Why Isnt My Semi Blowing Cold Air?

How Air Conditioning Works

The term "making it colder" is somewhat misleading. After all, air conditioning units in commercial vehicles do not take cold air and blast it but rather transfer vapor refrigerant through a timely process to make air blow from warm to cool. If your wondering why your semi-truck is not blowing cold air, it could be several reasons.

Now that spring has arrived, and warm weather is here to stay, it is no wonder why truck drivers want to kick-start their A/C units and make routine maintenance, as necessary. Today, we will explore the components of an air conditioning unit; how air conditioning works; most common failures of A/C and how to fix the parts.

How Your Truck's A/C Works

Your truck's A/C working partially depends on the engagement and disengagement of the compressor clutch – which turns the compressor with help from a drive-belt.

The process starts with your truck's a/c compressor. This pump takes low pressure vapor and expels it under higher pressure to a [metal fin] condenser (located in front of the engine's radiator) which then, takes the vapor refrigerant and condenses it to liquid. Next is the help from an expansion valve – a tiny hose – that allows air to pass through to passenger compartments at a reduced size. The size of the line reduces the pressure of the liquid passed on from the condenser and forces evaporation.

At this point, you may be thinking that evaporation will lead to warmer vapor, but hear us out. With help from the blower motor and evaporator, the evaporation process begins. After the blower motor routes the air flow to the evaporator, low pressure vapor absorbs the heat and disburses it from the inside into the atmosphere through the grill essentially ending the cycle – like it started. The cycle will repeat itself when the high-pressure liquid moves back through the expansion valve. Depending on the A/C unit, a receiver drier and accumulator may also be used to store liquid refrigerant and help trigger air movement.

Most Common A/C Failures

These A/C components, as well as other electrical parts such as sensors, must talk to each other to perform its function and minimize the risk of damage and pollution to the entire A/C system. Refrigerant leaks from hoses, O-rings, compressors, and evaporators is the most common type of AC failure. System contamination from blocked refrigerant can occur from weakened expansion valves, butthe worst-case scenario is that the compressor is so polluted that it leads to a replacement of all A/C component parts.

How To Fix A/C In Heavy-Duty Trucks?

Check for leaks by conducting a dye-test in your HVAC system. You should check system sensors and see if you have any broken switches, as well. If your high-pressure switch is malfunctioning, it could lead to disturbances in air flow. Engine mold and other contamination may be a bigger issue that can lead to full system repair, as mentioned above. Check for leaks and damage to components, too.

Performing routine maintenance check-ups on your truck will help to avoid costly repairs down the road and leave you with cool air as you move throughout spring into the heat of summer.