Tag: AC poor performance

The AC compressor should last for the entire life of the car,usually 8-10 years.

System maintenance and compressor efficiency

The compressor’s efficiency can be improved by maintaining the correct working conditions. This involves keeping the suction pressure as high as practical and the head pressure as low as practical within the design parameters.
A dirty evaporator will cause the suction pressure to drop. When the suction pressure goes below normal, the vapor that compressor is pumping become less dense and gets thin (sometimes called rarified vapor).The compressor performance declines. Low suction pressures also cause the high-pressure gases caught in the clearance volume of the compressor to expand more during the piston’s downstroke.This gives the compressor a lower volumetric efficiency. These gases have to expand to a pressure just below the suction pressure before the suction valve will open. Because more of the downward stroke is used for reexpansion, less of the stroke can be used for suction. Suction ends when the piston reaches bottom dead center. Low evaporator pressures cause high compression ratios.
Dirty condensers also cause compression ratios to rise, but they do not rise as fast as with dirty evaporator.A dirty condenser makes the head pressure to rise. This causes the amount of refrigerant in the clearance volume (at the top of the compressor cylinder) to be greater than the design conditions allow and the compressor efficiency to drop.
If there is a dirty condenser (high head pressure) and a dirty evaporator (low suction pressure), the compressor will run longer to keep the refrigerated space at the design temperature. The overall efficiency drops.
Evaporator core and condenser core maintenance will increase the life of the air conditioning compressor,improve the A/C efficiency and cooling capacity.With regular A/C maintenance we are saving money in the long run and getting the most out of the air conditioning system.

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

What are the symptoms of a bad fan clutch?

Slipping fan clutch.

A slipping fan clutch would not affect ram airflow. This problem will reduce airflow at low speeds causing reduced air conditioning performance at low speeds.

Proper condenser airflow.

Reduced airflow across the condenser would elevate both the high and low side pressures. Airflow across the condenser is created by vehicle movement. A fan clutch allows the fan to freewheel when ram airflow is greater than the fan induced airflow. A slipping clutch would not change ram airflow.

A locked up fan clutch.

It is also common for a fan clutch to lock-up which will cause problems for the water pump, the belt drive, and the engine’s horsepower output. A locked up fan clutch will not reduce A/C cooling efficiency. Reduced airflow across the condenser generally affects the ability of the condenser to cool the refrigerant, resulting in higher temperatures and pressures in both sides of the A/C system.

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.

air conditioning service near me

The air-conditioning system cools satisfactorily during the early morning or late evening, but does not cool during the hot part of the day.

The problem is that the A/C system seems to work fine in the early morning and evenings, but does not during the heat of the day. During a performance test, the low-side gauge reads normal and then drops dramatically.

  • Ice could be forming on the expansion valve
  • The receiver drier could be saturated with moisture

Moisture in the system can be released from the desiccant in the receiver-drier by an increase in temperature on the high side. When the ambient temperature is lower the desiccant may be able to hold the moisture out of the refrigerant. Internal freezing of the expansion valve could produce external icing on the valve.