Tag: AC condenser restriction

Condenser fan assembly

What is the purpose of the radiator fan assembly ?

The purpose of the fan is to maintain adequate airflow through the radiator and condenser core, especially at low vehicle speeds and when the engine is idling, sitting still. The fan is used to speed up the natural draft through the radiator/condenser or create one if the vehicle isnt moving.
At high motor vehicle speeds the ram effect through the air is usually sufficient enough to cool the radiator/condenser core so the fan is not required.

Three important things may happen to the refrigerant in The Condenser and we need the radiator fan assembly working at maximum efficiency for The Subcooling process to happen properly:

  1. The hot gas from the compressor is desuperheated from the hot discharge temperature to the condensing temperature. The hot gas from the compressor may be 200 F or hotter on a hot day on an air-cooled system.Desuperheating is accomplished in the beginning of the coil.
  2. The refrigerant is condensed from a vapor to a liquid. This is latent heat transfer. This is done in the middle of the coil, the only place that the coil temperature will correspond to the head pressure.
  3. The liquid refrigerant temperature may then be lowered below the condensing temperature, or SUBCOOLED.The refrigerant can usually be subcooled to between 10 F and 20F below the condensing temperature.

Condensers have a relationship to the temperature of the air passing over them. For instance, the refrigerant inside the coil will normally condense at a 30F higher temperature than the air passing over it.

The four major components that make up the air conditioning system are:

  1. The evaporator
  2. The compressor
  3. The condenser
  4. The refrigerant metering device.

The evaporator absorbs heat into the system. When the refrigerant is boiled at a lower temperature than that of the substance to be cooled, it absorbs heat from the substance.
The compressor: is the heart of the refrigeration system. It pumps heat through the system in the form of heat-laden refrigerant. A compressor can be considered a vapor pump.
The condenser: rejects both sensible (measurable) and latent (hidden) heat from the a/c system and delivers subcooled refrigerant to the metering device. This heat can come from what the evaporator has absorbed any heat of compression or mechanical friction generated in the compression stroke, and any heat absorbed by superheating the refrigerant in the suction line before it enters the compressor.
The refrigerant Metering Device: The expansion device is one component that divides the high side of the system from the low side (The compressor is the other).It is responsible for metering the correct amount of refrigerant to the evaporator. The evaporator performs best when it is as full of liquid refrigerant as possible with none left in the suction line.


What is a car ac condenser?
The condenser is one of automobile heat exchangers and operates much like the radiator.
The condenser receives the hot gas after it leaves the compressor. The discharge gas from the compressor is a high-pressure, high-temperature, superheated vapor. The temperature of the hot gas from the compressor can be in the 200F range and will change depending on the surrounding temperatures. Condenser designs have changed over the years, but there have been 3 main types. They are:
Tube and fin condenser
Serpentine tube condenser
Parallel flow condenser

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.