Top Tips for Servicing Engine Cooling Systems

Nissens take us through the ins and outs of servicing automotive climate systems with the latest in their engine cooling solutions

Most modern vehicles are now equipped with air conditioning systems. Knowledge and expertise of the core conditioning system components provide a competitive advantage in the automotive aftermarket. Nissens is recognised as a leading expert in engine cooling solutions and air conditioning (AC) with 95 years’ experience. They are able to provide a complete thermal know-how and manufacturing experience to guarantee that your climate systems are kept up to speed.

We spoke to Nissens to give us a run down of areas to pay attention to when servicing Climate Control Systems.

Servicing the Compressor

During an AC cycle, the compressor enables the refrigerant to change its state from gas to liquid and flow through the different components of the system as well as through the high and low pressure sides. Servicing the compressor correctly is therefore a crucial element to the efficiency of the AC system.

Hidden Condenser Issues

As one of the AC components closest to the external environment, condensers experience extensive wear and tear during their lifetime. Since roads are covered in salt during the colder months of the year, saltwater will spray onto the exposed condenser and increase the risk of corrosion in the system; thus reducing the efficiency of the AC system and increasing the workload, affecting other AC system components.

Main Effects of Condenser Corrosion

• Deterioration of condenser fins – resulting in condenser leakage, causing a reduced working surface area and thus a significant reduction in the heat exchange capacity.

• Lack of fins – resulting in a significantly less effective condensation process and causing the compressor to overload.

• Leaking condenser – as a result of the destabilised condenser structure caused by a lack of fins.

The condenser will begin to lose its cooling capacity as the refrigerant starts to disappear, causing the compressor to overheat. It is advisable to always mount a corrosion-protected condenser as saltwater tests show that they offer up to eight times longer lifespan than non-protected condensers. Over 500 of Nissens condensers offer this enhanced corrosion protection.

System Lubrication

The most critical aspect of compressor service and installation is ensuring the correct lubrication is applied. The most common lubricant used in modern automotive air conditioning systems running on R134a and R1234yf refrigerants is PAG oil. It is a fully synthetic oil that offers efficient and universal lubricating parameters. It is conductive, highlyhygroscopic and is available in several viscosity versions (46/100/150). Alternatively, PAO oils such as PAO68, is a non-hygroscopic formula that acts as an alternative to all the PAG versions. Although the characteristics of PAO and PAG seem similar, their viscosity parameters are different. Therefore, when conducting climate system servicing, ensuring you have the correct oil is a very important to the functioning of the compressor.

Incorrect Lubrication

A common reason for AC compressor failure is the use of the wrong oil type and viscosity. If incorrectly used, the wrong oil mixture will not penetrate parts precisely and the friction will cause the compressors to overheat and seize.

To ensure easy installation, Nissens compressors are pre-filled with PAG oil of the right quantity and viscosity.

The double end-capped, chemically inactive and stable PAG oil offers exceptionally good lubrication characteristics, high moisture tolerance at high temperatures and does not react chemically to form harmful acids or compounds.

Using the right Additive

As all moving parts are fitted with millimetre precision, every aspect of the cooling system setup is expected to perform within the boundaries of an exceptionally narrow margin. Part of this setup is the use of additives to enhance the properties of lubrication, essential for all movements of the compressor. Factors must be careful when dealing with additives, as incorrect use can make them extremely harmful to compressor lubrication.

Problems with Additives

There are three particular problems that are likely to to occur when dealing with additives:

Too much UV Agent

This will dilute the oil; resulting in improper viscosity and in turn, poor lubrication and increased pressure in the system.

Flushing Agent Residues in the System

This can impair the Teflon coating in the compressor, especially if the system is not thoroughly flushed afterwards. Teflon deterioration causes particles to peel off, eventually clogging the system and causing the compressor to seize.

Leak-Stop Contaminated Oil

Incorrect vacuum removal can leave moisture in the compressor system. As some leak-stop agents work by crystallising moisture in leakage areas, a poorly vacuumed compressor will experience extensive crystallisation. This will result in contamination of the circuit, reducing the lubrication abilities of the oil, causing the compressor to eventually seize.

Not Forgetting the Receiver Drier

Another AC product which is a crucial area to explore when servicing the climate system is the receiver drier. Located in the high-pressure side of the system, usually between the condenser outlet and the expansion valve inlet, the receiver driers primary function is to receive and store some liquid refrigerant from the condenser. Furthermore, the receiver drier acts as a temporary storage container for oil and refrigerant when not needed for system operation. Therefore, replacement of this part is essential when servicing the system and a must when replacing key AC components such as the compressor and condenser. The Nissens receiver drier range covers more than 800 OE numbers.

Nissens Quality Promise

To ensure that everything performs to the highest standards, Nissens conducts advanced life and performance tests as well as back-to-back tests against OE units. This ensures that every single product in Nissens’ range fully matches the OE equivalent. Furthermore, critical components, such as the pulley, clutch hub, bearing and wobble plate, are improved to withstand higher stress, tensions and temperatures than expected of OE units.

'First Fit' & 'First to Market'

Nissens focus heavily on added features of their range including quality, ‘First Fit’ and ‘First to Market’. With Nissens First Fit products in range, we can now offer everything that is needed to service your climate system by supplying all the necessary items in one box. This means that no extra elements will have to be purchased or fitted, providing garages with a quick and trouble-free installation. What’s more, Nissens First to Market promise ensures that the UK motor factors are always well-informed on the latest market trends.


We partner with leading manufacturer Nissens to offer a new high-quality range of engine cooling solutions and air conditioning parts to keep your climate systems in order.

• Nissens AC range covers more than 9,600 OE numbers.
• O-rings and pre-filled PAG oil available on all compressors.
• Nissens offers corrosion protection on 500+ of its condensers.
• All parts are manufactured to match OE specifications.
• Products are ISO9001/TS16949 and ISO 14001 certified and Ford Q1 approved.
• Fast delivery: same/next-day delivery guarantee.


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