Air Conditioning System Performance for Semi Trucks

Summer's heat reminds us of the critical role that air conditioning plays, especially for truck drivers. The intense heat can be exhausting, making it challenging to relax and potentially leading to fatigue—a dangerous state for anyone behind the wheel. One essential step to combat this and ensure the proper operation of your air conditioner is to properly maintain the A/C system's filters. 

Why Are Air Conditioning Filters Important? 

  • Efficiency A clean filter helps the air conditioning system run efficiently. An overburdened or clogged filter makes the system work harder.  In extreme cases, a clogged A/C filter, if left unchanged, can cause the AC system to fail and/or have permanent damage. 
  • Cleaner AirReplacing filters regularly can eliminate unpleasant odors and reduce allergens in the cab, providing a more comfortable environment for the operator and passenger.  A healthy operator is a safe operator. 
  • Prevention of Costly Repairs: Proper maintenance can avert issues that could lead to expensive repairs down the road.  A/C system failure, not only results in added maintenance cost, but also reduced income due to lost road time when your truck is in the shop. 



Maintenance Recommendations:  

Fresh-Air Filter:  This should be part of your daily check.  Depending on your make/model, the fresh air filter is typically located under the hood and against the firewall. 

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To check this filter, open the hood, remove the cover, and conduct a visual inspection of the filter.  A flashlight may be needed. 

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If the filter is dirty, remove any large debris and replace it with OEM spec filter.  According to the manufacturer’s recommendations and depending on your make/model and amount of usage, you should change the fresh air filter every 3-6 months of operation.  As a good rule of thumb, TEL recommends replacing this filter with every oil change.   
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Front Blower Motor Recirculation Filter:   This filter should be checked frequently.  This filter may not be easily accessible, and truck manufacturers typically recommend this to be replaced at a service center, if you frequently use the recirculation function, replace this filter annually. However, if you have a pet that rides with you, the potential for pet dander and hair buildup in the filter is high. Therefore, consider changing this filter every six months if you have a pet.

Rear (bunk) Blower Motor Filter:  This filter check should be part of your daily check.  To check this filter, depending on your truck make/model, you may have to look under the bunk.  This filter is usually easily accessible for inspection and replacement. 

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According to the manufacturer's recommendation, this filter should be changed at every oil change. 

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Due to the location of this filter, it is important to keep the area inside the cab directly in front of the filter intake clear of any obstructions.  Blocking the airflow to this filter intake can starve the blower motor of air, potentially resulting in system failure. 

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Potential Issues from Neglecting Filters: 

Front Evaporator Freezing:  Operating with a clogged Fresh Air or Front Blower Motor Recirculation Filter can cause reduced airflow resulting in the front evaporator coil for the A/C system to freeze up.  If the coil freezes up, you may notice reduced cooling from the system or no cooling at all, as air can’t pass through the coil.  If this happens, you may also notice the A/C system stopping and starting intermittently.  Contact TEL maintenance or your service center if you experience these issues. 
frozen or dirty evaporator

Blower Motor Failures:   If either the Front or rear blower motor filters are clogged, or in the case of the rear intake being obstructed, the blower motor can overheat due to inadequate airflow.  Depending on your make/model, there is typically a resistor or relay designed to halt the blower motor if it becomes overheated.  If you continue operation under these conditions, this could result in component failure or permanent system damage. 


If you notice the blower motor stops functioning, first check for dirty filters or obstructions and replace them as necessary.  If no obstruction and filter are clean, contact TEL maintenance or your service center. 


Filter Collapse:  Dirty filters can become some clogged that they eventually collapse.  A neglected filter can also disintegrate over time.  If either of these conditions happens, this allows unfiltered air to reach the evaporator coil, potentially causing clogs in the evaporator coil and costly repairs.  An evaporator coil replacement can be as much as $2,000-$3,000. 


Maintaining your air conditioning filters is not just about comfort—it's about safety too.  It ensures that drivers are operating in optimal conditions, minimizing risks associated with fatigue.  As we journey through the summer months, take the time to inspect and replace your filters to ensure a cool, safe, and efficient drive. 

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