Automotive Air Conditioning Information Forum

All of the corvettes of that era around here seem to have a first generation 6mm piccolo condenser.

What you are describing sounds like a blocked parallel flow condenser. High pressures with poor heat rejection - all of the refrigerant going through a few open channels.

I used to see a couple of Manitoba cars every summer. Sadly the A/C always seemed to be hacked up. Sealers, way too much oil, shoddy 134a conversions. I heard the words Canadian Tire often enough. My father in law would come visit from Winnipeg & bring a car that needed repair every year. All of his friends had cold A/C - one car at a time.

Check all of the hard lines for obvious damage. This is a high side problem.

I don't know much about Redtek R-12a and have never used it, but I understand that charging a system with R-12a requires roughly one-half the original R-12 amount. Your Corvette's specs call for 44 ounces of R-12 and 8.0 ounces of mineral oil. Did you reduce the R-12a charge accordingly?

JohnHere wrote:I don't know much about Redtek R-12a and have never used it, but I understand that charging a system with R-12a requires roughly one-half the original R-12 amount. Your Corvette's specs call for 44 ounces of R-12 and 8.0 ounces of mineral oil. Did you reduce the R-12a charge accordingly?

yep.

Even tried pulling the charge down to closer to specs and the compressor will start short cycling. Basically, slowly pulling it down to the point where it would short cycle and no difference in cooling (non) performance at any pressure.

I'm getting to the point where I'm just going to pull it all apart, MEK everything and replace anything that seems suspect. Replace the receiver dryer on spc, since I have no idea how long it sat in a "flat" condition...

bohica2xo wrote:All of the corvettes of that era around here seem to have a first generation 6mm piccolo condenser.

What you are describing sounds like a blocked parallel flow condenser. High pressures with poor heat rejection - all of the refrigerant going through a few open channels.

I used to see a couple of Manitoba cars every summer. Sadly the A/C always seemed to be hacked up. Sealers, way too much oil, shoddy 134a conversions. I heard the words Canadian Tire often enough. My father in law would come visit from Winnipeg & bring a car that needed repair every year. All of his friends had cold A/C - one car at a time.

Check all of the hard lines for obvious damage. This is a high side problem.

No idea what brand the condenser is. It's oem, original from what I can tell. I suppose it could be something in the system clogging it up, especially in pone of the cores. This car has had a good 30 years of owners before I bought it last year. Everything looks original, but there's no telling what someone might have shot in there. I suppose someone could have even tried one of those "seal in a can" things and buggered up something like the condensor or evap core.

Probably pull the condensor core and flush it on the bench, just because I'm going to have to pull it all down again anyways, Can't hurt at this point I suppose.

No obvious damages to hoses anywhere.



Anyone have any tips on getting those aluminum fittings apart?

I've tried before and they're all frozen (corroded?) in place. I don't want to be replacing hoses and lines, assuming you can even get them anymore....

One of the problems with keeping the right tools & parts out of the hands of home mechanics - is "magic in a can" . I found plenty of that.

If you have a 6mm Piccolo condenser, you can't flush it. Modern parallel flow condensers have multiple paths. One can be completely blocked, and your flushing agent will blow through whatever is left open.

Aluminum fittings can be a pain. A good penetrating oil like Kroil, soak time & heat offer the best chance of success. Letting the penetrant work for a day or two, then heating the part to 300f or so will break most of it loose. Condenser fittings should be steel nuts & aluminum block.

The accumulator with aluminum nuts and tubes from GM in those years can be impossible to separate cleanly. It can come down to which part you want to replace & splitting a nut or destroying a tube. On GM pickups often an accumulator meant replacing it AND the evaporator.

you might want to use an infared thermometer and "shoot" the condenser in various spots to see if it is indeed plugged. As for aluminum fittings, sometimes you can drill a small hole in the nut, squirt Kroil I them and let them sit. And them use more Kroil multiple times. Praying helps.

bohica2xo wrote:One of the problems with keeping the right tools & parts out of the hands of home mechanics - is "magic in a can" . I found plenty of that.

If you have a 6mm Piccolo condenser, you can't flush it. Modern parallel flow condensers have multiple paths. One can be completely blocked, and your flushing agent will blow through whatever is left open.

Aluminum fittings can be a pain. A good penetrating oil like Kroil, soak time & heat offer the best chance of success. Letting the penetrant work for a day or two, then heating the part to 300f or so will break most of it loose. Condenser fittings should be steel nuts & aluminum block.

The accumulator with aluminum nuts and tubes from GM in those years can be impossible to separate cleanly. It can come down to which part you want to replace & splitting a nut or destroying a tube. On GM pickups often an accumulator meant replacing it AND the evaporator.

Thoughts for the condensor was to pull it off car, set it face down, fill with MEK and cap the lines. Let it sit a couple days and then dump it out. I’m assuming the MEK can dissolve whatever it finds in the core.

I’ve got a new accumulator on its way, so the oem accumulator may meet a sad fate in order to get it out of there. On this car, its a lot easier (and cheaper) to replace the accumulator instead of the hoses. The hoses are hard to find and super expensive when you can. Definitely want to save them if at all possible...

Post a picture of the condenser when you get it out.

bohica2xo wrote:Post a picture of the condenser when you get it out.

Had a peek through the rad/condenser shroud and I'm pretty sure it's the piccolo one.

If it is, I'll give it a try to flush/clean it, but I may end up just replacing it. Assuming I can find one that will fit in the original hole. Seems most guys that have replaced a c4 condenser have had to go to a newer type, which is smaller than the oem....

6mm pic.

https://1800radiator.com/ProductImages/ ... 19DC92.jpg