Chevrolet Cobalt Service & Repair Manual: Air Conditioning System Leak, Inspection

Chevrolet Cobalt Service & Repair Manual / Air Conditioning & Heater / Component Replacement & Adjustment / Air Conditioning System Leak, Inspection

A visual inspection must always be performed to confirm the presence of aftermarket components, potential collision damage, or areas of concern. With the oils used for R12 systems, leak areas often collected much dirt and would build up sometimes large displays of road grime. R134a PAG oils do not collect nearly as much debris, and as such make visual detection much more difficult. It is still worth doing a visual inspection however.

Electronic

Caution: Always wear safety glasses when working on or near the A/C system.
First inspecting the air conditioning system with an electronic leak detector may yield faster results and avoid having the customer return to the shop once again for leak evaluation and then potentially a third time to have components installed.
Electronic leak detectors have a poor reputation in many repair shops. Their reputation as not being accurate is derived from poor maintenance practices, a poor understanding of how the tool works, and a lack of diligence in using the tool. Electronic leak detectors are extremely accurate tools that are specifically made for detecting hydrocarbons. However they can be very finicky to operate and must be well maintained. Always maintain tool as described in the manufacturer operating manual.
Many electronic leak detectors contain filters, desiccant, or moisture traps that need to be maintained periodically. Not performing regular maintenance on your electronic leak detector will also render it less accurate.
Electronic leak detectors can be very useful for hard to detect leaks such as those from an evaporator core. Leak detection dyes can be difficult to use in locations such as evaporator cores because of ease-of-access issues. Utilizing an electronic leak detector can lead to a faster, more accurate diagnosis.
1. Move sensing probe very slowly in area of a potential leak.
2. As refrigerant is heavier than air, it is important to move sensing tip of tool underneath sources of potential leaks.
3. Ensure tip of tool should never contact any components and must be kept very clean.
4. To find possible leaks at evaporator core proceed as follows:
  a. Turn AC system on medium high with windows and doors of vehicle closed.
  b. Let system run for five to ten minutes.
  c. Shut blower motor off and leave doors closed for five minutes.
  d. Inspect for a leak at evaporator box drain hose.
  e. While opening door and placing sensing tip at vent with blower on low speed can help identify other evaporator leaks.
  f. Once leak has been detected repair system as required.
  g. Be sure system holds vacuum before refilling.

UV Chemical Dye

By far the most popular method of leak detection is the use of chemical UV dyes, where a dye is inserted into the refrigerant system by itself, mixed with a small charge of refrigerant, or with a light quantity of refrigerant oil. A black light and/or special goggles are used to see the dye glowing at the leak location. The test is performed under full pressure with the air conditioning system closed.
Some refrigerants have UV dye already mixed from the manufacturer. In these cases, dye injection will not be required.
Caution: When injecting dye into pressurized system, always wear UV safety glasses and gloves.
Caution: Never use the UV light without wearing UV glasses.
Caution: Do not use UV light near flammable materials, liquids or gasses.
Warning: Never breathe refrigerant vapors.
1. It is important to eliminate any air in injector adapter hose before injecting dye into A/C system. Purge air as follows:
  a. Hold cartridge upward while unscrewing cap.
  b. Snap hose assembly onto cartridge and snap a suitable A/C system coupler on other end of hose.
  c. While holding assembly upward, attach handle to bottom of cartridge by turning it clockwise. Continue turning as dye enters hose and pushes air upward.
  d. Repeat this process as required until dye appears at couplers end.
  e. Remove coupler from hose assembly.
2. Turn A/C system and engine OFF.
3. Connect injector to low side service port of A/C system.
4. Hold body of injector, use starting line on handle end as a guide.
5. Turn handle clockwise to inject one application of dye (approximately 1-11/4 turns for concentrated dye).
6. Disconnect injector from system and clean any excess dye left around service port.
7. Turn engine and A/C system ON.
8. Allow sufficient time for dye to circulate throughout system.
9. Turn UV light on and search all tube joints and components for a bright green or yellow glow where system is leaking.
10. Once leak has been detected repair system as required.
11. Clean area around leak after repairs are completed.
12. Be sure system holds vacuum before refilling.
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