Over hauling AC in 1995 Corvette

[case2001]

Hi,
Just an update. I have all the components for the system. I am disassembling the system on the car.

The new Denso compressor was shipped with 7.8 oz of PAG 46. According to the way I read the manual and from the above thread the entire system requires 8oz of oil.

Should I drain half of the oil from the compressor and place remaining amount plus 0.2 oz in dryer? Or should I distribute the 4oz between the dryer, compressor and evaporator.

Thanks again!

[JohnHere]

If all 8 ounces will fit in the compressor, you can put it there without issues as long as you rotate the main-shaft by hand about a dozen times, using a wrench if needed.

If you prefer to oil-balance, place 3/4 ounce in both the condenser and evaporator, 1/2 ounce in the R/D, and the rest in the compressor, rotating the main-shaft as before.

[case2001]

Thanks.

I’ll add the 0.2 to the compressor and once installed will rotate the compressor as suggested. Thanks!

[tbirdtbird]

Sure looks like spam to me

[case2001]

We finally completed everything today. Installed all the new components. Nitrogen tested the system for 2 days no leaks. Pulled the micron gauge down to 670.

Put in the 32 oz of Freon 134. Ambient temp 80 degrees humidity 61%. With full cold, blower on high, doors open and engine at 1500 RPM. High side 150 low side 45. Temp out of center vent full cold 45 to 48 degrees.

Don’t know if it will work tomorrow or if we missed anything. But I will keep you guys posted.

Anything else I should do or know?

Thanks for the help!

[case2001]

We finally completed everything today. Installed all the new components. Nitrogen tested the system for 2 days no leaks. Pulled the micron gauge down to 670.

Put in the 32 oz of Freon 134. Ambient temp 80 degrees humidity 61%. With full cold, blower on high, doors open and engine at 1500 RPM. High side 150 low side 45. Temp out of center vent full cold 45 to 48 degrees.

Don’t know if it will work tomorrow or if we missed anything. But I will keep you guys posted.

Anything else I should do or know?

Thanks for the help!

Whoops rookie mistake. I was looking at Temp scale on my gauges when I wrote the above. The psi on the low side was 35 and high side was 250 to 260. Is my high side too high. The car of course was running almost an hour. I went slow with the Freon.

Thanks again

[JohnHere]

The psi on the low side was 35 and high side was 250 to 260. Is my high side too high.

Even though it's a Corvette, which isn't known for an efficient A/C system, the pressures are a little higher than I'd like to see at an ambient of only 80°F, especially the high side. What kind of fan do you have in front of the engine, and how old is it?

A low side of 35 PSI correlates to an evaporator temperature of about 41°F, which helps explain why your center vent temperatures are only moderately cool.

[case2001]

Thank you for the reply.

This year model has 2 small fans. I think they are each 12 inches. The both turn on medium when the AC is on. I believe them to be original so they are probably tired.

I went for a drive yesterday ambient was 82 and center vent was 41 degrees Fahrenheit. The low pressure lines were loaded with condensation.

I carefully weighed my charge. I am certain my son and I only put 2 pounds of Freon 134. The expansion valve is the stock GM.

This has been a great learning experience for us. Thanks again for everyone’s help.

[case2001]

I checked the static pressures and compared the gauges temperature readings. The pressure was equal on both high and low sides and was correct with the ambient temperature.

I noticed on my cheap gauges the 0 is a range on both high and low sides of about 5 on the low gauge and 10 to 15 estimated on the high. So I think the pressures I had would be +- 5 on low side and +- 15 on high.

However, the bad news is when I removed the low pressure service port there was a momentary wisp sound. So I believe the brand new low pressure line’s Schrader valve may have leak! Do you think I should try to tighten it? I don’t have the valve core removal tool and have never used one. Would you recommend replacing the valve?

Thanks.

[JohnHere]

I noticed on my cheap gauges the 0 is a range on both high and low sides of about 5 on the low gauge and 10 to 15 estimated on the high. So I think the pressures I had would be +- 5 on low side and +- 15 on high.

Okay. I would still consider replacing the fans. A Corvette can benefit from all the condensing it can get, and a set of new fans will help with that.

However, the bad news is when I removed the low pressure service port there was a momentary wisp sound. So I believe the brand new low pressure line’s Schrader valve may have leak! Do you think I should try to tighten it? I don’t have the valve core removal tool and have never used one. Would you recommend replacing the valve?

The Schrader valve probably meets GM specs since it's new, but you could replace it if you have any doubts. It's an inexpensive, simple job. The service-port caps are considered the primary seal, though, so look inside each of them to ensure the o-rings are there, lubricate them with a little PAG oil or Nylog Blue, and don't forget to replace both caps when you're done servicing the system.