Troubleshooting Liquid Line And Suction Line Same Temperature

Last updated: April 09, 2023.

Is it normal for the liquid line and the suction line to have the same temperature?

A liquid line and a suction line should not have the same temperature. A suction line has a cooler temperature than the liquid line.Same temperature on both lines could mean some problems within the refrigeration cycle.

The temperature of the liquid line is slightly warmer than the medium where the condenser is ejecting the heat into( this might be air or water).

In this guide, you should expect to learn about about

The differences between the suction and the liquid line
What can make the liquid line and the suction line to have the same temperature and how to fix the problem

suction line vs liquid line

Suction line	Liquid line
Usually larger	Smaller in size
Typically Insulated	Uninsulated line
Often called vapor line	Often called liquid line
Carries a cool gas	Carried warm liquid
Located between the evaporator and the compressor	Located between the condenser and the TXV

What can cause the liquid line to become colder than the outdoor temperature

Restriction between the condenser coil where it becomes fully liquid and wherever you are measuring. So even if you measure a temperature difference between a liquid line dryer.

What causes the liquid line to become hotter?

If the temperature on the liquid line is higher than the temperature of the outdoor air by 15 or more degrees that’s an indication of an overcharged or a blocked condenser coil. Other things that cause the liquid line to become hot is a condenser Fan that is defector or not moving, dirty coil etc.

Reasons why Liquid Line And Suction Line Have Same Temperature

There are a few things that can cause this problem. Both lines can become cooler, close to the same temperature or bother hotter with the same temperature. Whatever the cause that indicates a problem that needs to be fixed immediately to avoid damage to your system.

1) A blocked filter drier

Under normal working conditions , a liquid line is supposed to be slightly higher than ambient temperature. But when this line gets as cold as the suction line, that’s because the filter drier is blocked by pollutants. If the refrigerant can’t move freely it can cause a drop in the temperature.

2) Low Superheat

Some internal issues can cause both the liquid line and the suction to have a similar warmer/hot temperature. But what causes a hot suction line? Low superheat due to malfunctioning of a thermostatic expansion valve.

Low superheat is a condition where there is excess refrigerant in the evaporator coil.

Another problem that can cause this issue is a failed thermal bulb that is unable to pick up the temperature signals. A TXV that is stuck in the open position could be allowing too much refrigerant in the evaporator.

3)Issue with the orifice tube

Here is how the orifice tube works;

Orifice tube works as an expansion valve to regulate the refrigerant amount flowing to the evaporator coil.

However, when its opening becomes bigger , excess refrigerant sneaks into the evaporator and creates pressure discrepancies. That can affect the temperature of the suction line causing to become nearly as warm as the liquid line temperature.

Final Thought

Now that you have learnt that when the liquid line and suction line have the same temperature that is an indication that there is a problem. With that in mind, if you can’t troubleshoot and fix the problem yourself, it’s always best to call professionals for help.

Thanks for reading.