Question: Converting a 93 R12 A/C system to R134a

[azdawgfan]

Are there any issues I should be aware of when I convert to R134a. The condenser sprang a leak and will have to be replaced and of course the accumulator-dryer will be replaced along with the expansion valve. Are the hoses OK? Can the compressor handle R134a?

 

[boomdriver]

Are there any issues I should be aware of when I convert to R134a. The condenser sprang a leak and will have to be replaced and of course the accumulator-dryer will be replaced along with the expansion valve. Are the hoses OK? Can the compressor handle R134a?

I think the BIG problems with 134a conversions are not fixable, so its a matter of financial/convenience vs effectiveness.

I converted and did it by the book. My system even with a new condensor will cool well with ambients of 95* with 80+% humidity as long as I'm moving so there is good fresh air across the condensor. The system is inefficient with 134a.
I know of 134a factory cars that will put frost on the inside of the cabin under the same conditions. The difference is a bigger evaporator, more efficient condensor and a higher vol compressor,. Remember that our Vettes have no frontal area to collect and inhale fresh air...we have to be moving to scoop air otherwise we're dependent on the sucker fan to pull enough thru. Those with a pusher fan MAY get a slightly better cooling when that fan finally comes on. I've considered installing another pusher to run whenever the a/c is running...just to move some air on the condensor.
I'm also seriously considering going back to R12 since the price of gas has dropped to a "street" price of 35 to $50 per lb. When I converted it was closer to $75 and climbing...that and t he fact that my lil brother has around 15 lbs sitting in his stash of commercial a/c supplies..

So, IHO, if you live in moderate weather, go ahead with what you have listed. Hoses are good unless physically damaged, the compressor should be ok unless its worn and rattling, and that can be determined by the amount of trash found in the expansion valve. New dryer, and flush the condensor and evap thourghly ( and do it again) and evacuate. The evacuation of a 134a conversion is critical because even a small amount of free moisture will raise the boiling pt of the 134a to the point that it does not cool well with 75-80 degree ambients. New O-rings everywhere.

134a is just not as efficient as R12....I'd say about 10-15 degrees less. Even more on paper according to charts. Use care when filling with 134a as its better to be a little low. When its too full or over charged that too raises the boiling pt. Proper fill is approx 90% of what r12 was...so charge to about 75% and then add by the oz and check the outlet temps to see when you get to a good temp that you can live with. When it starts to go up again, stop filling and even let some out. 134a charging must be done with gauges and the low pressure is very important. Although the high can be dangerous its the low that determines how good the cooling will be.