Importance of Flushing


To minimize the risk of a repeat compressor failure, technicians should also do everything they can to protect the new compressor from contaminants. Compressor failures often throw a lot of debris into the condenser, but some of it can also blow back up the suction hose. For this reason, some manufacturers recommend flushing out the condenser and hoses, installing an inline filter to trap debris, and an inlet screen in the suction hose to protect the compressor.

Flushing is also a controversial subject because the vehicle manufacturers do not agree on which technique works best or even if it works at all. Ford approves flushing with VSL338 terpene-based solvent while GM says its okay to flush but only with R134a, no solvents. Chrysler and Toyota do not recommend flushing. If the system is contaminated and contains debris, Chrysler says it is safer to replace the condenser and hoses. Flushing may dislodge most of the debris in a serpentine flow condenser, but does not work very well in parallel flow condensers.

Parts proliferation continues to be an ongoing challenge for the aftermarket. Twenty years ago, there were half a dozen different basic compressor designs. Today the number has grown to over 1800 and will top 2000 before the end of this year!

Refrigerant contamination is another problem the industry faces. In 1997, the MACS field survey found 2.3 percent of A/C systems were contaminated with air, other refrigerants or hydrocarbons. In 2000, the number jumped to 5.3 percent. This underscores the need for shops to use refrigerant identifier equipment do check vehicles prior to servicing them. MACS says 71 percent of their member shops are now using an identifier to prevent cross-contamination.

Why Flushing should be part of your Regular Service Procedures.

You know that not all A/C jobs are simple recharges. There are times when you need to flush a vehicle's air conditioning system to ensure that it operates satisfactorily. Basically these circumstances fall into three categories:

  1. Routine Maintenance: Typically the older a system is, the more problems may occur. As an air conditioning system ages, oil, sludge and particulates can build up, plugging screens, expansion valves and capillary tubes. Periodically, you should flush the system to remove the contaminants to keep the system operating efficiently.

  2. Repairs: To be sure the system will operate properly, you should flush whenever you repair or replace components. Failed components may contain metal shavings, sludge and other debris that can damage the system.

  3. R-134a Retrofits: In many cases, conversion procedures call for complete removal of existing oil in an A/C system before recharging with R134a. Flushing is the most thorough means of removing the oil and it will also pick up any refrigerant residue in the system. Flushing combined with pulling a deep vacuum is your assurance the system is ready for the new refrigerant.

How many different condensers are there, and which can be flushed?

R-134a condensers have more fins/inch than R12 condensers and their fin diameters are smaller (6mm).

TUBE and FIN - Oldest industry standard, 3/8-inch diameter round tube condenser. Ok, for R12 but not recommended for R-134a.
This type of condenser is flushable.

6mm PICCOLO Multi-flow: Smaller, lightweight and more efficient than 3/8-inch tube and fin and serpentine. Used in many domestic OE applications.
This type of condenser is flushable.

SERPENTINE: All aluminum, more efficient that tube and fin, used on smaller imports where space is limited.
This type of condenser is not easily flushed. replacement is recommended.

PARALLEL FLOW: All aluminum, this efficient design breaks up flow into tiny streams that give up heat more rapidly.
This type of condenser is not flushed. replacement only.

PARALLEL FLOW with SUB Condensor. Oval tube multi-flow and sub-condenser stacked up. Refrigerant flows through the multi-flow into the drier (called a modulator) then continues as a liquid into the sub-condenser.
This type of condenser is not flushed. replacement only.




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