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134a pt chart automotive

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134a pt chart automotive

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Basic Air Conditioning ~ Pressure Temperature Chart 101

Tom Greenleaf. RA has a slightly lower pressure at evaporator temperatures degreesbut Ra also has a much higher pressure at condenser temperatures degrees. NOTE: For best heat transfer, condenser temperatures should be degrees hotter than the ambient air temperature entering the condenser. Tags: None. Brought this over from the old site as it's by "ACProf" and valuable information as a tool in the form of a chart. Comment Post Cancel. Thanks, I refer to it often.

Thanks Tom. That's a nice chart to have posted. Readers: That chart do note how many cars are and have been around without a high pressure port. So when or if a problem comes along you want to know the pressure and without a port can quick use a touchless infrared thermos on lines and know the pressure! This info can be obtained if the vehicle's now computer monitored pressures can show on a scanner most folks are unlikely to buy to be able to get streaming info of what's going on.

Places that matters include many not just a few will shut off electric fans if not needed or increase their speed for the condenser. If static pressure in a system not working is below the listed pressure with known temps you about know that system is almost empty and not be wasting time and money move on and find the leak which would be pretty fast if it was recently working.As an air-conditioning refrigerant in newer automobiles, the optimal running pressure for RA is between 22 and 57 pounds per square inch.

Ass a refrigerant, a liquid capable of vaporizing at low temperature, used in automotive air conditioning, the U. Environmental Protection Agency, states that RA is not flammable at ambient temperatures and not corrosive to metals such as aluminum, copper and stainless steel.

Like other refrigerants, the pressure of RA corresponds to its temperature. In a high-temperature refrigeration box, where temperatures typically range from 45 to 60 degrees Fahrenheit, the coil temperature is, typically, between 10 and 20 degrees Fahrenheit colder than the box itself.

This difference is simply known as the temperature difference. In other words, the normal running pressure of RA is between 22 and 57 psi in such a system. A full-time writer sinceDavid Dunning is a professional freelancer specializing in creative non-fiction. About the Author. Copyright Leaf Group Ltd.For more information about conducting tests using temperature probes, see this post.

Many sources tell you to start your charge diagnosis by checking static pressure. Measure static pressure with the engine off and AC not run for at least one hour. That allows the high and low pressures to equalize. But static pressure readings can only tell whether the system is completely empty or has some refrigerant in it. It can never tell you whether the charge is correct! Well, Ra boils at The ONLY thing a static pressure reading can tell you is if there is enough pressure in the system to satisfy the low pressure switch and allow the compressor clutch to engage.

If your static pressure shows more than that, the compressor clutch should engage. If the high and low gauges read 0, the system is empty.


The ONLY way to know if your system is properly charged is to evacuate it and add new refrigerant with a scale. The same applies if your system is overcharged. Measure temperature about 1-ft in front of the grille. This is really important. Click on the image to find which type of system is used on your vehicle.

Normal Running Pressures for R134A

To find out what in your vehicle, click on the image to the right and find your vehicle. For example, you might see a low high side pressure and determine the compressor is bad, when in fact, your vehicle is equipped with a variable displacement compressor.

Click on the image above and find the type of refrigerant metering device your vehicle uses. What is this so important? Because expansion valve systems usually show show a lower suction side pressure than an orifice tube system. See the pressure chart below to see what I mean. Unscrew the protective port caps and store in a safe place. Connect the quick release connectors to the service ports on the high and low side refrigerant hoses.A vehicle's air conditioning system is an important component in hot weather.

The A refrigerant, and its resulting manifold pressure, provide a way to maintain the coolest air for the vehicle's occupants. Run through a car's air conditioning system, A refrigerant acts as the cooling conductor for the air. Periodically, the refrigerant can become low, resulting in warmer air through the system and into the vehicle. While recharging the system with refrigerant, the A manifold gauge pressure should be monitored so the proper amount of refrigerant is used.

Two different pressure gauges can be used, either low or high. For a low pressure gauge, a reading of 25 pounds per square inch psi to 40 psi is optimum. On the other hand, a high pressure gauge should read between psi and psi.

If the refrigerant becomes low after a few months of circulation, there may be a leak in the system. AA1 Car recommends having the leak repaired before trying to recharge the system again.

This article was written by the It Still Works team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information.

To submit your questions or ideas, or to simply learn more about It Still Works, contact us. Considerations If the refrigerant becomes low after a few months of circulation, there may be a leak in the system.

About the Author This article was written by the It Still Works team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information.If your staff do not understand the gauges they do not understand air conditioning. This is a basic introduction to gauge reading which is relevant to most vehicles but not all and as such it should only be used as a guide.

The vehicle should be recovered, vacuumed and charged prior to testing. When reading your gauges there are a couple of basic facts that should be considered —. Ambient temperature Compressor type. The system should be recovered, vacuumed min 20 minutes and charged.

The gauges readings will depend on the ambient temperature. The table below shows the comparison between temperature and pressure for Ra. Pressure and temperature will change together, as one goes up the other goes up, as one goes down the other goes down. Different refrigerants will have different figures. As the ambient temperature rises the red gauge rises 40psi up to psi and the blue gauge remains at a constant low 20psi to 35psi.

The red gauge stops increasing as the fan cuts in, typically between psi and psi. The compressor is either on full or off the familiar clicking sound as the compressor engages.

This is controlled by a temperature sensor, when the system is cold enough the compressor turns off, as the temperature increases the compressor turns on. The gauge readings will be as above when the pump turns on and off. Initially the compressor is on full, when it reaches the required temperature, it will reduce the amount of refrigerant being pumped through the system there is no clutch plate to click on or off, it is internally regulated.

This is controlled via sensors through the ECU. When less refrigerant is being pumped the pressure on the red gauge will be lower. In cool weather, once the required temperature is reached, the red gauge will barely increase, this may give the impression that the compressor is not pumping, even though it is.

Examples of faults. If both gauges do not move, the compressor is not pumping. Possible faults include — fuse, pressure sensor, fan belt slipping, relay, wiring break, no gas, compressor fault. If the compressor is pumping against a blockage the red gauge will be too high. If there is a blockage on the suction side of the compressor blue gauge the pressure will fall.

If the red gauge is over psi check if the fan is working. Possible fan switch fault, this may be a single switch near the condenser or combined with the pressure switch if it has 4 wires. Poor cooling in the vehicle. If the red gauge is too low and the blue gauge is too high.

R-134a Ambient Temperature and System Pressure Relationship Chart

Possible fault — the compressor has lost its tolerances therefore it cannot build up enough pressure on the discharge side red gauge and cannot create enough suction on the inlet side blue gauge. So recover, vacuum and charge everytime.Images of normal operating pressures for r22 hvac system ra pressure chart temperature pressure chart for r 22 a c a and a refrigerants pt charts r22 rc ra ra jpg x hvac pressure sensitivity r22 pressure temperature chart.

Hvac training pressure guages and the temperature chart charging air conditioners with the superheat method air conditioner repair typical compressor superheat charging chart how to find target and actual superheat charging chart how to find target and actual r22 operating pressures pressure with regard to pt chart aranui co.

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134a pt chart automotive

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You also have the option to opt-out of these cookies. But opting out of some of these cookies may have an effect on your browsing experience.Ra is the most common refrigerant found in automobiles today. That being said, there are still millions of cars on the road that use Ra and there will be continue to be for at least another decade or more.

One of the very first steps is to check the pressure of your system. Understanding the pressure that your system is at as well as knowing what the saturation point is of Ra will allow you to properly diagnose what is wrong with your system.

Remember, that air conditioning is basically changing the pressure on the refrigerant until a state change is reached. If your pressure is off then that could point you in the right direction. With the facts behind you can then begin to determine if your compressor is at fault, perhaps your condenser, or it could be something as simple as your blower motor needing replaced.

Without knowing the pressure in your system and the corresponding saturation point then you are in essence going in blind when you attempt to troubleshoot your air conditioning system.

I can assure you that when you take your vehicle into a dealership that the pressure and temperature are one of the first things they check when troubleshooting.

There you have it folks. I hope this article was helpful and if you find that something is inaccurate here in my chart please do not hesitate to reach out to me. I have sourced this the best I could but there is always going to be conflicting data. The aim with this article is to give you accurate information so again, if you see anything incorrect please let me know by contacting me here.

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