6 Tips on AC System Maintenance for Diesel Trucks

Since 1969, the number of vehicles with air conditioning units has grown from 50% to over 99%.

AC systems for trucks are a must-have in the hot summer months. It’s necessary to keep your AC system running properly by checking it regularly.

Continue reading to learn about AC system maintenance.

How the AC System Operates

To identify and understand possible issues with your AC system, you have to know how AC in a truck works.

You may not be qualified to fix the problem yourself. On the other hand, some AC issues have simpler, doable solutions. It’s useful information to have even if you decide to leave it to the professionals.

Here are the steps to how AC functions.

Step 1

Gaseous refrigerant, which takes the humidity out of the air, enters the compressor. The compressor is a pump attached to the engine by a belt. It can only compress gasses.

As the engine runs, the belt works to move the compressor. This leads the pressurized refrigerant into the condenser. 

Step 2

The condenser is a series of tubes that removes heat. There is air moving throughout the tubes.

The heated refrigerant travels through the condenser. By the end, it becomes a liquid. 

Think of moisture in the air forming condensation. 

Step 3

Next, the refrigerant enters the receiver-drier.

This component of the AC system absorbs water with desiccants. You’ll find these little particles in silica gel packets.

Water left in the system can turn into ice and damage your AC unit.

Step 4

The thermal expansion valve or TXV changes the pressure of the refrigerant.

As the name suggests, the TXV lets the refrigerant expand. In turn, this lowers the pressure of the liquid.

The valve controls the amount of refrigerant going through using pressure detection. 

If your truck doesn’t have a TXV, it has an orifice tube. 

Orifice tubes don’t control how much liquid passes in. Instead, the whole system turns off and on to regulate the amount.

Step 5

Finally, the refrigerant is in the evaporator. Located in the vehicle cab, an evaporator looks like a condenser. 

Its job is to collect heat and turn the liquid refrigerant into a gas. It also removes humidity.

The heat from the cab boils the refrigerant. The blower in front of the evaporator moves cool air into the car. 

The gaseous refrigerant travels back to the compressor and the cycle continues. 

AC systems with orifice tubes have an accumulator after the evaporator. The accumulator catches any refrigerant that doesn’t boil.

AC System Maintenance

Knowledge of how AC systems work can help you better maintain them. Regular AC maintenance is important to prevent damage that can lead to bigger issues.

Here are some tips for maintaining and fixing AC systems.

Recharge the System

AC systems should be recharged every 2 years. A recharge involves replenishing the car’s refrigerant and lubricant.

Lubricant keeps the parts of the AC moving smoothly. Condenser lubricant or oil also acts as a sealant and a heat remover

There are different kinds of lubricant and refrigerant. Only use the appropriate type for your AC system.

Air Filter Maintenance

Clean the air filter in your truck every 6 months. Replace the filter every year.

Locate the filter either beneath the dash or behind the glove box compartment. Remove the debris. You may also run it under water.

Wait for the filter to dry before putting it back.

If you don’t keep up air filter maintenance, dirt and other debris will affect the evaporator. The cool air blowing into the car won’t be clean.

Unclog Debris

Debris can get caught in the small grills near the windshield and in the front grille. This can clog the condenser. The condenser is often between the radiator and the front grill. 

Take a hose to power wash the grills. Open the hood and wash the condenser. You can also request this at a car wash.

Routine Runs

Let the AC system work about 10 minutes once a week. Put on the coldest and highest settings. This goes for the colder months as well. 

Running the system will keep the proper gas pressure. The compressor will continue to run correctly.

Does the cool air blowing out smell? This could be from a dirty air filter or the build-up of moisture. 

Even if the filter is clean, turn on the defrost function for 5 to 10 minutes once a week. 

Defrosting the truck removes unwanted moisture and stops mildew build-up. 

No Cool Air?

There are various reasons for a system to not deliver cool air. Some include a broken fan and low refrigerant levels.

You can check for low refrigerant levels to make sure that is the issue.

Put the AC on the highest setting and listen for a loud click. This means the compressor has started working. 

The system is low on refrigerant if it continues to click. You can also feel the bottom of the condenser. Warmth is an indicator that there is sufficient refrigerant.  

When you get a recharge, ask your service provider to add tracer dye. This will find possible leaks.

Regular Service

The entire AC system in your truck should be serviced every 4 or 5 years. 

Besides recharging the system, professionals check every part for leaks and other problems.

A note: it’s normal for water to accumulate and drip from an evaporator. You’ll likely see it dripping from under the from of your truck. 

Humidity in the air turns into water and builds on the evaporator.

Perform Regular AC Maintenance

Keep the inside of your truck comfortable during hot weather and perform basic AC system maintenance. 

Something as easy as turning on the AC and cleaning the air filter will save you money. Prevent AC system damage and follow these tips.

Of course, the time comes when you have to turn to professionals. 

Check out this full list of maintenance services.

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