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Automobile Air Conditioning Questions & Answers

by: aircoparts( 1372Feedback score is 1000 to 4,999) Top 1000 Reviewer
149 out of 164 people found this guide helpful.
Guide viewed: 28403 times Tags: a/c compressor | accumulator | evaporator | auto air | auto a/c


Frequently Asked Questions

HOW DOES AUTO A/C WORK ?
Everything has a certain amount of heat except at absolute zero ( -460 degrees.F ). An ice cube May feel cool to the touch, but actually it just has less heat than your hand. That means heat is transferring from your hand to the ice cube. This is the principle behind how an A/C cools the air in a car. Heated air is forced across a cold evaporator and is transferred to the refrigerant gas, making the air less hot. The refrigerant carries the heat away from the evaporator to the compressor. The refrigerant is super heated by compression and is forced through the condenser where cooler outside air takes the heat from the refrigerant. Its next stop is the expansion device (TXV or CCOT) which meters refrigerant into the evaporator and we start over again. SIMPLE ISN'T IT !

WHAT DOES A DRIER DO- DRY?
IT'S NOT THE FREON!! It's the oil in the refrigerant that absorbs moisture and holds debris in the system. Replacing the drier / accumulator, in addition to evacuation, will assure better performance.

Why Replace the Receiver-Drier?
The receiver-drier must be changed each time a system is empty regardless of the reason for loss of refrigerant. It should also be changed every three years, because the desiccant pellets will break down and clog the expansion valve. This will in turn cause the system to become inoperable and May damage the compressor.

The receiver-drier is strictly a disposable item and is thought of in the same terms as a fuel, oil, or air filter. In fact, if any component fails or is replaced for any reason, the receiver-drier must also be replaced to prevent corrosion and moisture in the system.

The receiver-drier performs three functions:

-It filters the system of non-condensables.

-It receives the liquid refrigerant and maintains a certain level of liquid at the bottom at all times in a properly charged system.

-It contains a stack of pellets called desiccant (drying agent) to trap and absorb moisture. NOTE that moisture is the most harmful enemy of the air conditioning system. If any moisture is in the system, it will combine with the refrigerant to form hydrochloric acid which is extremely corrosive to metal components.

Replacing the receiver-drier is essential when servicing the A/C system. Whenever you replace a component of the A/C system you must also replace the receiver-drier. If you do not change the receiver-drier there could be serious damage to the other parts of the system, which could be very costly. You must also have proof of changing the receiver-drier in order to receive a compressor warranty.


WHY INSIST ON FLUSHING
There is no way to know how much oil is in a system
(1) Flushing eliminates excess oil from previous services. You do not want to add another full charge of oil when replacing a compressor and adding oil to the system.
(2) Sludge and debris, left in the system, clogs the orifice tube/expansion valve and can damage the valves in a compressor.

Q: Are Your Air Conditioning Parts Brand New?
A: We offer remanufactured (not just Refurbished) and new Air Conditioning compressors and clutches (all our other AC parts are typically brand new). You can find the part type (remanufactured versus new) on the product detail page.


Q: Can You Provide General Information On Auto Air Conditioning?
A: General information about auto air conditioning:

Accumulator
Accumulator is canister after the Evaporator. Freon expands dramatically when it is heated up as it passes through the evaporator in the passenger compartment, absorbing the heat and changed into gas. The accumulator receives the (R12 or R134a) in the gas state as it leaves the passenger compartment evaporator. It has desiccant to trap moisture.

Alignment - Belt
The engine belts that drive the A/C compressor must be in alignment. A reason for them to be out of alignment is that the pulleys on the A/C compressor do not match with the engine pulleys. This can be due to improper installation of engine pulleys or A/C clutches as well as incorrect brackets used in mounting the A/C compressor.

Charge, Re-Charge
This describes installing (R12 or R134a) into the A/C system. Usually charging a system means installing the proper amount of (R12 or R134a) into the system that it needs. Re-charging suggests that only a portion of the freon has been lost from the system and is being replaced. Recharging a system that leaks can delay repairs, and could be illegal in some states. If a system has lost all of its (R12 or R134a), recharging is never advisable until you find the cause of the leak and the leak is repaired. Open systems could have contamination of air and moisture that enters the system after the (R12 or R134a) pressure is lost.

Compressor
The compressor receives the Freon in a gas-like state and compresses it into liquid and circulates it into the condenser where the heat is taken out of the (R12 or R134a). The compressor is lubricated with special oil. It is very important to use the correct oil to the compressor and system. Some seals and gaskets May not work with some oils.

Condenser
The condenser converts (R12 or R134a) from the gas-state back to the liquid state. The condenser is a radiator-like unit made up of coils. It is often mounted in front of the car radiator. (R12 or R134a) comes into the condenser from the A/C

Contamination
A/C systems can be contaminated with metal particles from the normal wear of the compressor and tiny amounts of water moisture. Contamination can cause a system to fail. Protection against contamination is provided by the filter screen on the Expansion Tube and the desiccant in the bottom of the dryer or accumulator. Other forms of contamination May be the wrong kind of oil, wrong kind of liquid charge or other material that will interfere with the cooling system. Almost 100% of moisture is normally removed from the system when it is evacuated prior to installing (R12 or R134a).

Drier
Drier is used before the evaporator and after the condenser. The Filter Drier is where the system will filter out small amounts of contamination and moisture from the system. Each time the system is opened or worked on the Drier should be replaced. The desiccant inside the dryer will absorb moisture. Also spelled drier.

Evaporator
Evaporator is a small radiator like unit that is stationed inside the car, usually near the heater core. The Evaporator receives liquid (R12 or R134a) into its coils. The fan inside the car circulates hot air over the evaporator coils and (R12 or R134a) absorbs the heat and is converted to gas which then flows to the accumulator. The cooled air flows into the car.

Evacuate
In the installation or repair of your A/C you should be sure to use a vacuum pump to draw a vacuum on the entire system. Vacuum is usually measured at 29 inches. We recommend holding the vacuum for 2-4 hours without fluctuation (most industry sources suggest 30 minutes). The vacuum will extract any moisture from the system as well as provide some assurance against possible leaks.

Expansion Valve, Expansion Tube
Also called the orifice tube. This component often has a mesh screen and is found in the evaporator inlet pipe (liquid line). In some cases this item is found in the outlet of the condenser. Its purpose is to limit the flow of the high pressure liquid (R12 or R134a) and thereby meter the flow of refrigerant to the evaporator as a lower pressure liquid. The screen serves the purpose of trapping metal particles that break loose from the compressor or other components. Expansion Valve come in two types, Block and Right Angle. The block valve is located at the evaporator and its purpose is to constantly check the temperature of the (R12 or R134a) and allow the proper amount of (R12 or R134a) to enter the evaporator. The right angle valve comes in two types (internal equalized and external equalized). This valve is also found before the evaporator and its purpose is to control the amount of (R12 or R134a) going into the evaporator.

Fittings - Hose
A/C hoses are designed to control liquid and gas at high pressures and temperatures. The hoses are usually flexible and terminated with special metal fittings at the ends that prevent leaks and provide a sure seal and connection between components. If you see blisters or bumps on the hoses you have a leak. You have to replace the whole line because today we use hoses that have a liner.

Flush
During installation or repair of A/C systems, the system should be flushed with clean special purpose fluids prior to the Evacuation and charge with new (R12 or R134a). This process is critical to the success of the job and long life of the system. Flushing removes contamination such as particles of rubber or metal that could be harmful to the system.

R12 and R134A
R12 Freon has been used since the 60's in automotive A/C systems. Government regulations and increasing prices have made R12 to high of liquid to use today. R134a is the newer version of R12 with out the harmful effects to the atmosphere. R134a is a much smaller and more efficient than R12. R134a typically runs a higher head pressure and tends to leak out quicker from high side leaks than R12. R134a requires the that the best components are used in your ac system. In some cases you will need to replace your condenser and evaporator to a higher efficient model so that R134a can perform properly. Warning. Do not mix R12 with R134a. Make sure you use the proper Oil.

Leak Test
A/C systems sometimes develop small leaks just like car tires do. When a leak develops the A/C (R12 or R134a) can be lost over the course of a few minutes or a day or two. One form of leak testing is done by charging a system with dye. When the dye escapes, it leaves a colored deposit at the point of the leak. Another form of leak testing is done by a simple pressure test, however this kind of test rarely helps locate the point of a leak. Another is done with a electronic leak tester.

Oil PAG or Ester
Oil is designed to work with (R12 or R134a). Its primary purpose is internal lubrication for the compressor. A small portion of oil circulates through the system. Some systems collect the oil at the bottom of the accumulator and return the oil directly to the compressor through a separate line. It is very important to use the correct oil with the correct (R12 or R134a)

Pressure Switch
The pressure switch senses internal pressures and can cycle the compressor off and back on based on minimum and maximum pressure limits. Pressure switches also turn on or off you condenser fan or Radiator Fan.

Pressure Relief Valve
Relieves pressure from the system to protect components when internal pressures become too high.

Schrader Valve
This is the same kind of valve you have on your car tires and bicycle tires. It is used at one or two places in A/C systems to provide an access point to measure pressures and to remove or install (charge) (R12 or R134a) into the system.

 

Q: Do You Provide Any AC Installation Guide?
A: Working on any system you must make sure you do the following:
1.Replace accumulator/receiver drier. Contaminants accumulate here and you must replace these items. The desiccant bag in these components once opened will absorbed to much moisture and not work properly.
2.Replace orifice tube or check expansion valve for contamination.
3.The A/C system must be flushed or an inline filter must be installed. Flushing must include condenser and evaporator. IMPORTANT-Compressors contaminated with black oil or any foreign material will not be warranted.
4.When replacing a Ford built FX15 or FS10 or General Motors V5 compressor that has suffered a catastrophic failure, the condenser must be replaced. If the discharge hose assembly is equipped with a muffler, the hose assembly Must be replaced. This is due to the Teflon being disbursed throughout the system. (Black Death) When this happens the only way to get the Teflon out of your system is to replace the item. The Teflon only liquefies once it is heated and therefore you can not flush it out of the system.
5.The proper amount and type of lubricant for the system must be added. After installation, rotate the compressor shaft to ensure no liquid remains in the cylinders. This will lubricate all internal compressor components.
6.Charge the system with the proper amount and type refrigerant. Do not charge the system with pure liquid (R12 or R134a) this could cause the reeds in the compressor to break.

 

Q: How can I ensure effective operation and performance of the AC?
A: The following steps are highly recommended to ensure effective operation and performance:
1. Check operation of engine-driven fan clutch or electric radiator and condenser fan motor.
2. Check operation of clutch cycling switch or relay and all safety switches.
3. Check for proper operation of cooling system.
4. Check the external condition of the condenser (bent fins, road debris and leaks).
5. Check all drive belts and pulleys for alignment and wear.
6. Inspect Schrader valves and sealing caps. If retrofitting, install proper retrofit fittings.
7. Inspect all hoses and fittings for leaks and repair as necessary.
8. Evacuate system to 29.5 in. HG for 2-4 hours. The system must hold the vacuum before charging.
9. After charging the system, leak test and performance test the system.
10. It is always good to add the proper dye to the system incase you system develops a leak.
11. Check for proper operation of you heater control valve. A faulty valve will allow heat into you cab and will not let the evaporator work properly.
12. Check for proper operation of your fan clutch. If the fan clutch is not working properly your system will not cool down and thus your head pressure will be too high. This will cause the system not to work correctly and premature death of your compressor.


Q: How do you find A/C refrigerant leaks?
A: Two methods are commonly used. Dye and electronic. Dye is most popular but can take several days to appear. Many components are not visible so, the dye can often not be seen. Often shops charge for refrigerant and Dye and tell you to come back in a few days. This works but costs you time and more money for refrigerant. Electronic detectors are quicker to pinpoint leaks and minimize the loss of refrigerant.


Q: Is It Correct that 134A will not cool as well as R-12?
A: Thousands of cars and trucks have been converted. Feedback has been extremely positive. Slightly longer cool down times have been the only differences noticed by some customers. Some vehicles should not ever be converted. If you car or truck has a copper plate and fine condenser and evaporator we would suggest that either you switch out these components to a higher efficient model or return back with R12 into the system.


Q: My compressor leaks - must it be replaced?
A: Not always. If a compressor w/low miles leaks, quite often it can be repaired.


Q: What Does Your Warranty Cover?
A: 180 Days - 1 Year Warranty (parts only) except for Compressors. Compressor Warranty must have a proof of purchase of new dryer / accumulator. Note: 99% of all factory defects occur within the first ninety days of installation


Q: What Is The Model Number Of My AC Compressor?
A: The manufacturer name and the model number of your AC compressor can be found on the label of the compressor. Before purchasing an AC compressor, please match the model number with the compressor you want to purchase.


Q: What Is Your Return And Shipping Policy
A: Returns May be subject to a 30% restocking charge plus shipping. Only returns submitted within 10 days from date of invoice May be returned. No returns without prior authorization from the Supplier (see Contact Us page). Online orders May be cancelled prior to shipping without any charges.


Q: What does it cost to retrofit my car to 134A?
A: There is no set price for every car. On major repairs, such as compressor replacements, it can be less expensive to convert vs. recharging with R-12. Your primary concern should be to find out exactly what has failed on your system.

AIR CONDITIONING PARTS
• 1. Compressor Assembly
• 2. Accumulator/Drier
• 3. Expansion Valve
• 4. Fan Clutch
• 5. Blower Motor
• 6. Radiator/Condenser
• 7. Heater Control Valve
• 8. Hi Pressure
• 9. Evaporator
• 10. High pressure Lines


Guide ID: 10000000000932422Guide created: 05/11/06 (updated 09/15/08)

 
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