polo91

My condensor was badly damaged so I have replaced it. The evaporator was removed cleaned and flushed along with the condenser. New o rings and r134a charging ports. New filter dryer. I plan on putting 8oz PAG oil in the system. Do I need to get oil out of the compressor. I don't see a sump or anywhere to add or drain the oil. Do I need new pressure switches? if so which ones. Lastly, the original capacity was 36 oz. of Freon. I have heard we should use about 10% less R134A. The roadster is not exactly air tight and living in East Tx I need to get this right. Any help would be much appreciated.

aklim

I'm going to be gathering the parts to do the swap since my compressor is noisy. Also looking into doing a new condenser since I am there to make the system more efficient.

polo91

Let me know about what you find out on condensors. A new one is hard to come by, I checked around and Ecklers can get one but it will take six weeks for the manufacturer to make it and the price is high. Will a 93-95 work? Are they diff because they are made for R134A? Also my parts guy sold me Ester oil, the 91 compressor is not made to use PAG oil.

billschroeder5842

Yes and no.

Condensers have no moving pieces and only serve to cool the fluids that travel through them.

Get yourself one that bolts in and you are good.

Patsgarage

Your original pressure switches will be OK, the running pressures of R12 and R134a are similar. If your system is open it is pretty easy to remove the compressor and drain it on a bench, but it is not necessary. The 10% rule is just a starting point, see how the system cools and adjust the charge as needed according to the running pressures.

confab

I had a series of similar questions earlier and Joe C linked this book in post #2.

https://www.corvetteforum.com/forums...requested.html

It is an excellent book and I would recommend it to anyone.

aklim

I'm not sure. AFAIK, they are on eBay. I don't see how a 93 will work since they went to R134A between 94-96

Yes, the R134A ones are thicker

aklim

True but is is as efficient as the R134A ones that are physically different (Thicker)?

polo91

About eight years ago I posted if you have an R12 system to stay with it and I did. But R12 has become expensive, hard to come by, and just a pain to deal with. I used some R12 substitutes but they were not satisfactory. When my condenser was damaged the change was made to R134A. The evaporator was removed and flushed with acetone as was the used condenser. The compressor was drained and a new dryer and orifice tube installed. Eight oz. of Ester Oil was added. The job wasn't really that difficult but I did have the use of a lift. Buttoned it up, pulled a vacuum, and put in the R134A and am well pleased with the results. With an outside temp of 95 and high humidity the vent temp runs between 50 to 57 degrees which works fine for the small roadster interior. It seems to run 50 to 54 below 1500 rpm and 55 to 57 above 1500.

I do wonder if the factory R134A C4s have a different condenser and does it fit my car? Also my wife drives an 05 Cadillac XLR (basically a C5 Corvette} and those temps are about ten degrees cooler. I would like to achieve that in my 91. .

By the way the whole job cost less than $200 including the used condenser, Walmart R143A was $4.88 a can.

Patsgarage

I am sure that others will disagree, but 50 deg is pretty good for a conversion. Remember, you are still using components designed for R12, so there will be a loss of efficiency. The main thing is not the temp, but how much humidity the system can remove. Glad to hear that everything worked out for you.

aklim

I'm looking to modernize my system to make it more of an R134A system by changing the condenser but I don't know if the compressor matters.

belairbrian

has anyone used the Spectra condensor? AZ shows them in stock.
I used a Spectra heater core, and it fit properly.

Patsgarage

Good question, I am not sure. A quick search shows the same compressor PN for both 93 & 96, so it may not matter.

polo91

AZ has the 91 condenser for $157 and the 94 for $250 so something is different.

-=Jeff=-

there are 2 different types of Condensers..
Tube and Fin, found on most R12 equipped cars.
Parallel Flow, found on Most R134a Cars.

In my 1990 when I got it, I ran R134a, but man could I feel the load running the AC. I was losing Refrigerant so I got another compressor, accumulator and a new Condenser, this time a Parallel flow one to replace my tube and fin. I cleaned all the lines out.. I put everything together, pulled vacuum and used R12. I barely have a load on the car when the compressor runs. on a 90 degree day I am just below 60deg out the vent.

Mind you this is a ZR-1, the compressor is a Nippondenso 10pa17, not the 10pa20 found in the L98/LT1 cars. so my compressor works harder and I have more heat from my motor.

Anyway, I would think the Parallel flow would help you.. In Fact I have often wondered if with that condenser I would be better with R134a

aklim

Any idea who would be the best to get a compressor from? Denso? Four Seasons?

Local2Ed

In my supply of R-12, I've bought 12 oz. cans from $8.oo per can to $25.oo per can. I would think fixing a leak, repairing what is needed, would be easier and cheaper than than a conversion and would work properly.

What does it hold, 3 cans at $25.oo per can.
You're looking at $75.oo for freon over the price of repairing the system which will have to be repaired no matter what you put in the system.

If repaired correctly, the R-12 should stay in the system a long time.

Patsgarage

I have had good luck with both brands, but for whatever reason most of the conversions that I have seen use Denso compressors. I have never heard a concrete reason why, availability maybe ?

aklim

Were they rebuilt or new?

Patsgarage

I buy new for all my cars, when it comes to all the work involved in evacuating/pulling a vacuum/charging an A/C system I try to minimize any chance of problems. Plus the price of refrigerant is getting higher and higher every time I buy it.