DIY Network

A/C Retrofit -- Introduction From "Weekend Mechanic" episode WKM-110

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Bruce Bonebrake diagnoses and repairs problems with the air-conditioning system on this 1984 Chevy Corvette. Modern auto air-conditioning systems no longer use freon. A/C systems in many older cars can be upgraded so that they meet current EPA requirements. In this episode, an older Corvette gets an a/c-system upgrade with a retrofit kit that will permit the use of the latest approved refrigerant -- R-134A. Figure A Figure B Figure C Figure D Figure E Figure F

AC Retrofit -- Introduction

In this episode, Weekend Mechanic Bruce Bonebrake diagnoses problems with an air-conditioning system on an '80s-era Corvette. He then replaces a faulty air-compressor and related parts and upgrades the a/c system on the vehicle so that it can use R-134A refrigerant and meet current EPA standards.


The problem: Our project car, a 1984 Chevrolet Corvette, has an air-conditioning system that has stopped cooling. Causes of the failure may be include a system is low on (or completely out of) refrigerant, a system leak, a clogged condenser or a failed compressor.


DIY Difficulty Rating for Repair: This job is not as difficult or complex as many people might think. We gave it a difficulty rating of 2 on a 5-point intermediate-level scale. Depending on the nature of the problem, this job might be finished in a single day. Allow yourself a whole weekend, though, to allow for any possible complications.

Important: Included below are the steps in this automotive procedure as shown in the episode. These steps are general guidelines that are applicable to most vehicles. With any particular vehicle, there may be procedures, specifications, settings, tolerances, components, etc. that are specific to that vehicle. There are also variations according to the type and brand of a/c retrofit kit you select. Always consult your vehicle's service manual when undertaking significant automotive repairs, and read and follow the directions and precautions that come with your a/c kit.

In addition to standard auto-mechanic's tools, some of the specialty tools required for this repair (figure A) may include:

A/C vacuum system including pump, hoses and dial meters
Valve-core remover
Flush solvent
Dye cleaner
Refrigerant retrofit kit

These materials should be available at most auto-parts stores.

R-12 refrigerant was the standard type of refrigerant on cars manufactured before 1994. The cost of recharging an R-12 based a/c system is at least $150. The kit to upgrade our a/c system to R-134A was only $40. For most pre'94 vehicles, it makes good sense to retrofit the a/c system to R-134A refrigerant.


Diagnosing the Problem

• To find the source of the problem, Bruce switches on the a/c system (figure B) while the car is running. The blower fan is operating, but the system does not cool.
  
  
  
  
• Listening to the system, there is no audible click when the switch is turned on. A click would indicate that the compressor-clutch has engaged. The absence of the click is a good indicator that the compressor may be the source of the problem.
  
  
  
  
• With the hood lifted (figure C), the a/c compressor is located. As with most vehicles, the Corvette uses a belt-driven compressor that is operated by an electromagnetic clutch.
  
  
  
  
• With the engine turned off, the compressor (figure D) is inspected, and checked to see if the clutch turns freely. Since the clutch cannot be readily turned by hand, there is a good possibility that the system has lost its refrigerant. Typically, when an auto a/c system loses its refrigerant, the compressor also loses its mineral-oil lubricant. This causes the compressor to seize up and quit operating.

  Note: A/C systems never use motor oil as lubricant.
  
  
  
  

• Upon close inspection, it is evident that the front seal on the compressor has failed, and the compressor has lost its lubricant.
  
  
  
  
• The a/c system also uses a clutch-cycling switch located near the compressor (figure E).
  
  
  
  
• When pressure gets low in the system, the clutch-cycling switch (figure F) prevents the clutch from engaging. It evidently did so in our case. The switch will need to be replaced as part of the repair.

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