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Discussion Starter · #1 ·
Its not for the Z06, Its about my 1992 Isuzu Rodeo (beater)...

I had a friend that works in ACs charge up the AC unit, It seemed to work but who knows since it was getting night fall and cooler that day, then I tried to work it yesterday and never blew out cold air...

The unit says R-12 but my friend used some 134 (or something like that) on it and said it would be fine, but is that the problem?

thanx luis
 

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When you change over from R12 to R134a, you need to install a new expansion valve. The two coolants operate at different pressures. R134a being higher. Sometimes just charging with 134 will work, sometimes it won't. It sounds as if you have a leak. I'd look into that first.
 

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Discussion Starter · #3 ·
PerforminNorman said:
When you change over from R12 to R134a, you need to install a new expansion valve. The two coolants operate at different pressures. R134a being higher. Sometimes just charging with 134 will work, sometimes it won't. It sounds as if you have a leak. I'd look into that first.

True, It could be a leak, and being a 14year old truck who know all thats wrong, but if it had a leak wouldnt it take some time to leak out? or at least while operating? It ws charged on Thursday, never used until I turned it on yesterday and nothing :roll:
 

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I have an AC I am working on now. It will stay charged for a few hours but leaks overnight. I'm putting a seal kit on it today. If the system has been leaking for a long time, replacing the dryer/evaporator is a good idea.

Btw, R134a has shot up in price. It's not $10 a can and was just $5/can a little while back.
 

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BASIC R12 TO R134a RETROFITTING

INSPECT SYSTEM If the system to be retrofitted is operational, a performance test is necessary. If the system is not operational, determine what repairs are needed to bring the system to O.E. operational specifications.
RECOVER ANY R12 IN THE SYSTEM Remove all R12 refrigerant using approved recovery equipment. When complete, the system must hold a vacuum for 5 minutes. if the system shows a positive pressure after 5 minutes, repeat the recovery process.
REMOVE THE R12 MINERAL OIL* It is recommended that R12 mineral oil be removed from the system being retrofitted. This can be accomplished by draining individual components or by approved flushing systems.
REPLACE THE ACCUMULATOR OR RECEIVER-DRIER Remove the used accumulator or receiver-drier and install a new replacement unit that contains desiccant designed for R134a systems. Use R134a compatible O-Rings during installation. These are included in the Retrofit Kit.
PERFORM SYSTEM REPAIRS Make necessary system repairs. check the condition of expansion valve, orifice tube and pressure switches. If hose replacement is necessary, use only barrier type hose with beadlock fittings. O-Rings should be replaced with R134a type (included in kit). Check engine cooling system performance (Radiator, fan and shroud).

INSTALL AN IN-LINE FILTER If the compressor is replaced, installation of an in-line filter on accumulator type systems is required to protect the compressor warranty.
HIGH PRESSURE CUT-OFF SWITCH Installation of a high pressure cut-off switch may be necessary on some vehicles to insure compressor durability.
INSTALL R-134a SERVICE PORT FITTINGS Installation of R134a service port fittings is required by law. These fittings are included in the Retrofit Kit.
APPLY R134a LABEL Complete the sky blue retrofit label (included in the Retrofit Kit) and affix in a prominent position in the engine compartment. This is required by law.
ADD R134a LUBRICANT Add the correct amount of Castrol Retro™ A/C lubricant (included in the Retrofit Kit) for the particular system that is being retrofitted.
EVACUATE THE SYSTEM* Evacuate the system for 30 to 45 minutes.
CHARGE WITH R134a* Determine the correct charge for the system being upgraded to R134a use. In most cases, the R134a charge will be 15% less than the R12 charge.
PERFORM LEAK TEST Leak test the system using equipment that will detect R134a refrigerant.
ROAD TEST THE VEHICLE A 3-5 degree Fahrenheit increase in duct outlet temperature is not unusual. Adjusting the clutch cycling switch to reduce the cutoff pressure by 2 pounds (maximum recommended adjustment) or the installation of an auxiliary condenser fan may be necessary to reduce the duct temperature on some vehicles.
 
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