1984 C4 120,000 miles - bought last year - Doing everything on the front of the engine that leaks, P/S pump, water pump, timing chain. It's so apart right now that I want to put it back together with the right compressor & condensor for R-134a to save work later. The existing system has a freon line that wore through from rubbing on the upper control arm so it's been open for who knows how long. Compressor turns free by hand but who knows? Condensor is smooshed fin-wise in the front, beyond straightening (I tried).

So since I have to replace the condensor anyway thought I would try to get one for R-134a. Have seen posts that R-134a uses a parallel flow condensor that's more efficient than the R-12 condensor. Have seen generic 134a condensors at ACKKITS.com.

Does anybody know of a source for an R-134a condensor to fit the car?

Saw an Ekler's kit for $289 - new compressor w/clutch & valves, o-rings, accumulator. Looked like a decent deal, all in one package. Figured if the filter/orifice is all in one piece the evaporator is probably clean so I'll change most of or all of the hoses, all the o-rings, flush it & it should be ready for vacuum, charge, etc.

 

You're smart to change the Condensor to one for 134a because the 134a condenser uses multiple rows of very very tiny orifices compared to the very large radiator like orifices the R12 condensers have.

I recently had my AC serviced at an AC specialty shop and they showed me a cut away of the different condenser designs (R12, Import size and 134A).

An AC Specialty shop can custom fit a 134A condenser and also, fabricate the hoses and fittings.

 

Eckler's @ $189 http://www.ecklers.com/corvette-air-...1984-1985.html

 

Condensor is a questionable upgrade. The real problem is keeping it under control at higher ambients - 90 plus degrees - when R134 can build some unrealistic pressures. The OEM's do it by turning the coolant fan on sooner; ie, at much lower pressures than the design of your system. Your Harrison R4 compressor has a pressure switch in the rear head ('84 only) that's closing the fan relay at about 230 psi. Ideally, you want the Main fan cranking below 200 psi for R134, but unfortnately, I don't know of any source for a different switch. Most try to overcome the situation by using 75 to 80% of the R12 fill. That doesn't always work and when it's 90 plus you start pushing so much pressure (often it's sprialed into the 300's) that the low side hovers around 50 psi. At 50 psi, R134 is boiling at 54 degrees and with super heat, you end up with 60 degrees out of the vents. The best solution is to simply stay with the R12 fill. Get you license at www.epatest.com and buy all you want now because realistically, no one wants the stuff.

 

Ii agree with SunCr- get your epa license, buy R-12- lots on ebay, some local auto parts stores still carry it. And rebulild your old compressor- seals, bearings, O-rings are all still available and it's an easy job!
Hve fun!

 

My recently purchased 84 has an A/C that is not working. The other complication is I am in Australia.

In the above post freon, R12 and R134a have been mentioned. Are these all different? What gas did the 84 A/Cs come out with? Haven't looked into A/C before but am keen to get it running.

 

pmihaltian, I saw that condenser at Ecklers but it didn't say that it was an R134a type. Is it and how could you tell?

 

SunCr, I could put a 12vdc relay in paralell with the compressor clutch power to start the fan whenever the compressor is on I think. A lot of older systems worked that way stock. Although I hate to say that I gave away about 15 Lbs of R12 2 years ago to a friend after it sat in my basement for like 15 years. I thought I would never need it again....

 

Run the fan all the time and when it's 70 degrees or lower, the compressor will cycle off as the high side won't be able to push enough to keep the low pressure contacts closed. That's why a switch, keyed to pressure, is so much better. Our stuff is antiquated compared to what's being used now - basically a variable stroke compressor that uses a bellows to match pressure to demand so there's no Low Pressure Switch and no cycling - but you still have to keep the charge within a relative range, so a Pressure sensor matchs the coolant fan even more precisely. I'd work with what it's got.

 

Lemme, Freon R12 was used in all cars (and refrigerators in stores, like soda cases) here in the US until around 1993 so your 1984 came with R12. R12 was the sort of refrigerant which would punch a hole in the ozone layer so R134a was made as a replacement. R12 is no longer a mainstream refrigerant, R134a is. I would assume that you have a similar story in Australia.

Both R12 and R134a are used for car AC & refrigerators because their boiling point (the temperature that they will boil at in the evaporator coil when cooling your air) is fairly low, in the 40's (F) so you can get discharge air in the 40's which is needed with the high glass area and poor insulation of a car.

For instance, R22, used in houses and for commercial comfort cooling, boils in the 50's so it provides a discharge air of around 55 deg F which is suitable for comfort cooling because 55 deg F air at 100% relative humidity coming off of a cooling coil for a house (yes, if an AC unit is dehumidifying the air leaves the coil at 100% relative humidity), when warmed to 73 deg F as it is in the occupied room being cooled, has a relative humidity of about 53% which is perfect for people.

So different refrigerants are made to have diferent boiling points for different appications but here in the US for cars it has only been R22 and now R134a.

 

OK, SunCR you are starting to make me think I should stick with R12, but if the compressor goes off on low suction pressure isn't that what the CCOT systems of the 70's did (thinking 1978 Monte Carlo), they abandoned the expansion valve for a fixed orifice and just cycled the compressor - which I always thought was a little brutal on the clutch & compressor.
So was this 1984 system an improvement on CCOT by keeping the fan off until the head pressure went up so the compressor could stay on or at least run much longer cycles?

 

To me, yes, as long as the charge is right, it's going to stay on long enough to maintain a fairly even vent temp and cycle very little between 50 and up (and even below 50 degrees, some engine heat will eventually keep it cranking). Its also a good way to let you know, without burning it up, that it's low on gas. GM, I think, was the first to switch to this system and in fact, Chrysler was still employing an expansion device (and maybe still is - the last Soccer Mom Van I worked on had one). I'd prefer GM's current unit which was tried/tested and broken on a ton of crap (Gran Prixes and similar rental car fare) before making it onto the Vette, and if there was enough demand (apparently there isn't), the aftermarket would probably have embraced it and we'd all be slapping one on. Of course, the hybrids/electrics will bring this full circle though getting the compressor off the accessory drive train is probably a plus. In any event, you have the knowledge to make it the way it left the Factory so that's what I'd do - shoot, you only need 4 cans (at most) and gas, regardless of what you use, is still the cheapest part of your build.

As to our member in Australia - as I understand it - R12 is banned in your Country and can't be imported (and the last time I was through your Customs, they did a pretty good job of checking my stuff so I wouldn't think of trying to bring some in).

 

If you have a choice between R12 and 134a, I would stay with the R12 system which will perform better with the stock AC components.

Just have a reputable AC shop do the work and your AC system should be good to go for many many years.

 

Some universal condensers here. No affilation however I have used their products on numerous custom installations with excellent results.

http://www.vintageair.com/catalog10/...Page%2076).pdf

If using a stock condenser & converting to 134 suggest installing a pusher fan in front of the condenser. Use a relay for the fan, trigger the relay with the compressor clutch feed.

Install a blue orifice valve.

The above worked well in all my 134 conversions or new installations while in S FL. No complaints about warm register air while idling in traffic.

Vehicles with engine driven fans can sometimes get good ac results with a fan blade change & a shroud for the fan. A 7 blade with 2 & 1/4" pitch will draw plenty of air at idle.

 

Thanks for the heads up.

 

Thanks. I am sure you are correct. Probably hasn't been converted yet. I will check for any labels. First thing I need to do after that is work out whether the system is functional. Compressor doesn't kick in. Have to press in the schrader valve to see if there is any gas pressure too.

 

I purchased this condenser last year when I rebuilt my A/C system. The Eckler's condenser came with tags on it that said R134A. However, I kept the system stock and refilled with R12. The system and the A/C are working fine.

 

Still have not started on my air conditioning & won't 'till spring and have not decided R12 or 134a yet but look what I just came across on E-bay - a fan cycling pressure switch for 134a! A month or so ago I tried to find one, even in the Grainger catalog, thought something for commercial AC might work but there was nothing.
http://cgi.ebay.com/ebaymotors/1984-...Q5fAccessories