Why don't my AC lines get cold?

Author: Prof. Orrin Hodkiewicz DVM  |  Last update: Saturday, August 30, 2025

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 line not getting cold?

If your AC is running but not cooling, it could be due to a dirty air filter, incorrect thermostat settings, a malfunctioning thermostat, a refrigerant leak, dirty condenser coils, blocked vents or ducts, a faulty compressor, frozen evaporator coils, or electrical issues.

Should AC lines feel cold?

The larger or low side line should be cold and usually sweating, the high side, or smaller line should be hot to the touch if the compressor is doing its job.

Why is my AC suction line not cooling?

Problems with Suction Lines

If AC suction lines are clogged, improperly sized, bent, or kinked, the flow of vapor will be affected. If the line is compromised, the compressor will not receive an adequate amount of refrigerant, which can affect the entire system.

What happens if AC lines are not insulated?

Winter erosion, UV damage and condensation may require insulation replacement to avoid temperature fluctuations or malfunctioning. With worn insulation or no insulation at all, refrigerant lines may absorb heat, reducing the system's cooling capacity.

How to Fix Car AC that's Not Blowing Cold Air

Should both AC lines be insulated?

Most air conditioning systems have a low-pressure and a high-pressure refrigerant line. Of these two lines, you typically only need to insulate the former. Insulating the high-pressure refrigerant will protect against condensation.

How do I know if my AC line is bad?

AC is Producing Warm Air

One of the surefire signs of a clogged refrigerant line is if you notice the AC producing warm air when you expect cold air. The warm air is caused by a problem with the proper circulation of the refrigerant fluid, which is instrumental in cooling the air.

Why is my AC running but not getting cooler?

There are a number of reasons why your air conditioner might be running but not cooling. It could be an issue with the thermostat, the compressor, or the evaporator coils. Or, it could simply be clogged with dust and debris, which is preventing it from working properly.

What happens if the suction line is not insulated?

While smaller the high pressure liquid line does not need to be insulated, the larger low pressure suction line requires insulation to protect it from condensation. Without insulation around this line, thermal energy is lost and condensation forms, which can both lower efficiency and cause moisture damage to the unit.

What are the symptoms of a restricted suction line?

Restriction Consequences

The system will have symptoms of low suction pressures, high evaporator and compressor superheats, normal-to-high condenser subcooling, low compressor amp draws, and low head pressures.

What are the symptoms of a bad expansion valve?

You can tell your AC expansion valve needs attention if you notice one of the following problems.
  • Blowing Warm Air. ...
  • Constant Running. ...
  • Making Whistling Noises. ...
  • Inconsistent Air Temperatures. ...
  • Frozen Coils.

How do I know if my AC lines are clogged?

A clogged AC drain line symptoms include:
  1. Musty, moldy smell near your indoor unit or in air from the registers/vents.
  2. Standing water near the indoor unit.
  3. Water damage in areas near the indoor unit.
  4. AC system is not cooling your home.
  5. AC system shuts down or doesn't turn on.

Are AC lines supposed to freeze?

As air passes over the evaporator coil, the refrigerant extracts heat, keeping your home nice and cool. When an evaporator coil becomes dirty or breaks, it cannot sufficiently draw in heat. As a result, it becomes too cold, leading to frozen AC lines. To fix the problem, you'll need to replace the evaporator coil.

Should the suction line be cold?

Overall, you'll want your temperature to be below 65 degrees at the compressor inlet. If you see a lower temperature, then you'll want to start looking at airflow.

How to check if AC is cooling properly?

Ways To Check If Your AC Is Working Properly
  1. Check the Air Flow. If your AC is trying to cool a room that continues to stay excessively warm, it may not getting enough airflow through the vents. ...
  2. Check the Thermostat. ...
  3. Check for Refrigerant Leaks. ...
  4. Check the Smart Settings. ...
  5. Check the Outdoor Unit.

Why is my car AC full of freon but not cooling?

The compressor plays a vital role in the A/C system, as it pressurizes and circulates the refrigerant. A compressor that is not functioning correctly can cause warm air to blow from the vents. Common issues that can affect the compressor include a faulty clutch, electrical problems, or mechanical failure.

Why is my AC suction pipe not 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. Your Breaker is Tripped. Be Careful because this usually indicates a problem with the compressor or wiring.

Which AC lines need to be insulated?

Insulation on the suction line is a vital component of the air conditioning unit. The suction line must be well insulated to protect against condensation and keep the line cold. Otherwise, the cooling process becomes interrupted. The line labeled as “FREON IS GAS” is the suction line.

Does the length of a pipe affect AC cooling?

From the experiment, it is obvious that the cooling capacity of the air conditioner decreases as the refrigerant pipe length increases. For the pipe length of 5.5 m to 15 m, the cooling capacity decreases from 2352 W to 2281 W.

Why is my AC not blowing as cold as it should?

First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.

Why is my compressor running but not cooling?

If you're wondering, “Why is my AC compressor working but not cooling?” The problem may lie in several potential factors, including refrigerant issues, compressor malfunctions, or airflow blockages.

How to unclog an AC drain line?

How to Unclog Your AC Drain Lines in 9 Steps
  1. Turn Off Your Air Conditioner. ...
  2. Locate the Drain Line Pipe. ...
  3. Remove the Cap From the Pipe. ...
  4. Inspect the Drain Line Pipe. ...
  5. Unclog the Drain Line Pipe. ...
  6. Pour in Vinegar. ...
  7. Use a Wet/Dry Vacuum Cleaner. ...
  8. Reconnect the Cap to the Drain Line Pipe.

What are the symptoms of a clogged AC condenser?

4 Common Warning Signs that You Have a Bad AC Condenser
  • Your Air Conditioner is Not Cooling Your Home. ...
  • Your Air Conditioner is Making Strange Noises. ...
  • Your Air Conditioner is Not Turning On. ...
  • Your Air Conditioner is Leaking Refrigerant.

How do I know if my AC line is low pressure?

The A/C compressor can also be identified because it has two metal tubes coming out of it. The two tubes are different sizes. The smaller tube is the high-pressure line. The larger-diameter tube is the low-pressure line, which is the one you're looking for.

Are AC lines supposed to get hot?

When you touch the copper (some will be exposed between the insulation and the unit), it should feel cold. It should also have condensation on the outside. If the line set is cold and sweating, your AC is cooling. If not, your AC isn't working properly.

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