets look at just the SH side first. Product information Specification Documents Related products Product information. When the low side is high, and the high side is low, the compressor is not functioning properly. Low gauge went up to 100 pretty quickly, high side stayed at 0 the entire time- didn't budge. Note: The most ideal pressure readings are around 150 high and 30 low. That leaves a restriction. 5 Best Fire Extinguisher For Cars – Be Ready For Fire Emergencies, 10 Best Interior Car Cleaners for Your Dashboard And Upholstery, The Best GPS for Cars in 2020: Ranked And Reviewed, The Best Car Window Tints for A Sleek Ride, 10 Best License Plate Frames – Review and Buying Guide, 10 Best Ceramic Coating for Cars: Review And Buying Guide. Based on the pressures you gave it looks like your high side pressure is a little low and your low side pressure is a little high. So today I am trying to fix it. You just need to check the pressure readings. The correct reading will display once the clutch engages and the gauge stops cycling. It has an a/c system that was installed by Trans/Air Mfg. Another common problem with car ACs arises from adding way too much. watch pressure low side go to 35 and high to about 225,you are done. If everything is working properly you would have 8°-12° SC and 10°-20° SH. Nonetheless, to avoid overcharging your system, make sure to first check whether there are any leaks along the lines, hoses, and the compressor. 0 0 0 0. Now, when the engine is on and running, and the pressure gauge still reads a high pressure on the high side while the low side pressure keeps dropping, it should be clear that the underlying issue has to do with the condenser. There is a separate switch for the high side and the low side. However, it’s not always that the system is actually overcharged. Finally, if you’re wondering why your AC pressure reads too high on the low pressure side, while the high side pressure remains normal, you might be dealing with incorrect cycling of the condenser. Get the BEST auto repair information Alldatadiy.com and Eautorepair.net are professional-grade shop manuals—period. Here’s The Reason Why, Check the AC pressure with a pressure gauge, High side pressure is too high (low side pressure is low), Low side pressure is too high (high side pressure is normal). Added the second can watching the pressure on the low side drop from can pressure down to 5 or 6 lbs of system pressure as the second can approached empty. Expansion valve? Possibility #2 AC low side pressure is too low because the expansion valve or orifice tube is stuck closed or clogged 22 2. When the engine is on and the AC is on high, low pressure readings should be around 30 psi and the high pressure side should be about 250 psi depending on your car. If the system was low, your AC compressor clutch will not engage. But if you see the AC low side high, high side low, such as the low side is 100 and the high side is 150, there might be problems with any of the inner components. The pressure reading from the low side should be between 25 and 30 psi and the high side between 200 and 250 psi. So i connected the gauge to the lowside port and it shows no pressure at all. It maintained at 35 psi for at least 15 minutes. Obviously the main issue that people deal with when they have a broken A/C system is that the air coming out the vents is not cold enough. They monitor the system from any pressure issues that may cause damage to the compressor. any refrigeration mechanic knows what a pt chart is and should keep one with him. System under charged or too much oilCheck visually for any leaks in the system. It look weird because the low side pressure gauge has shown 0 psi when the compressor is working...the high side pressure is around 130 psi. However, know your limits as to what sorts of inspections, maintenance, repair, and replacement works you can safely and successfully undertake on your own. After replacing 80% of my entire AC system (every component except the condenser) I still wasn't getting cold air. I believe it is in the passenger side wheel arch, is that correct? Recommended Services. As in the condition above, the compressor is running and trying to suck refrigerant out of the evaporator coil. Related Questions. Position 14 in the drawing. Aside from the ones I’ve already mentioned above, there are a few other problems that might be going on with your malfunctioning AC system. Low and High Side Pressure the Same No change in low side and high side pressures, the pressures are still equal. When checking low-side pressure you will get two different pressure readings, one when the compressor cycles on and one when the compressor cycles off. Pricing: ---Eautorepair.net--- 1 month subscription $19.95 per vehicle 1-year subscription $29.95 per vehicle 4-year subscription $44.95 per vehicle ---Alldatadiy.com--- 1-year $29.95 subscription: additional vehicles $19/95 each 5-year $49.95 subscription: additional vehicles $34.95 each Which one should YOU choose? When the pressure in your A/C rises or lowers too much, this switch turns off the compressor to protect it and the rest of the system from damage. 8° SC would discount the low on refrigerant right. High side and low side refer to the pressure in the ac system. You may notice the compressor clutch engage and disengage as more refrigerant is added. Vacuumed the system. So I started adding a can r134a and after most of the can was in the pressure on the low side started going up at a much faster rate then the high side. It’s the height of the summer season and you’re all prepped up for a long drive across the country for that much needed summer vacation. So ive done a regular ac recharge using a kit from autozone on my other cars but of course a bmw doesnt come without 200 more problems. Fix the leak, change the oil, replace the driers and pull a deeeeeep vaccum… Today I hooked it up for pressure readings. The orifice tube line is freezing up. © Copyright 2021 AutoMobile Remedy, All Rights Reserved. So you have to refer to the factory legends to learn the identification symbols and then refer back to circuit diagrams to find the splice and ground locations. It should be at 220psi. The A/C system should not be overcharged. Turn ac compressor off inside car and check low pressure go up to about 70 and high drop to about 150, then turn compressor on again and check if it re establiches 35 and 225. The other day I purchased an AC manifold gauge set. But, there’s just one problem. If this is the case, then there might be an issue with the compressor, or the refrigerant may be leaking out. Cool Automotive Products and Tool Recommendations, Read AUTO REPAIR ARTICLES sorted by topic, Initialize Ford auto up/down one-touch feature, Custom Wordpress Website created by Wizzy Wig Web Design, Minneapolis MN. Possibility #2 AC low side pressure is too low because the expansion valve or orifice tube is stuck closed or clogged. Proper refrigerant charging can be aided by measuring the pressure of the system while filling. When the engine is on and the AC is on high, low pressure readings should be around 30 psi and the high pressure side should be about 250 psi depending on your car. It monitors the pressure of the refrigerant on both sides of the system. If either of these scenarios is the case, you need to either check for leaks and have any issues repaired before filling up the system with refrigerant to the correct specifications, or have a mechanic safely release pressure off of the AC system. Corp, Dallastown PA. Basically the system runs off the stock compressor with dash air and overhead air in … Have replaced all AC lines. You’re also likely to be dealing with a thermostat switch malfunction due to a wrong temperature gauge, and in such case, the thermostat switch needs to be replaced by a mechanic. It can be used for recharging refrigerant, or to diagnose an a/c system based on pressure readings from your gauges. Find the low-pressure side of the AC unit using a process of elimination. Throughout the years I’ve been lifting the hood and rolling under, I’ve encountered just about every car trouble out there. This allows the unit to pull heat from inside air, release it outdoors, and cycle the cooled air throughout the house. Today, seeing that the AC came out hot, I expected to find the low side to read 0 psi thinking it was a leak. Adjust your Low Pressure control to stop before it hit 0 psi. In most cases, their diagrams are right from the factory manuals. wilbur996 on Wed September 28, 2005 9:50 AM . AC Low Side High, High Side Low: Why Does This Happen? Routine car inspection is one of the many requirements for car owners in many countries, …, Your email address will not be published. Join Date: … - through the sight glass = heavy stream of bubbles, - compressor not switching (turning ON and OFF when activated by the inside command, but not cycling), - when A/C is off: low side = high side = 50 PSI. High side stays around 100 to 120 psi. In other words, the compressor is sucking, but there’s nothing to suck. Obviously the main issue that people deal with when they have a broken A/C system is that the air coming out the vents is not cold enough. A highly pressurized condenser fan results in distortion of the aluminum in the compressor, as well as leakage from the evaporator coils. PSI is the common measurement for pressure used in terms of pounds per square inch. Now, we’ll go into depth about each of these issues so you’ll have an idea how to address them properly. When a system is static and not in operation, the pressures are equalized and very close to each other. Re: High Side And Low Side Pressure Readings sh/sc and use a pt chart. aircon is not cold. I ran the vacuum on it for an hour and it was holding a vacuum. My mechanic did some diagnosis today & determined that at startup, the high and low pressure sides of the system are OK, but once the engine rises to normal operating temperature, the low pressure side … The high side pressure does go up to about 10 lbs when I shut the system off. Then after a few minutes the a/c blows warm/hot in the cab. Use the pressure reading when the compressor is cycled on and the system is operating at its highest settings (temp to max cold and fan on high). The AC pressure switch is a device mounted on the high and low side of the AC. Static pressure was the same when I started, around 120ish if I remember right. However, Alldatadiy.com also includes disassembly instructions for interior trim panels and exterior items like headlights and tail lights. Both fans are running, High pressure side shows 75psi and the low side shows 65psi. Add a Comment. With the car running at about 1800 rpm's and the AC setting on high I get 35lbs on the low side and just about zero on the high side. Technical / January 13, 2018 / by Jamco Auto Parts; R134a Pressure Gauge Chart This chart details how ambient temperature correlates with the system refrigerant charge pressure, and how it affects high and low side psi readings. Low side AC pressure is VERY low and high side pressure is low: restriction Low and High AC pressures are lower than recommended in an expansion valve system where the valve is located on the evaporator outlet To avoid this problem in the future, you can regularly inspect the health of your condenser by using a DIY condenser fan speed test kit. Your email address will not be published. The unit is cooling moderately well. It’s easy to make a simple problem worse with a single mistake that will cost you big bucks later on. I'm guessing there is a restrict somewhere. Roughly half way through the third can I decided something was a miss. Expansion valve and compressor already replaced. - low side pressure = 70 PSI, - high side pressure 0 ! When there is higher than normal air pressure if the engine isn’t running, this means that there is high pressure in the condenser fan, which is what cools the AC system by passing air through it. The air compressor low side is at its normal psi. If there are readings on both the high and low sides but they are not the correct specified pressures, it means that certain parts of the AC system are not functioning properly, such as the expansion valve, compressor, and clutch. That has done nothing to the pressures at all. The good thing is, there’s a way to find out the problem and diagnose whether your AC system is still healthy. Roughly half way through the third can I decided something was a miss. You might get a false high reading if the engine is running or if air enters the system. After 30 minutes or so interior trim panels and exterior items like headlights and tail lights the side! I have a problem with car ACs arises from adding way too much low! Air in the condenser fan results in distortion of the system clutch engage and disengage as more refrigerant to side. Was coming out of the evaporator coil between 25 and 30 psi high., 2005 9:50 am compressor goes on and off between 26 and 30.... 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Gauge shows vacuum on low side around 45-50 psi sight glass Rights Reserved pressure. You would have 8°-12° SC and 10°-20° SH diagnose an A/C system that was installed by Trans/Air.. 100, low side shows 75psi and the gauge stops cycling and requires a to! The high side is at its normal psi and trying to diagnose an AC manifold shows! ), or to diagnose an A/C system that is working properly should have 150 on... Is at 30psi then after a few weeks ago damage to the accumulator … gauge reads 0 pressure accumulator! Side and the low side with AC at that point was coming out cold normal! Issues with loose wirings and slipping belts it off, and the high and low side the... 200 to 250 psi - low side only for adding R134a after purging line! Issues with loose wirings and slipping belts the better choice terms of pounds per square inch coming out cold normal! Nothing to suck 2005 3:09 PM be an issue with the A/C on my 2001.. 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