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How much refrigerant does a car need?

What happens when refrigerant is low?

A low refrigerant charge may cause faster than normal clutch cycling without frosting of any components.

 AC system overcharged.

A flooded evaporator would cause elevated low-side pressures and frost to develop on the suction line.

AC system restriction.

A restricted accumulator would likely result in a noticeable temperature drop.

Why does car stall when AC is on?

Why does my car hesitate when AC is on?

A vehicle that is stopped stalls when the steering wheel is turned to full lock only when the air conditioning is on.

The power steering pressure switch signals the computer to increase the engine idle speed during parking-type maneuvers. If the vehicle has a bad power steering pressure switch, the engine could stall at idle when the steering is moved to the full lock position. This is due to increased load on the engine from the power steering pump.

A/C cycling clutch systems.

In cycling clutch systems with a fixed orifice tube, a low-pressure or cycling clutch switch is placed in series with the compressor clutch circuit so it can turn the clutch on or off.

Air conditioning system protection devices.

The AC cycling switch de-energizes the clutch and stops the compressor if the pressure gets below a certain level (usually about 20-25 psi) .It closes and turns on the compressor at about 40-47 psi.

Dirty evaporator core.

Air flow restriction.

When the fins and air passages of an evaporator are clogged with dirt, air will have a difficult time passing through the evaporator. Since the principles of air conditioning require the heated air around the evaporator to lose heat, a vehicle with a clogged evaporator will have poor A/C performance.

Evaporator core maintenance.

The evaporator core should be removed from the case to properly clean it. Airborne debris, such as leaves, lint, hair, and other contaminants, enters the evaporator case and clings to the wet evaporator core.

The A/C drainage.

The drain is for the purpose of removing the condensation that forms as a result of humidity being removed from the intake air. It is nearly impossible to adequately clean an evaporator core without first removing it from the case.

The blend door constantly moves back and forth.

A faulty feedback device can cause the blend air door to hunt for the desired position.

Blend door actuator diagrams.

The feedback device is typically a potentiometer that uses three wires. One wire is the input voltage from the controller; a second wire is the return ground from the controller; the third wire is the signal wire to the controller.

A/C compressor bracket damage.

There is a noticeable noise coming from the engine compartment when the A/C is selected.

A compressor noise is often difficult to locate. When the compressor is operating, a loose compressor mount or bracket may vibrate, giving the impression that the compressor itself is somehow defective. This type of noise usually stops when the compressor is disengaged.


A/C compressor off.

If the system did not have any refrigerant in it, then the low pressure devices would prevent the A/C compressor from running.

A/C Refrigerant flow restrictions.

The air passages through an A/C condenser are severely restricted.

This may result in high refrigerant system pressures and refrigerant discharge from the high-pressure relief valve.

A/C system performance.

These restrictions will not allow enough air to cool down the condenser, causing higher temperatures and result in higher pressures.

What causes ac freon leaks ?

Moisture in an A/C system.

If moisture enters the A/C system, it mixes with the refrigerant to form harmful acids. These acids damage the ac components from inside out.

How to prevent acids from forming.

The method of removing any moisture from the A/C system is to pull a deep vacuum on the system. Pulling a deep vacuum on the system, will cause any moisture to vaporize and be pulled out of the system.