DIY Network

A/C Retrofit -- Parts Removal and System Flush From "Weekend Mechanic" episode WKM-110

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Figure A Figure B Figure C Figure D Figure E Figure F Figure G Figure H Figure I Figure J

With the diagnostics performed on the Corvette's a/c system, the repair work gets underway with removal of some of the a/c components and a system flush. Later, the faulty a/c compressor will be replaced.

Safety Alert: Always disconnect the vehicle's negative battery cable before you begin engine or electrical-system repair work.

Accumulator, Drive Belt, Compressor and Hoses

• With the faulty seal on the compressor, not only has the refrigerant leaked out, but air and moisture has been allowed to infiltrate the system.
  
  
  
• The accumulator is a part of the a/c system that helps to remove and dissipate moisture from the system. The accumulator (figure A) has a metal exterior and contains chemical desiccant that removes moisture. With the system exposed, the desiccant becomes saturated, the containing bags can rupture, and the desiccant material contaminates the system. The accumulator will be replaced as part of this repair.
  
  
  
• The orifice tube, located in the liquid line, regulates the flow of refrigerant gas through the system. Whenever replacing a compressor, the orifice tube should be replaced also.
  
  
  
• For the Corvette, the first step for accessing the a/c work-area is to remove the air-filter housing.
  
  
  
• In order to work on the compressor, the a/c system must already be discharged of any remaining refrigerant.

  Important: The use of R-12 refrigerant is regulated by the EPA. Never work on an a/c system that still contains it. Releasing R-12 is harmful to the environment. Have a certified a/c-repair shop remove and capture the refrigerant.
  
  
  

• The drive belt must be removed (figure B) before the compressor can be removed from the vehicle.
  
  
  
• Inspect the drive belt once it is removed. In our case, the belt was cracked and worn (figure C), so it too will be replaced as part of the repair.
  
  
  
• With the belt removed, disconnect and remove the accumulator (figure D).
  
  
  
• With the accumulator out, unbolt the compressor's retaining bolts, disconnect the electrical wires, unbolt any support brackets and carefully lift out the compressor (figure E).
  
  
  
• Important: Always remove the compressor before flushing the a/c system. Flushing the compressor could cause debris to lodge in the oil channels, bearings or shaft seals.
  
  
  
• After the compressor has been removed, take out the orifice tube (figure F ). The tube contains a filter that will likely be contaminated with metal shavings and other debris. The orifice tube cannot be cleaned, so it will need to be replaced.
  
  
  
• Important: The two ends of the orifice tube are not the same (figure G). When installing a new one, be sure to orient it properly. Refer to your vehicle's repair manual for proper installation.

• The next step in the procedure is to flush the remainder of the a/c system, including the condenser unit and evaporator core. Flushing the system is important, since it removes any residue or contaminants that could damage the new compressor once it's installed. Also, since this repair involves upgrade from R-12 to R-134A refrigerant, the new system will use a different type of lubricant. It's important to remove any of the old lubricant that remains, since the two lubricants are not compatible.
  
  
  
• To flush the system, use a funnel to pour flush solvent into the condenser (figure H) and the evaporator. Make sure that the flush solvent that you're using is compatible with the a/c system your vehicle has. A/C flush-kits are available at auto supply stores.
  
  
  
• Once the solvent has been introduced, an air compressor is used to evacuate the solvent and contaminants from the system. The air compressor is equipped with a fitting that allows the pressure-hose to be connected to the condenser line (figure I). If you don't have an air compressor, you can achieve the same results with two to three cans of compressed air.
  
  
  
• The flushing procedure removes a substantial amount of contaminant particles, including the old mineral oil and loose desiccant material (figure J).
  
  
  In the segment that follows, the faulty compressor and other parts are replaced.
  
  
  

RESOURCES :

The Complete Idiot's Guide to Trouble-Free Car Care
Author: Dan Ramsey
ISBN: 0028635833
Alpha Books

Auto Repair for Dummies
Author: Deanna Sclar
ISBN: 0764550896