jagvette

Hey guys and girls

I have an 88 C4 and I am going to convert the A/C from R12 to R134a I have the adapters and the R12 system is empty I have all the tools for R134a but do not know how much R134a I should use to get the correct level does any one know, also I will replace the drier and hoping there is nothing else I need to replace unless you guys/girls know different.

Any help will be gratefully received.


Gary alias Jagvette

Gunho

I believe the new dryer doesn’t have the low charge valve on it. You will have to replace the low pressure line with one with the valve. Don’t forget to add the refrigerant oil too. System holds around 3 small cans of 134

65Z01

A little yellow tracer would be good for future leak detection.

Are you also replacing the evap. valve?

Patsgarage

Standard rule of thumb is to use 75-80% of the R12 charge.

jagvette

good point

jagvette

that sounds like a good idea is this something that must be done, my knowledge of A/C is limited.

jagvette

OK, do you happen to know how much R12 the system originally had ?
,

jagvette

yes I will put oil in, but doesn't the r12 to r134 have the adapter valve ?

Gunho

Yes there are adaptor valves. But if you change the dryer, the new dryer won’t have one on it as they moved it to the hose on newer systems. Could be different on your year. But they did on my sons 93. As the valve was on the dryer.

Patsgarage

There should be a sticker under the hood listing the factory charge. IIRC my 89 is 44oz of refrigerant/ 8 oz of oil.

Maldini

Is there some sort of cleaner to run through an r12 system before converting to r134, or is it just a matter of the system being empty and that's good enough?

puterami

Yes, there is an A/C flush. You should use the "pop" method to try and clean out the evaporator.
Take off the compressor and drain it.
Take off the condenser and drain/flush it.
Replace all of the old hoses.

Also, change out all of your o-rings to the green RES style. And, if you did not know, mineral oil is not compatible with R134A. You need to use a PAG oil or a new type of ester (compatible with both).

Benny42

None of the OEM A/C unit manufacturers (non-automotive) recommend any of the flush products. The flush kits are designed to remove residual
mineral oil from the system but a few percent mineral in the system is less damaging than any residual flush left in the system from an inadequate
evacuation. Blow out all the residual oil with nitrogen (or air if you have to) and put in the proper oil. Evacuate and charge to 80% of R12 capacity.
Then enjoy the chill.

BLKMAMBA

I did mine on my 93.