FREQUENTLY ASKED QUESTIONS

Why must refrigerant and lubricant be precisely measured during installation?

Due to exacting tolerances on today’s A/C systems, refrigerant and oil must be installed to manufacturers’ specifications to enter the compressor as a mist.  “Undercharging” or “overcharging” the system can under- lubricate the unit or “slug” the compressor, causing premature failures. ALWAYS recover, evacuate and recharge to OEM specs.

What is a "Liquid Charge"?

A "Liquid Charge" refers to introducing refrigerant to the A/C system in a liquid state as opposed to a gaseous (vapor) state.   This can result in a liquid refrigerant “slug” of the compressor, which can freeze and shatter the internal valves of the compressor.  This can happen in mere seconds.

What conditions cause A/C Compressor clutch failure?

• Bearing failure

• Incorrect air gap between the outer plate (hub) and the belt pulley  (normally .016 -. 030 inch)

• Electrical short in Coil, usually due to improper polarity or burnt winding

• Low voltage at coil (causes coil to overheat due to slippage)

• Locked Compressor

• Belt is wrong type or size; can also be misaligned or loose

What conditions cause A/C Compressor failure?

• Failure to properly Flush System: Compressors and other system components wear over time, causing residual debris to mix with the refrigerant and oil charge. This sludge can enter the compressor and cause it to seize.  Failure to properly flush or using flush that leaves residue behind is a primary cause of failure.  Note that many system components cannot be flushed and MUST be replaced

• Excessive High / Low Head Pressures:  Condenser fans can fail, causing heat buildup that can create excessive head pressure and damage or seize the compressor.  Faulty connections at the coil can cause high resistance and low voltage, resulting in clutch slippage.  Painting condensers will insulate the unit surface, inhibiting heat dissipation and increasing head pressure in the compressor

• Improper Refrigerant or Oil Charge:  Today’s compressors use less refrigerant and oil, and are extremely sensitive to inaccurate charging.  Installing an incorrect oil type can lead to lubricant breakdown in high heat conditions.  Overcharging of oil can cause blockages in the condenser, orifice tube or expansion valve and starve the compressor of oil

• Refrigerant Blends:  Impurities can affect seals and O-rings, causing them to leak, swell or otherwise deteriorate

What does humidity have to do with my air conditioner?

Your A/C system removes heat from the passenger cabin, and in so doing also removes moisture.   We are most comfortable in a climate where relative humidity is low, and the A/C system constantly works to remove moisture from the air.  Regularly check the condensation drain at the bottom of your evaporator and clear any blockage that may cause condensate backup.

What is "Black Death"?

“Black Death” is a result of catastrophic breakdown of the refrigerant and lubricant in the A/C system.   This breakdown causes excessive wear inside the compressor.  As a result, metal shavings and other particles combine with the refrigerant/lubricant mix to create a black residue.  The residue can contain solder flux from the condenser and aluminum shavings from the compressor.   When this mix cools, it hardens in the condenser and other system components.  Repeated flushing will not remove it.  If a failed compressor is replaced with only another compressor (and no other components, including the condenser) the remaining “black death” liquefies, flows through the system into the liquid line and blocks the orifice tube. With less refrigerant flowing past the orifice tube, the compressor is starved of lubricant and will lock up.

What does a Drier do?

Under normal operation, wear and tear will create debris that circulates through the A/C system.  Additionally, lubricant oil absorbs moisture that has accumulated in the system.   The drier (or accumulator) contains a desiccant that removes moisture, and also traps debris at the bottom of its tank style design.  Replacement of the drier or accumulator is a must when servicing your A/C system, and will assure better performance.

What is the benefit of flushing?

Oil, sludge and debris that is left in the system can restrict or plug the condenser, orifice tube or expansion valve.   Refrigerant and oil restrictions can damage or destroy the compressor.  Flushing before compressor replacement removes residual oil and debris from the previous compressor’s failure.

How are AC system leaks located?

With the engine not running, a halogen leak detector should reveal most A/C system leaks.  In many instances, however, leaks may occur only when the system is in operation.  In these cases, the insertion of a florescent dye can help locate the leak.   A UV lamp will ne needed to illuminate the leak, and the leak has to be where the light can reach it.  Many OEMs approve the use of trace dyes, and some have been inserting trace dyes on the assembly line. Dye can be inserted either during or after charging. The amount of dye used is quite small, and remains in the system even if the total charge is lost.

What does the most common A/C terminology mean?

Glossary of Terms:

ACCUMULATOR:   Filtering / moisture removing device located on           low side of system
BTU:   British Thermal Unit
AMBIENT AIR:   Natural environment; i.e., the air outside your car
CAPILLARY TUBE:   Gas-filled temperature sensing tube
CCOT:   Clutch Cycling Orifice Tube system; replaces TXV system
CLUTCH CYCLING SWITCH:  Evaporator temperature-controlled switch    that cycles compressor clutch
COMPRESSOR:    Pump that moves the refrigerant; “heart” of A/C system
CONDENSER:   Heat exchanger for refrigerant
DISCHARGE LINE:   Compressor outlet line
DRIER: Filtering / moisture removing device located on                            high side of system
EPA:   Environmental Protection Agency
ESD:   Electrostatic Discharge
EVAPORATOR:   Heat exchanger for passenger compartment
HEAT:    Anything above absolute zero contains heat
HEAT EXCHANGER:   Device for transferring heat
LIQUID LINE:   Guides high-pressure liquid through A/C system
MANIFOLD:   Connects suction & discharge lines to compressor
PAG:   Polyalkylene Glycol (lubricant used with R134a refrigerant)
PROM:   Programmable Read Only Memory; computerized control head
SUCTION LINE:  Line between evaporator outlet and compressor
TXV:   Thermostatic Expansion Valve 

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

Please refer to the description below each illustration.

TUBE and FIN

Oldest design still in operation.  3/8-inch diameter round tube condenser.  Acceptable for use with R12, but not recommended for R134a. Tube and Fin condensers CAN be flushed.

PICCOLO MULTI FLOW (tube inside diameter 6 mm)

Smaller, lighter and more efficient than 3/8-inch tube and fin or serpentine designs.  Popular in many ‘90s and up domestic vehicles. Piccolo 6mm condensers CAN be flushed.

SERPENTINE

All aluminum, more efficient than tube and fin.  Popular on smaller vehicles where space is limited. This type of condenser is very difficult to properly flush.   Serpentine condensers SHOULD BE REPLACED.

PARALLEL FLOW

 All aluminum, this efficient design breaks up flow into tiny streams that shed heat more rapidly. This type of condenser cannot be flushed.Parallel Flow condensers MUST BE REPLACED.

PARALLEL FLOW with SUB-CONDENSER

Oval tube, multi-flow and sub-condenser in stacked configuration. 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 cannot be flushed.   Parallel Flow / Sub Condensers MUST BE REPLACED.

Is static electricity a concern?

During the testing and repair of computer controlled vehicles, electrical components can be damaged or disabled by static electricity (also called ESD).  In fact, new electronic components can develop an internal static charge from contact with the package during handling.   Many technicians take the extra precaution of grounding themselves to the body ground of the vehicle. This can be accomplished by using a wrist strap that is available at most electronic supply stores.

Why is the type of oil used so important?

The moving parts of a compressor must be lubricated during operation. An overcharge or undercharge of lubricant can damage the compressor. Just as importantly, oil must be compatible with the refrigerant that carries it through the system.  Compatibility of refrigerant oil is determined by its ability to remain oil when mixed with the refrigerant and not become separated by a chemical reaction.  Today’s R134a systems use either synthetic oil (PAG) YN-12 or Double End Capped PAG oil.

• Remove all components to be replaced

• Flush all remaining components with appropriate flush solvent (note that many condensers cannot be flushed and must be replaced)

• Replace the Accumulator or Receiver Drier

• Replace the Expansion Valve or Orifice tube

• Replace manifold sealing washers or O-rings

• Use a Vacuum Pump (20+ minutes) to pull vacuum, remove moisture

• Add the proper amount and type of oil (check OEM specs)

• Rotate compressor hub 10-12 times to spread lubricant internally, oil the shaft seal

• Introduce external airflow to the condenser

• Check OEM specifications for correct refrigerant charge

• Charge with refrigerant, with A/C and engine off

• Leak test and check voltage at clutch coil

• Check belt tension and alignment

• Check system operation at 1500 RPM and mid-blower speed

• Use gauges to check system pressures

What causes reduced air flow from the A/C vents in my car?

• Low blower motor voltage due to a poor ground

• Blower wheel loose on motor shaft

• Defective blower relay

• Air leak or obstruction in air duct system

• Air mode door directing flow to the heater outlet

• Evaporator icing due to condensation

• Debris in evaporator housing that blocks air circulation

• Obstruction at the air return

Why is internal moisture harmful to my A/C system, and how does it get there?

Moisture can cause internal icing that obstructs the orifice tube or expansion valve. This can create excessive high pressure and reduced cooling.

Here's some ways that moisture can get into your A/C system.

• Service hoses left unevacuated after being connected to an A/C system will have air and moisture in them.

• Hoses left uncapped while replacing components allow moisture to enter.

• Refrigerant oil is hydroscopic (water absorbent) and will pull in moisture if left uncapped.

• Recycling machines with worn filters will not remove moisture from incoming refrigerant.

• Systems low on refrigerant will pull in moisture if they go into a partial vacuum.

What are the basic A/C systems?

ORIFICE TUBE (CCOT) SYSTEM

Orifice tube systems use an Accumulator located in the                            Low side of the system

EXPANSION VALVE (TXV) SYSTEM

TXV systems use a Drier located in the                                                            High side of the system

Are your compressors compatible with R12 or R134a refrigerant?

Every A-AirOnline compressor is remanufactured with Nitrile or HNBR seals, which allow compatibility with either R12 or R134a refrigerant systems.

Do your compressors come with a clutch?

All A-AirOnline compressors come complete with the clutch assembly. No compressor leaves our facility without the clutch assembly attached and fully tested.

Do you require a core charge?

A-AirOnline does not charge a core charge, a significant savings to you.  The price you see on the website is the complete price (excluding shipping or tax as applicable).  We may ask you to return your original units if the compressor you purchase is a hard to find core; we will send a prepaid UPS return tag with your compressor return so there is no cost to you.