Common Issues With Proair LLC Systems And How To Diagnose Them & Choose The Right Shop

Proair LLC Systems Common Issues

Specialty heavy duty trucks require systems that help the engine and other parts of the commercial vehicle stay cool. When these parts overheat, it could lead to serious and costly damages. Proair LLC systems are commonly used when adding an HVAC solution to heavy duty trucks, but there are a couple of common issues that you may experience with these. We’ll take a look at common problems that can occur with these systems and ways you can diagnose the issue at hand. This post also explores ways in which you can choose the right repair shop for your trucks. 

Common Proair LLC System Troubles

When operating a fleet of heavy duty trucks, it’s common to choose options that use the Proair LLC system to cool down important parts. While these systems are made from quality parts, they can sometimes give you problems. Let’s consider a few common symptoms that you may find and what you can do. 

Main Blower Motor Won’t Work

If the main blower motor in the Proair LLC system fails to work, then it could be due to a circuit breaker that broke down, a bad connection in writing, or a malfunction in the fan motor. Sometimes, the motor switch malfunctions or the resistor wiring breaks off. You should inspect the circuit breaker and the wires that are connected to the blower motor to determine where exactly the problem lies. 

Wiring issues may simply need to be corrected, and sometimes, resetting the circuit breaker helps. In cases where there are malfunctions or broken parts, a replacement will usually be necessary to get the blower motor to work properly again. 

Insufficient Airflow

Sometimes, you may find that the main blower motor works fine, but there are some problems with the airflow produced by the system. There are a couple of reasons why this can happen, so you’ll need to inspect the blower inlet, the case joints in the cooling unit, the hose, and the switches in the system. 

Possible problems affecting your system can include an obstruction in the evaporator inlet, an air leak in the cooling unit’s case, and a defective thermostat switch. In some cases, the duct hose may be turned off or damaged, which can also have an impact on how efficient the airflow in the system is. 

Poor Cooling Capabilities

When the motor blower works, and there is efficient airflow, but the system is not offering enough cooling, then it might be due to the refrigerant. Refrigerant leaks are generally the most common reason why the cooling capabilities of the system do not comply with the requirements of the heavy-duty truck. In these cases, the leaks need to be addressed, and the refrigerant system may need to be recharged. 

The problem is not always with the refrigerant. You should also check the water valve, as well as the cable that is attached to it. When there are problems with the connection or position of the water valve cable, it could interfere with the system’s ability to keep the truck cool. Additionally, sometimes the water valve gets damaged, in which case you may need to replace the valve in order to restore adequate cooling functions.

Problems With The Condenser Fans

The condenser fans also play an important role in ensuring the cooling system works as expected. Sometimes, the condenser fans won’t kick in, which could cause weird noises or even lead to insufficient cooling, increasing the risk of certain parts overheating in the heavy-duty truck. 

There are several reasons why the condenser fans may fail to work. If the clutch slips, for example, then you should check the coils and battery voltage. Note that this only accounts for cases where your heavy-duty truck uses a magnetic clutch. It’s also possible for the drive belt to become loose, or a malfunction may develop in the internal compressor. When the internal compressor malfunctions, you’ll likely need to replace the compressor to restore the functionality of the condenser fans. 

You should also not overlook the possibility of bad wiring or broken wires. You should closely inspect the wires that are connected to the condenser fan motors. Make sure you also inspect the connections of the drier-mounted relay. Repairs can sometimes help to fix these issues, but sometimes the wires may need to be replaced. 

Tips For Picking The Right Repair Shop

Troubles with your Proair LLC system in a heavy-duty truck can be alarming and increase the temperature of various parts in the vehicle. When you face these troubles, it’s often not possible to go about the repair process as a DIY project; instead, you’ll need to find a reliable repair shop. 

With several repair shops to pick from in Chicago, it’s not easy to find one that meets all of your needs. Here are a few tips that can help with your decision-making process:

  • Don’t be hasty and rather take your time to review the different repair shops in your local area. Consider asking around for referrals and looking online to see what people are saying about the repair services offered by repair shops that are in your local area. 
  • Try to get quotes from more than one repair shop. It’s a good idea to use three quotations to compare both the services and pricing among these shops. 
  • Talk to the mechanics and other industry experts at each of these shops. Tell them about the problems you have with the Proair LLC system and see what they say. Compare the expertise presented by each professional. 


If your truck uses a Proair LLC system, then you need experts who are experienced in working with these HVACs to service and fix common issues. At Bus & Truck of Chicago, we have the expertise needed to effectively assist with repairs to Proair LLC systems, regardless of the troubles you are facing. We work closely with you to provide a professional and friendly service while also keeping our prices competitive. To schedule a repair, simply get in touch with our office. 


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