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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Normal auto A/C vent temperature

Higher than normal auto a/c vent temperature.

Heater control valve malfunction

When the A/C is in operation, the duct outlet temperature is higher than normal on a vehicle equipped with a normally closed vacuum heater control valve.

Heater control valve stuck-open.

A stuck-open heater control valve would allow the heater core to add heat to the cooled air reducing the effectiveness of the a/c system.

With a normally closed heater control valve, vacuum would be applied to the valve to cause it to open and add heated air.

Vacuum would not be applied to the valve in A/C mode so a vacuum leak would not cause this problem.

Heater control valve stuck-closed.

A stuck-closed valve would restrict coolant flow to the heater core and the complaint would be no heat.

How to find an A/C evaporator core leak?

The inside of the windshield has an oily film, and the A/C cooling is inadequate.

An oil film on the windshield could be cause by a refrigerant leak in the evaporator core that may allow some refrigerant oil to escape into the evaporator case. A/C blower motor operation in the defrost mode could carry the oil through the ducts to the windshield. 

A plugged heater case drain would not cause an oily film on the windshield. An oily film could only be caused by a refrigerant leak or by a heater core leak. A plugged case drain could cause water to leak out onto the carpet or possible a musty smell coming from the vents.

A/C system restriction.

Symptoms of a restricted orifice tube.

A restricted orifice tube would cause a lower than normal low-side pressure.

A restricted orifice tube may cause frosting of the tube.

The restriction will cause a greater than normal pressure drop that can lead to the refrigerant vaporizing at that point .Vaporization of the refrigerant will produce cold enough temperatures to cause frosting.

What does it mean when there’s ice on your AC condenser ?

Frost is forming on one of the condenser tubes near the bottom of the condenser.

This problem is caused by a restricted refrigerant passage in the condenser. When frost is forming on one of the condenser tubes near the bottom of the condenser, the refrigerant passage is restricted at that location in the condenser.

Frosting is a clear indication that there is a restriction in the condenser.

Airflow restriction. he condenser.

Restricted airflow passages in the condenser would not cause frosting; it would limit the efficiency of the system because the refrigerant would not be cooled by the air flowing through the condenser.

A/C leak.

A leak would not cause frosting either; oil may be seen at the point of leakage.

Heater core gurgling noise

Noisy A/C System . 

A gurgling noise is heard inside the passenger compartment. The noise is coming from the A/C heater case.

A gurgling noise in the heater core may be caused by a low coolant level in the cooling system or a restricted a heater core .

Low coolant level 

A low coolant level will allow too much air in the cooling system.

The excessive air in the system will mix with the coolant and create the gurgling noise.

Heater core restricted.

A restricted heater core will also cause a gurgling noise from the coolant passing through the restricted area.

A/C condenser clogged out.

What does AC condenser do?

Since the condenser is a heat exchanger that causes the refrigerant to condense back to liquid, it will not be very effective when the fins get restricted with road debris. This causes system efficiency (cooling) to drop off.

What will a dirty condenser do?

Should the high-side pressure become high enough, a relief valve will vent refrigerant to control the pressure or a high-pressure cutout switch will cut power to the compressor preventing the high-side pressure from getting too high.

A/C compressor oil.

How to add oil to the AC compressor ?

Modern compressors no longer have a dipstick to allow the compressor oil to be checked

All modern compressors require the oil to be drained from the compressor and measured in a graduated container.

If the system had a leak, the measured amount of oil may be lower than specifications. Always refer to the guidelines given by the manufacturer before adding oil.

Belt troubleshooting

Why do belts slip?

A car is equipped with an A/C compressor driven by a V-type belt. As the compressor cycles, the belt squeals briefly. A check with a belt tension gauge indicates the belt is correctly adjusted.

Belt slippage

A V belt that is not wide enough will run on the bottom of the pulley providing very little belt friction regardless of the correct tension. V belts get their friction by wedging themselves into the V groove.

What belt squeals when I start my car up?

An overcharged AC system condition can cause the high-side pressure to be so high as to resist the start-up of the compressor.

In the long run, the clutch or belt will usually fail.

Thermostat stuck open


Thermostat:Problems,symptoms.

Fiat interior dashboard

A stuck-open engine cooling system thermostat could cause all of the symptoms.

  1. Poor heater operation
  2. Below-normal engine operating temperature
  3. Increased fuel consumption: A stuck-open thermostat would cause increased fuel consumption because the engine would take longer to build engine temperature and could not sustain normal operating temperature; especially in colder climates.

Can a car overheat if the thermostat is stuck open?

Engine overheating: A stuck-open thermostat would not cause overheating. An open thermostat would be the normal position for a warmed-up engine. The engine thermostat speeds engine warm-up by restricting coolant flow until a predetermined temperature is reached. Poor heater operation and excess fuel consumption would be caused by slow warm-up. The thermostat also serves to regulate coolant flow, which keeps the engine at an acceptable and efficient operating temperature.

What is the purpose of the cabin air filter?

Cabin air filters remove dust and pollen from the outside air entering the AC system.

Cabin air filters remove dust and pollen from the outside air entering the AC system.Re-circulated air should already be cleaned by the cabin air filter as it entered the car.

All sources and heated air only are ruled out by the filter being in the outside source, which supplies air for ventilation, heating, and AC operation.