Need expert help on 1985 Corvette ac overhaul

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agillings
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Joined: Tue Jun 08, 2021 5:37 pm

Need expert help on 1985 Corvette ac overhaul

Post by agillings »

Need some Help. What am I doing wrong? All work done IAW 1985 Corvette Shop Manual. I am just going to list the things and the way I did it. R12 System worked before rework.
Removed and replaced everything.
New Compressor R4
New Condenser stock ACDelco OEM
New Acum/Dryer OEM
New Evaporator OEM
All new Hoses OEM
New Orafice White
Installed orafice (long screen towards condenser) all OEM
New equipment/ hoses/Flushed, Dried and Vac. Blew shop air through all connections no blockage. Vac system with vac pump 3 hours and held for 12 hours

Installed Ester oil
3 oz in compressor,
2 ounces in Dryer,
1 ounce in condenser
1 ounce in evaporator
Charged
Used gages to fill from low side
High side valve closed
Filled 2 3/4 cans of R134a
Compressor started and cycles
Does not get cold on any vents or any lines getting cold just HOT.
Low pressure gage reads 80 psi and High side reads 150 psi. All lines are hot
Took system apart again and found:
No oil in Compressor
No oil in Dryer
No oil in Condenser
All oil in bottom of Evaporator

Repeated everything above. Ordered a new dryer will install and start again to fill.

Thanks for any input. My hair is getting gray! Art
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Last edited by agillings on Wed Jun 09, 2021 2:35 am, edited 1 time in total.
tbirdtbird
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Re: Need expert help on 1985 Corvette ac overhaul

Post by tbirdtbird »

More background...
which compressor is on there now?
Did you convert the R12 system to 134? I suspect you did if you used ester oil

Is there any location on the hi side hose that shows frost?
How did you determine which CCOT to use?
How long did you vacuum, shop air is wet air
Did you fill the compressor yourself? Best to dump out whatever it comes with and add correct oil charge yourself (so that you know for sure) then spin shaft about a dozen times to distribute the oil

You are obv not getting oil return, don't run it until this is fixed
agillings
Posts: 4
Joined: Tue Jun 08, 2021 5:37 pm

Re: Need expert help on 1985 Corvette ac overhaul

Post by agillings »

Thanks all your answers to your questions are answered above. its a rebuilt R4 compressor
tbirdtbird
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Joined: Sat May 02, 2020 1:48 pm

Re: Need expert help on 1985 Corvette ac overhaul

Post by tbirdtbird »

"Thanks all your answers to your questions are answered above. "

or not
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JohnHere
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Location: South Carolina Upstate - USA

Re: Need expert help on 1985 Corvette ac overhaul

Post by JohnHere »

agillings wrote: Tue Jun 08, 2021 5:42 pm Installed Ester oil
3 oz in compressor,
2 ounces in Dryer,
1 ounce in condenser
1 ounce in evaporator
Oil amount and distribution sound correct. Not that it won't work, but I'm curious why you decided on ester oil instead of PAG.
agillings wrote: Tue Jun 08, 2021 5:42 pm New equipment/ hoses/Flushed, Dried and Vac. Blew shop air through all connections no blockage. Vac system with vac pump 3 hours and held for 12 hours
Sounds good. If shop air introduced any moisture into the system, evacuation for three hours should have removed most or all of it.
agillings wrote: Tue Jun 08, 2021 5:42 pm Charged
Used gages to fill from low side
High side valve closed
Filled 2 3/4 cans of R134a
Compressor started and cycles
Does not get cold on any vents or any lines getting cold just HOT.
Low pressure gage reads 80 psi and High side reads 150 psi. All lines are hot
Took system apart again and found:
No oil in Compressor
No oil in Dryer
No oil in Condenser
All oil in bottom of Evaporator
Trusting that each small can of refrigerant contained a full 12 ounces, 2-3/4 cans equal only 33 ounces of R-134a. Since the original specs call for 52 ounces of R-12, I think that your charge amount of +/- 33 ounces is nearly 10 ounces low, a substantial shortfall. If that's the case, you should increase the charge weight to about 42 ounces or around 80-percent of the original R-12 amount.

I would recover what's in there now, recharge to 42 ounces, then see how it performs and what the pressures are. The increased amount of refrigerant should also fix the oil-return issue, unless there's a problem with the accumulator.

By the way, did you use a refrigerant scale to weigh-in the charge?

You mentioned that the accumulator was a new OEM unit. But does it contain R-134a-compatible desiccant? If not, that could be an issue. Also, were the ports sealed tightly when you received it? If not, the desiccant was probably saturated. Also, it's not unheard of for an insect to make its home inside, especially if the unit was setting uncapped for who-knows-how-long in a warehouse someplace.
agillings wrote: Tue Jun 08, 2021 5:42 pm New Orafice White
Installed orafice (long screen towards condenser) all OEM
The orifice tube sounds like the correct one, and your installation of same appears to be correct. So the OT doesn't seem to be a problem unless the orifice itself got plugged somehow. But the high low-pressure side doesn't reflect that.

While working on this, did you check for a re-heat problem--that is, the heater not turning off and introducing hot air into the evaporator plenum?
agillings
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Joined: Tue Jun 08, 2021 5:37 pm

Re: Need expert help on 1985 Corvette ac overhaul

Post by agillings »

Thank you for the responses. Anyway I did everything I listed above again and got 47 degrees a center vent. All pressures oil amoumt etc are in accordance with the 1985 Corvette shop manual. Thanks again
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JohnHere
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Location: South Carolina Upstate - USA

Re: Need expert help on 1985 Corvette ac overhaul

Post by JohnHere »

Corvettes aren't known for outstanding A/C performance, at least the front-engine models. I don't know about the 2020-on mid-engine cars. So IMHO, 47 degrees at the center vent on a hot day seems pretty good.
agillings
Posts: 4
Joined: Tue Jun 08, 2021 5:37 pm

Re: Need expert help on 1985 Corvette ac overhaul

Post by agillings »

I Vent temp dropped to 45 degrees vent temp. I guess I lucked out installing all new parts. Thanks again
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Tim
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Re: Need expert help on 1985 Corvette ac overhaul

Post by Tim »

Quality POE is a better option IMO for conversions. Some of the DEC PAG oils claim to work with both refrigerants and still mix with Mineral oil.
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