System Flushing

iklan bawah share

Automotive air-conditioning system flushing has become in recent months a very controversial subject. A lack of guidance and commitment from OEMs regarding flushing and the varying opinions from industrial bodies have left the aftermarket with no conclusive flushing method or flushing procedure. Consequently, the end user is left bewildered and/or unprepared to make a decision on the best flushing method available and service to offer his customers. 

Autoclimate, an aftermarket supplier, has considered all OEM methods and procedures, taken into account numerous industry opinions and subsequently developed a liquid refrigerant flushing procedure, which minimises valuable labour time and at minimal cost to the end user.

An automotive air-conditioning system may require flushing for several reasons: 

1. Retrofit (conversion from R12 to R134a).

2. System contamination.

3. System component failure. 

Retrofitting is the name given to a procedure that involves converting an R12 automotive airconditioning system, which uses refrigerant R12, into a system that uses refrigerant R134a. Consequently any R12 system which needs repair must to be retrofitted to R134a, if system longevity is to be considered. System contamination is a phrase that covers a wide scope of potential issues. System contamination is considered when any other substance outside design parameters has been introduced into the A/C system. Debris, burnt lubricant, contaminated lubricant and incorrect lubricant are some of the issues that need to be considered when system contamination has occurred.A low system refrigerant charge will result in poor lubricant circulation, thus increasing friction and heat causing premature system failure. Increased friction and heat will also begin to burn the system lubricant causing it to carbonise inside components, on pipes, seals etc. 

Debris is usually the result of a system component failure, this can vary from fine metal particles to desiccant, a result of a receiver-drier/accumulator failure. Once this debris has begun to circulate in the system, it must be removed. Irreparable damage and expensive repairs are a direct consequence of debris in the A/C system. Debris passing over ‘burnt’ lubricant will begin to adhere to it, and slowly a blockage may form. In these instances the system must be flushed to remove all debris. 

The lubricant must also be flushed from the system and the correct amount and viscosity added; if the flushing procedure and lubricant renewal are not carried out correctly it might result in a repeat failure.The build-up of lubricant/debris can also affect the heat transfer characteristics of both the condenser and the evaporator. Modern condensers and evaporators have multipath parallel circuits, so the possibility of clearing every path that is blocked is unlikely, thus affecting performance. In these instances it may be necessary to remove and replace the component. A similar effect may be experienced if the system has too much lubricant, although flushing will remove excess lubricant. 

Flushing method

The flushing procedure may be carried out in a closed loop configuration (with the system split in two halves) or each individual component separately. Flushing each individual component can be labour intensive and expensive for the customer. Closed loop flushing with liquid refrigerant is a quick, effective method of flushing, which does not introduce any foreign chemicals to the system that may lead to further problems.The flushing process can be improved by 

the introduction of an oil-based cleaning agent. The introduction of oil-based cleaning agents greatly improves the first time removal of oil and debris from the A/C system. By allowing the A/C system to be split into two halves, high side and low side, an effective forward/backward flush can be achieved. Any restrictions in the system, such as the receiver-drier, expansion valve, accumulator or orifice tube, are bypassed. Adaptors have been developed which allow for most restrictions to be bypassed; a set of universal adaptors may also be used for less common vehicles. 

Results

Once the system has been successfully flushed and all contamination/debris removed the system may be reassembled. It is recommended that the receiver-drier/accumulator is always replaced after flushing an A/C system. With the A/C system cleaned, increased heat transfer should result in improved system performance. No contamination, the correct viscosity, and the correct amount of lubricant in the system will ensure that the compressor also operates to system performance expectations. 

iklan bawah postingan iklan bawah related post