What does it mean when the low side is high and the high side is low?

Asked By: Antxon Calles | Last Updated: 21st March, 2020
Category: home and garden indoor environmental quality
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Lower Low Side and Higher High Side Pressures
This condition usually means there is a restriction in the system or the TXV/Orifice Tube is blocked or closed.

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Just so, what should the high and low side pressures be?

The low-side should be near 30 PSI at 90 degrees Fahrenheit or less. Pressure that is too much lower or higher shows there is a problem. On a properly working system, high-side pressure will be about twice the ambient temperature, plus 50 PSI.

Furthermore, which is low pressure side AC? The low side line of the system will have a larger diameter metal pipe than the high-side. The low side service port is usually located between the AC compressor and evaporator. The low side service port will have a black or blue plastic cap that needs to be removed.

Also question is, which side is the high side on air conditioning?

The high side, or discharge line, will be the line connected to the compressor from the bottom or lower position. It will not be wrapped in insulation and will be warm to the touch. This is where freon exits the compressor as a liquid.

What should the gauges read on 134a?

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 225 psi and 250 psi.

39 Related Question Answers Found

What should the low side pressure be in a r134a system?

This chart details how ambient temperature correlates with the system refrigerant charge pressure, and how it affects high and low side psi readings.

R134a Pressure Gauge Chart.
Ambient Temperature (°F) Low Side High Side
70° 35-40 psi 140-165 psi
65° 25-35 psi 135-155 psi

What should the high and low side pressures be for 410a?

Manifold sets should be at 750 psi (high side) and 200 psi (low side), with a 500-psi low-side retard. Use hoses with a 750-psi service pressure rating. Leak detectors should be of the HFC type. R-410A is compatible with POE oils.

Why is my high side pressure low?

Lower Low and High Side Pressures
Lower than normal pressures on both high and low side, with the correct amount of refrigerant, could mean a problem building pressure in the system or too much heat is being removed at the condenser. A pressure switch or sensor could be bad.

What should the low side pressure be in a r22 system?

Low side pressure for ac is going to vary slightly depending on metering device, expansion valve, capillary ect and load/return air temperature. At minimum you want to see above 58 psi which corresponds to 32 degrees f (freezing point of water ) to avoid freeze ups.

What should the low side pressure be on a refrigerator?

Although the low side pressure should be around 2 psig, at times it can fluctuate from 0 to -3 psig. If the low side pressure rises to over 10 psig, the system has too much refrigerant. When the refrigerator's compressor first begins running, the pressure will appear higher than normal.

What is the low side of a refrigeration system?

The low side of a refrigeration system usually houses the evaporator, suction line, and any accessory components located within the suction line. Accessory components can include evaporator pressure regulator valves, suction filters and driers, crankcase pressure regulator valves, and suction accumulators.

Do you fill AC on the high or low side?

The LOW side fitting is usually located on the suction hose or line that goes from the accumulator to the compressor. The HIGH side fitting is located on the line that goes from the compressor to the condenser.

Do you add refrigerant to the high or low side?

The freon is added on the LOW PRESSURE SIDE ONLY. The hose tool you bought is made so you can only hook to the low side as the high side and low side fittings are different sizes and shapes for SAFETY'S SAKE.

Is high side red or blue?


The low side usually has a blue cap, and the high side has red.

What are the symptoms of bad valves in a compressor?

3 Signs of Bad Air Conditioner Compressor Valves
  • Poor Efficiency. Efficiency decreases are the most notable effect of bad compressor valves.
  • Excessive Discharge Temperatures.
  • High Suction Pressure.

Which line is bigger liquid or suction?

The larger line typically carries a cool gas and is insulated. This is commonly referred to as the suction line, but it is also called the return line or vapor line. The smaller uninsulated line typically carries a warm liquid. It is most often called the liquid line.

Which line is the suction line on an auto AC?

The suction hose is the cold line. Since it carries refrigerant to the compressor from the evaporator, it is lower in temperature than any line in the A/C system except those inside the evaporator itself.

Which is the suction port on AC compressor?

The compressor has 2 ports, an inlet and outlet, or 'suction' and 'discharge' respectively. The suction port is always the larger diameter hole. Refrigerant is 'sucked' into the compressor, compressed, and 'discharged' through the outlet, headed for the condenser.

What is the high pressure port for?


The high side service port is a fitting that provides access to the high pressure side of the AC system and the low side service port is a fitting that provides access to the low pressure side of the AC system.

Should AC return line be hot?

What temperature should the refrigerant lines be? When the system is operating, the large insulated suction line should be cold to the touch and sweating at any point where there is no insulation. The smaller uninsulated liquid line should be warm to the touch after the system has been operating for 10 or 15 minutes.

Which line is low pressure on home AC?

The low pressure hose is normally blue and is connected to the suction line which is the larger of the two pipes. The high pressure hose is typically red and is connected to the liquid line which is the smaller of the two pipes.