Porsche P-80 2005, Manual

Page: 88 / 108

Page 5.10
Climate Control Systems Diagnosis & Repair
A/C Refrigerant System Service & Diagnosis
Leak Detection
A/C refrigerant leaks can be small and difficult to locate.
Not all components are easily accessible and any
component in the refrigerant circuit can potentially leak.
When checking for leaks, pay close attention to
connections, o-rings and seals.
Electronic leak detectors can detect very small leaks for
both R-134a and R-12 refrigerants. The detectors emit an
audible signal when refrigerant is sensed. Refrigerant is
heavier than air, so always place the probe under the
component or connection when checking. Evaporator
leaks can be checked by probing a low point, the
evaporator moisture drain.
Electronic leak detector sensitivity can be affected if the
sensing tip is saturated with refrigerant or oil. Fluorescent
dyes can be injected into the A/C system. The dyes mix
with the system PAG oil and circulates with the oil. Oil may
escape along with the leaking refrigerant and carry the
dye along with it. An ultraviolet light (black light) causes
the dye to glow and can help to locate the leak.
Warnings and Cautions
When servicing and repairing automotive climate control
systems, you are exposed to several personal safety
hazards. Be sure that you review and understand these
potential hazards.
Porsche Repair Information contains a list of safety
precautions and warnings. Read and understand these
warnings and cautions before starting diagnosis or repair
work.
Observe the following precautions:
• Automotive air conditioning systems and service
equipment are under pressure and refrigerant can spray
unexpectedly. Refrigerant temperatures may be very
high or low, creating the risk of burns or frostbite. Be
sure to wear gloves and eye protection conforming to
ANSI standard Z87.
• Never open a charged A/C system before recovering
the refrigerant. An operating A/C system can generate
pressures up to 34.5 bar (500 psi).
• Work in a well ventilated area. Refrigerants R-12 and R-
134a both displace oxygen and are a suffocation
hazard. Refrigerants are heavier than air and can collect
in low areas with poor air circulation, such as under the
vehicle.
• Do not heat charged air conditioning system
components to temperatures above 80° C (176° F).
Pressure increases from high temperatures may cause
the system to burst.
• Store refrigerant containers at temperatures below
50° C (122° F). When charging an A/C system, do not
heat containers with an open flame. Use only warm
water to raise the temperature of refrigerant containers.
• Before welding or soldering A/C components, recover
all refrigerant and flush the system with nitrogen. Refrig-
erants decompose with heat and produce corrosive
substances. A pungent odor indicates that these
substances are present. Do not inhale. They can cause
respiratory problems.
• Although refrigerant R-12 is not combustible, it
produces poisonous phosgene gas when burned. Do
not smoke where refrigerant vapor may be present. R-
12 entering the engine's air intake will likely be burned
in the combustion chamber.