Chevrolet Cobalt Service & Repair Manual: 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. |
|
Compressor Hose
Caution: Use the correct fastener
in the correct location. Replacement fasteners must be the correct part
number for that application. Fasteners requiring replacement o ...
Refer to Fig. 1
for ambient air temperature sensor service.
Fig. 1 ...
Air Conditioning Refrigerant Line R&R
Ambient Air Temperature Sensor R&R