DEFROST MODE

Auto ac repair in miami Free estimates and check ups by ase certified tech

Defrost Mode.Damage to compressor due to low refrigerant charge.

On many vehicles, by selecting the defrost position on the controls, it will also activate the A/C compressor. Cooling the air with A/C first will remove more moisture from the air so it can do a better job clearing the windows.If the A/C system is not functioning correctly this ability will be lost. If your A/C system is not working 100%,with low refrigerant charge over the winter months, you’re not getting the refrigerant oil back to the compressor which is damaging it all winter season that will lead to costly repairs in the spring time. If you run into any issues regarding this system have a professional mechanic from Auto A/C Repair. help you diagnose and fix it.
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Auto A/C Sight Glass diagnosis.

A/C SIGHT GLASS DIAGNOSIS.

A sight glass is a transparent glass tube or window installed in a tank or boiler system that allows an observer to view what is happening inside the system.

The refrigerant sight glass is normally located anywhere liquid flow exists and anywhere it can serve a purpose. When it is installed just prior to the expansion device, the technician can be assured that a solid column of liquid is reaching the device. When it is installed at the condensing unit, it can help with troubleshooting.

Sight glasses come in two basic styles: plain and with a moisture indicator. The plain sight glass is used to observe the refrigerant as it moves along the line. The sight glass with a moisture indicator can tell what the moisture content is in the system. It has a small element in it that changes color when moisture is present.

What you see in the sight glass can help you diagnose system malfunctions. It is strongly suggested that you do not use the sight glass as the only means of diagnosis. Also, do not use the sight glass to diagnose R134a systems.

If the sight glass is clear, one of three conditions can exist: the system is completely empty, the system is full, or the system is overcharged. If there is foam, the charge is low, but if there are only a couple of bubbles, it is probably Ok. few bubbles when the compressor cycles on is normal. Oil streaks in the sight glass usually indicate a low charge and that the compressor is pumping oil from its sump. If the sight glass is cloudy, the desiccant bag has probably burst.

If an R134a system has a sight glass, do not use it or try to perform diagnosis, as it is normal to observe bubbles in this type of system.

 READING A SIGHT GLASS

SIGHT GLASS CLEAR

System Ok

System overcharged

System empties (No refrigerant)

SIGHT GLASS, FOAM, BUBBLES OR MIST.

System low on refrigerant

System contaminated with air

SIGHT GLASS STREAKED

System may be low on refrigerant

Oil may streak as oil circulates

CLOUDED

Desiccant breakdown 

Contaminated system

Can I drive my car with a bad AC compressor?

Will a bad AC compressor affect the engine?

A bad compressor could affect the engine in your car. If your compressor’s pulley bearing goes bad, your engine can stall due to the stuck compressor or the serpentine belt may break affecting all the accessories moved by the serpentine belt.

Clutchless variable displacement piston compressors and compressor lock up. 

Clutchless variable displacement compressors have extra protection in case the compressor seizes.In the event  a compressor failure occurs the bridges on the clutch assembly will break and only the pulley will keep running, allowing the engine to keep running.

Does engine coolant affect ac performance?

High coolant temperature affects A/C performance.

The engine cooling system has an indirect influence on the performance of the A/C system. High under hood temperatures can be the cause of poor A/C output. 

Always verify correct operation of:

  • Engine coolant level and condition
  • Low coolant will cause high under hood temperatures
  • Does the cooling system need flushing?
  • Has the vehicle followed the manufacturer’s service intervals for flushing?
  • Does it have the correct coolant in it?

  • Thermostat
  • Has the thermostat ever been replaced?
  • Is it stuck, not closing or opening all the way?

  • Radiator
  • Is the radiator plugged internally or externally?
  • Are there any signs of leaks?

  • Water pump
  • Is the mechanical pump circulating the coolant properly?
  • Are electric pumps working properly?
  • Should it be replaced when servicing the timing belt?
  • Belts,tensioners,and pulleys
  • Check for proper belt tension and verify the belt is not slipping
  • Check tensioner alignment

Why did my car AC stop blowing air ?

My car A/C stop blowing air from the vents.

Common reasons for this to happen:

  • A/C blower motor circuit blown fuse
  • Bad blower motor resistor
  • Blower motor shorted
  • Bad blower motor control switch
  • Poor ground connection
  • Poor blower motor connections

Ram air flowing through the evaporator does not provide enough air flow inside the vehicle for cooling purposes. So, a blower is used to force the air along. An electric motor spins a fan, forcing the air into ducts, which direct it to the particular vent selected by the operator.

If the blower motor gets full voltage, it will run at high speed, but that is not always desirable. Therefore resistors are used to cut the speed down. The fan switch directs the current flow through one or more resistors to achieve the slow and medium speeds.

Why did my car AC suddenly stop working?

The most common causes of broken air conditioning are:

Leaks, compressor issues, electrical / electronic faults.

Compressor and electrical / electronic faults.

Inputs that may affect A/C clutch operation include (but are not limited to):

  1. A/C system pressure
  2. Engine speed
  3. Throttle position
  4. Engine coolant temperature
  5. Intake air temperature
  6. Power steering pressure

If these sensor and switch values are either above or below the programmed operating range, the compressor clutch may not engage

Depending on the vehicle, additional items that may affect compressor operation could include:

  1. A/C mode switch/actuator
  2. Body control module
  3. High and low pressure cut-out switches
  4. Compressor clutch cycling switch
  5. Refrigerant pressure transducer

Refrigerant leaks .

There are two types of refrigerant leaks in the automotive air conditioning system: Active leaks and Passive leaks.

  1. The active refrigerant leak is a continuous leak. It doesn’t matter if the engine or ac system in your car is off or on hot or cold the refrigerant continuously leaks out
  2. The passive refrigerant leak is a type of leak the intermittently occurs. They are really hard to find, because technicians should recreate the same conditions of pressure, temperature or vibration for the leak to happen.

When should I change my AC filter drier?

Receiver-drier location.

The receiver drier is a storage tank for the liquid refrigerant from the condenser. It also contains a bag of desiccant.

The purpose of the desiccant is to absorb any moisture that might enter the system during assembly or service. The receiver drier is often neglected when the air conditioning system is serviced or repaired.Failure to replace it can lead to poor system performance or replacement part failure.

When should I change my AC filter drier?

It is recommended that the receiver drier and /or its desiccant be changed whenever a component is replaced, the system has lost the refrigerant charge, or the system has been open to the atmosphere for any length of time.

AC receiver drier refrigerant flow restriction.

If the receiver-drier outlet is colder than the inlet, this unit is restricted and should be changed to restore efficient and proper system operation.

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.

What does the AC receiver drier do?

Should I replace my a/c dryer when I replace my compressor?

The filter drier is a device that removes foreign matter from the refrigerant. This foreign matter can be dirt, filings, moisture, parts, and acid caused by moisture.

Some sources of moisture in the refrigeration systems include poor service practices, air trapped from improper evacuation techniques, leaky systems, and improper handling of lubricants.

Filter drying operations are accomplished with a variety of materials that are packed inside the drier. Some manufacturers use chemical beads and some use porous blocks made from a drying agent.

The most common agents found in filter driers are:

Activated alumina.

Molecular sieve.

Silica gel.

Silica Gel: It’s a no crystalline material with molecules formed by bundles of polymerized silica, forms a weaker bond with water, which is why silica gels are not widely used in modern filter driers.

Molecular sieve dessicants: Are sodium alumina-silicates in cubic crystalline form. The crystal structure is a honeycombed with cavities that are uniform in size that can selectively absorb molecules based on their charge (polarity) and size. These properties allow water to be absorbed while still permitting the larger molecules like refrigerants and their lubricants to pass by. The surface of the desiccant is coated with cations, which are positively charged and act like magnets to attract polarized molecules such as water. Molecular sieves retain the highest amount of water and keep the concentration of water in the refrigerant low. The molecular sieve filter is recommended for use as liquid line filter driers because of these good water-removal capabilities. The strong bond between water and molecular sieve thus keep the occurrence of system corrosion, acid formation, and freeze ups very low.

Inorganic acids like hydrochloric and hydrofluoric acids are formed when high system temperatures break down refrigerants and water. These acids can attack metal surfaces in the system and destroy the crystalline structure of the molecular sieve.

In the presence of the wrong desiccant and water, organic acids can then form from the broken down refrigerant lubricants. Organic acids, sludge like material, can plug up metering devices.

Activated Alumina: It’s formed from aluminum oxide. It is not a highly crystalline structure like a molecular sieve; its pores vary in size and do not absorb molecules based on pore size. Because of this ,it can absorb much larger molecules like refrigerants and lubricants along with water. Activated Alumina is even more effective in removing  organic acids when it is used in the suction line of the refrigeration system. This is why some manufacturers recommend using a suction-line filter drier made of activated alumina for acid cleanups.

Filtration,another main function of a filter drier,can also be done with a screen.A screen will filter or catch particles that cannot fit through its wire mesh.As particles and contaminants start to cover the mesh of the screen,they act as a fine filter that removes even smaller particles.

Filters may also include the following:

Bonded desiccant cores

Fiberglass pads

Rigid fiberglass with a resin coating. 

Does the ECM control the air conditioner?

Engine coolant temperature sensor (ECT) and,ECM air conditioner compressor control.

If the coolant temperature rises to a predetermined level, the ECM will disengage the compressor clutch. This helps an overheating engine by allowing the condenser to cool down and by removing the mechanical load of driving the compressor.