Is AC suction line supposed to be cold?

The Copper Pipe (Suction Line) should be sweating and cold to the touch during a hot day. If it is not cold, your compressor could be off (bad capacitor/ hard start kit) or low on Refrigerant.

Why is my AC liquid line cold?





The main reason why your AC lines are freezing is because your evaporator coils are getting too cold. The evaporator coil is filled with refrigerant which cools the air in your HVAC system. When things are working properly the evaporator absorbs the heat from your air and provides a cooling effect.

Should the suction line be hot?

And the suction line will be warm. Again, it is easy to understand why the liquid line is cold, but difficult to understand why the suction line is warm. The warmest a suction line can be is whatever the return air temperature that is blowing across the evaporator is.

What temperature should the liquid line be?

Also, note how much warmer the liquid line is than the outdoor temperature. It should be between 3°F and 20°F warmer than the outdoor temperature. If it is above or below that range, connect gauges.

How do I know if my liquid line filter drier is clogged?

If the filter drier is partially clogged, there may be a few degree temp drop across it. However, if the filter drier is completely clogged, there will be a large temperature drop across it and likely frost due to the low temp of the refrigerant exiting the clogged filter drier.

Why is my high side AC line cold?





Sounds like the filter dryer is plugged
its a restriction. check your brazed LL connections for “solder balls” inside the joint. then the high side line gets cold all the way to the filter dryer. after the filter dryer it gets luke warm .

Why is my suction line warm?

The suction line separates hot liquids from other fluids before turning the liquid refrigerant to a gas and transferring it to the compressor. If the suction line backs up, it may feel exceptionally hot to the touch.

How cold should AC return line be?

Well, the general consensus is somewhere between 14 to 20 degrees colder than the intake temperature. From my example, 55 to 61 degrees would be an acceptable range.

What should suction line temp be 410A?

Suction Pressure / EVAP DTD Rule of Thumb
However, this rule of thumb (obviously) does not work on an R-410A system. A more applicable guideline is 20˚-25˚ suction saturation below outdoor ambient. This means if it is 50˚ outside the suction saturation temperature should be between 25˚and 30˚ (on most systems).

How often should a liquid line drier be replaced?



every 2 years

All filter driers should be replaced every 2 years or by manufacturer’s recommendation. The Receiver Drier’s function in an automotive a/c system is to filter foreign material, remove moisture from refrigerant and to act as a reservoir to supply liquid refrigerant to the TX valve.

What are the symptoms of a bad Txv?

Bad TXV valve symptoms

  • There is frost on the evaporator.
  • Your unit is blowing warm air.
  • The AC compressor is running constantly.


What happens if a liquid line drier is installed backwards?

When installing a new filter drier, an arrow on the filter drier’s housing will indicate which direction refrigerant is designed to flow. If installed backwards, the filter drier will become useless.

What happens when a refrigeration system is overcharged?

The higher head pressures of an overcharged system will have a tendency to overfeed the evaporator, thus decreasing the superheat. If the system is overcharged more than 10 percent, liquid can enter the suction line and get to the suction valves or crankcase. This will cause compressor damage and eventually failure.

How are liquid line restrictions diagnosed?

Symptoms of a liquid line restriction include:

  1. Low evaporator (suction) pressure;
  2. High superheats;
  3. Higher-than-normal discharge temperatures;
  4. Low amp draw;
  5. Short-cycle on low-pressure control (LPC);
  6. Somewhat high discharge temperature;
  7. Low condensing (head) pressure;
  8. Low condenser split;

How can a technician determine when a filter drier is stopped up and needs changing?



How can a technician determine when a filter drier is stopped up and needs changing? The pressure drop will exceed 2 psig. In most commercial refrigeration systems, most of the excess refrigerant that is not being used is stored in: The liquid receiver.

What are the most common causes of a restricted liquid line?

Liquid line restrictions can be caused by a restricted filter-drier, a restricted thermostatic expansion valve screen, a kinked liquid line, a bent lower condenser coil, or an oil-logged capillary tube. An evaporator that is starved of refrigerant will house a starved compressor and condenser as well.

Can you unclog an expansion valve?

Place the bulb into hot water. This should cause the expansion valve to open allowing more refrigerant to pass through the TXV into the coil. Suction pressure should rise, and super heat should drop. Opening of the valve should be relatively quick.