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Air Conditioning System Replacement Tips

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  • Air Conditioning System Replacement Tips

    This kind of repair involves more than just an R&R of a damaged compressor, since the old refrigerant must be removed from the system and stored in a proper container. Also... once the new compressor is installed, the system MUST have a near perfect vacuum established or the A/C will not ever cool properly. To avoid any woes (Whoas!) for your A/C repair, here are some suggestions for the fix that are "The Universal Baker's Dozen of Auto A/C Repair" :

    1. Change the Accumulator at the same time the Compressor is swapped out. The reason is because the PAG oil that lubricates the system passes through the accumulator along with the return line refrigerant vapor and nested deep inside of the aluminum canister should be a packet of Silica Gel that acts as a hygroscopic sponge to absorb any traces of moisture/water vapor. As soon as you open any A/C system... ambient air loaded with water vapor will migrate not only into the Silica Gel pack,,, but the PAG oil will also sop or sponge up all the available moisture by literally yanking out of the exposed air. In short...any moisture not captured by a bone dry accumulator will freeze somewhere down in the lines and plug everything up with ice.

    2. If you are NOT going to flush the A/C lines with the old compressor removed to flush out any residual dirt or metal particles from a FUBAR'd compressor... just cap all the lines as soon as you loosen and remove them to prevent the introduction of atmospheric air and non-condensable gases. Don't flush the A/C with the old compressor installed... all you will wind up doing is forcing more of any left over metal mung from inside the busted compressor deeper inside the liquid and vapor lines and have that crap lodge inside the evaporator coils and condensing coils units. Take the time and modest expense of flushing the lines of all this junk and the system will work better and get much cold(er).

    3. Replace the pale green "O"Rings on all fittings with those of an exact thickness and diameter. If you use the ones that come from Autozone...there might be enough variation for them NOT to seal ...since they tend to be thinner and less "beefy" than the factory ones. You can use the old ones in a pinch as long as they show no signs from pressure erosion, wear or tearing. Just clean the interfaces between the hose piping fittings and lightly lube them with some fresh PAG oil. Be sure to recap your bottle of PAG oil...or it will be useless in twenty minutes from water saturation if left open to the air. Go light on the torque...these aluminum fittings and hosing are very touchy to accidental damage...its the "O"Rings that do the sealing... not excessive pressure on them from their fittings.

    4. Before you install the new compressor... follow the manufacturer's recommended amount of PAG oil to be poured in. As a general rule of thumb... You should pour two (2) ounces inside the compressor and two (2) ounces inside the new accumulator...and sometimes it calls for two (2) more ounces to be poured inside the top of the condensing coil before the A/C Vapor Return Line is buttoned up at the top of the condenser coil.

    5. *** It is very important to make sure you HAND TURN THE COMPRESSOR BEFORE INSTALLING THE PULLEY/SERPENTINE BELT(S) AT LEAST TEN (10) COMPLETE REVOLUTIONS, This will cycle the PAG Oil properly, correctly distribute the lubricant and prevent the compressor from hydro-locking. Then just install the Serpentine or V-Belt(s) and prepare to vacuum down the system. This is all done AFTER you attach the A/C hose manifold just after the compressor is bolted properly in place. A flashlight, mirror and 3/8" drive with long extensions will also help you down there, too.

    6. It is worth it to head over to Harbor Freight and buy a 2.5 - 3 CFPM Vacuum Pump for around $150.00... If you own more than one car with A/C problems... fixing them yourself will surely recoup the $$$ with this item on hand. The important thing about the pump is that it be of the scroll design and be able to pull a double vacuum down to about 25 microns. It Is more important to use the most refined Vacuum Pump Oil that you can buy (about $7.00-$10.00 a quart and available via eBay) than it is to have a super-expensive unit like a Robinair or a Yellow Jacket Vacuum Pump pulling 6 CFPM). Harbor Freight also sells an inexpensive set of Auto Refrigerant Gauge Manifolds with all three pressure lines and High/Lo quick connectors, too.

    7. After the proper vacuum period... anywhere from 30 minutes to a few hours depending upon how long and how open the system was prior to this repair... then its time to introduce the R-134A refrigerant into the clean and vacuumed system. This coolant should only be put into the system through the LOW SIDE (BLUE FITTING) LARGE CALIBER ALUMINUM LINE. NEVER install the gas from a can by just turning it upside down and allowing it into the LOW SIDE as a LIQUID! And likewise...NEVER allow either refrigerant vapor or liquid to be filled on the HIGH SIDE SMALLER CALIBER LIQUID LINE (RED FITTING). People have been killed when trying this and holding a can that exploded in their face because of excessive high pressures involved during compression. Only charge R-134A on the LOW SIDE fitting!

    8. Don't be too macho about not wearing eye protection and heavy leather gloves while charging the system. If the lines or can should leak, burst or break and this super-cooled liquid splashes in your eyes or on your hands and arms...it will instantly freeze and permanently destroy those tissues. Be Careful With This Stuff!

    9. After a proper vacuum of the system... With the engine OFF.... If you are not using your own A/C Manifold Gauge Set... Then use the type of service unit that comes with a built-in hand-squeeze control valve and its own Pressure Gauge to screw into the top of your various cans of R-134A and use the short hose Quick Connector valve and attach it to the LOW SIDE (BLUE) A/C Service Valve. Tighten down the connector. Then, start the engine at idle and turn on the A/C settings to HIGH COOL with the air blower set on HIGH. Slip an inexpensive analog A/C Thermometer inside one of the center vents to measure the temperature drop.

    10. Don't be alarmed if the A/C compressor clutch does not instantly cycle on ...With the engine turned off, you will have to allow at least one can of R-134A to get inside the system and distribute itself for ten minutes or so. Then start the car and see if the LOW PRESSURE CUT OFF VALVE goes into detente and allows the compressor to engage with the electromagnetic clutch. With enough R-134A to get the pressure up, it will cycle on and off rapidly until there is enough coolant in the system to keep the clutch running continuously. As the freon gas is going into the LOW SIDE LINE service valve... move the can from the 12:00 to 3:00 position and shake it gently to stimulate the liquid to vaporize sooner and enter the system. DON'T BE TEMPTED TO RUSH THIS PROCESS BY TURNING THE CAN UPSIDE DOWN... If you do this...you could "SLUG" the compressor and damage it badly since the COMPRESSOR IS DESIGNED TO COMPRESS VAPOR...AND ALL LIQUIDS ARE INCOMPRESSIBLE!!!

    11. Allow the system to normalize for three to five minutes after each injection of R-134A and prop the can/hose into the upright position if you are SOLO when checking the thermometer and feeling for changes in the interior of the car with all windows closed. AVOID PUTTING IN TOO MUCH REFRIGERANT! R-134A does not cool as efficiently as R-12 used to and Autozone sells a small yellow container of extra PAG Oil and a "Freeze Helper" that can make a big difference. This small can of stuff goes in EXACTLY like the regular cans of R-134A and at the very same LOW SIDE PORT (BLUE)

    12. If you have to resort to using the small can of Special Sealer to stop any leaks that happen afterward, MAKE CERTAIN TO IMMEDIATELY PUT THE R-134A CHARGING HOSE RIGHT BACK ON AND PUMP SOME MORE FREON THROUGH THE SERVICE VALVE OR THE SEALER WILL PERMANENTLY PLUG UP THE SERVICE PORT!

    13. KEEP YOUR COOL...and lay out your tools, parts and lubricants in an organized way and this job will be a BREEZE! Wash your hands and do NOT get any PAG OIL on your skin or in your eyes. This stuff is very irritating to them.... and with all that said....Best of Luck!
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