1988 corvette, don't understand what it's doing?

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Cusser
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Re: 1988 corvette, don't understand what it's doing?

Postby Cusser » Sat May 16, 2020 7:25 am

Hmmm - sounds like TOO MUCH refrigerant from your pressures??? I have no experience with that refrigerant; RedTek is R12a.

This link states that it will require only about 35% of the same charge as R12 to get the same (or most likely better) results. https://www.allpar.com/forums/threads/m ... re.161197/
tourmax
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Re: 1988 corvette, don't understand what it's doing?

Postby tourmax » Sat May 16, 2020 7:45 am

Cusser wrote:Hmmm - sounds like TOO MUCH refrigerant from your pressures??? I have no experience with that refrigerant; RedTek is R12a.

This link states that it will require only about 35% of the same charge as R12 to get the same (or most likely better) results. https://www.allpar.com/forums/threads/m ... re.161197/

good theory, except I pulled it down to where the low side was so low it started short cycling and the high side still stayed high with no change in cooling.
tourmax
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Re: 1988 corvette, don't understand what it's doing?

Postby tourmax » Sat May 16, 2020 7:50 am

So I'm sitting here thinking about this.

When the system was non operational, I did throw a quick can of top up stuff in the system to at least see if it ran. It did and it even frosted the low line, although minimal change in the vents.

I starting to think whats wrong here has to be something I touched.

that's the compressor rebuild and the orifice tube.

I think the smartest way to attack this is to go back and make sure those two items aren't a problem somehow (clogged, contaminated, etc) and then go into the system in general.

I have pulled the compressor back apart to check it already and I'm fairly certain it's correct. That means I should probably pull the orifice tube back out and check it. I did get it from the GM dealer by the vin number, so it SHOULD be the correct piece.....although that's no guarantee these days. An orifice tube not working properly or plugged could present the problems I'm having since it's where the high pressure enters the evap core. One that's not working could explain why the high side is going so high when the low side is so low it short cycles. It also does seem to hit the high pressure cut out if I leave it run long enough. Starting to sound more and more like it might be the new orifice.....
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bohica2xo
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Re: 1988 corvette, don't understand what it's doing?

Postby bohica2xo » Sat May 16, 2020 9:19 am

If the compressor will push 400 psi, the pump is not the problem.

Red trash refrigerant does not even publish an MSDS for their product. But like any blended refrigerant, it must be charged as a liquid. Did you do that?

FYI liquid propane at 400 PSI and 150f+ will dissolve all sorts of things MEK will not touch.
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JohnHere
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Re: 1988 corvette, don't understand what it's doing?

Postby JohnHere » Sat May 16, 2020 9:31 am

In addition to everything already mentioned, are you sure that you installed the OT facing the right way?
tourmax
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Re: 1988 corvette, don't understand what it's doing?

Postby tourmax » Sat May 16, 2020 12:08 pm

JohnHere wrote:In addition to everything already mentioned, are you sure that you installed the OT facing the right way?


yep. Just had it out again to confirm.

The replacement orifice seemed to pass less air than the original when I tried to blow through it. So I cleaned the original and reinstalled it to see if it makes a difference. I can see less flow creating cooling issues, but it wasn't blocked. I would think if it is passing any refrigerant it would at least give some cooling. Might not be much, but right now I'm getting absolutely no cooling at all.

Pulling it down for a couple hours right now and I'll give it a try gain.

Should it not work, I'll pull the condenser out and see what I can see.....
tourmax
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Re: 1988 corvette, don't understand what it's doing?

Postby tourmax » Sat May 16, 2020 12:59 pm

well, I thought I had it.

Charged the system and as soon as the compressor started running, the low line went instant cold. I thought I had it with the orifice tube.

But no, it didn't last. It ran cold for a few seconds, even started getting condensate on the line, then.......nothing.

Went warm and never came back.

40 psi low and was originally 150-200 high. Then it went to 250, then 300 and topped out at almost 400 again while at 1500 rpm.

My limited knowledge keeps bringing me back to a clog on the high side somewhere.

Nothing left but pull the condenser I guess......
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JohnHere
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Re: 1988 corvette, don't understand what it's doing?

Postby JohnHere » Sat May 16, 2020 2:38 pm

Might be a combination of a clogged condenser and a bad accumulator, possibly with loose desiccant beads floating around inside.

As someone else mentioned, if you're seeing +/–400 PSI on the high side, the compressor is doing its job. With those kinds of pressures, don't forget to wear your PPE when working on this—especially a good pair of safety glasses and gloves.
tourmax
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Re: 1988 corvette, don't understand what it's doing?

Postby tourmax » Sat May 16, 2020 2:50 pm

JohnHere wrote:Might be a combination of a clogged condenser and a bad accumulator, possibly with loose desiccant beads floating around inside.

As someone else mentioned, if you're seeing +/–400 PSI on the high side, the compressor is doing its job. With those kinds of pressures, don't forget to wear your PPE when working on this—especially a good pair of safety glasses and gloves.


I wear a face shield.more convenient than safety glasses, more comfortable and more coverage.

Accumulator is orderd and on it's way. Fedex says should be here Thursday :roll: .

Condenser are quite expensive and for some reason, 88 seems to be a unique year for Corvette condensers. Most places list it as a one year thing (89 also seems to be a one year deal) and prices are around 400-500 bucks. That's USD. CAD would be somewhere around 700-800 (exchange, shipping, taxes, duties, etc).

I do know that 90+ they were "laid back" and 87 earlier I don't know what the difference would be. Perhaps it's because 87 and earlier uses the big round compressor instead of the Sanden type one.

It's definitely the 6mm piccolo type. At the prices I would have to pay for one, trying to flush the current one is at least worth an attempt. I've seen several references to it being "flushable", but I'm skeptical about the results after getting a good look at it's construction....
Dougflas
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Re: 1988 corvette, don't understand what it's doing?

Postby Dougflas » Sat May 16, 2020 3:38 pm

I personally think you're wasting your time trying to flush that condenser. Corvettes were know for having lousy AC systems to start with. To bring the high side down, mist the condenser with a water hose. If the high side drops like a rock, you have possibly an air flow problem and you're not rejecting heat.

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