A/C cycle issue
Thread Starter
Drifting
Joined: Oct 1999
Posts: 1,722
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From: Gloucester Va
A/C cycle issue
I had the A/C working fine years ago. Long story short took it off, and have decided to put it back on. Pull a vac., and all that good stuff. The compress. cycles on then off about 5-10 sec. for each. I've managed to get about 2.75 cans of R134A in it. Yes, I had it working just fine with R134 before. It's an 88 vette with electronic a/c.
Racer
Joined: Nov 2006
Posts: 301
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From: Ft. Worth Texas
What is your outside temp. and what pres. are you seeing on the manifold.
High and low side. Sounds like you are under charged. With R-134 you only need about 85% of what the mfg. states
Steve
High and low side. Sounds like you are under charged. With R-134 you only need about 85% of what the mfg. states
Steve
Last edited by Bulldog Steve; Aug 12, 2007 at 12:29 PM.
Safety Car
Joined: Jul 2004
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Racer
Joined: Nov 2006
Posts: 301
Likes: 0
From: Ft. Worth Texas
Your system should hold 44.0 oz. of (R-12) and 8 oz oil since you have gone over to R-134 i would start out with about 85% of 44 oz. and watch your pressure on your manifold high and low side. Rule of thumb high side pressure should be approx. 2.2 x the outside temp about 2 inches in front of your condenser. Also do you have a fan clutch it could be weak not drawing enough air across the condenser....
Steve
Steve
Racer
Joined: Nov 2006
Posts: 301
Likes: 0
From: Ft. Worth Texas
If all you did was replace the drier and o tube and added 3 oz. of oil and pulled into a deep vac. and it held you should be ok. Your system holds 44.0 oz. of r-12. 85% of 44 oz is 37.4 oz of R-134 ( 3 12oz cans) that should have been added to begin with. If you where near here i would come to help you.........
Dont give up thats what we are here for to help each other.
Steve
Dont give up thats what we are here for to help each other.
Steve
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Safety Car
Joined: Jul 2004
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some additional info ya might want to read about;
http://forums.corvetteforum.com/show...post1561487190
http://forums.corvetteforum.com/show...post1561487190
Safety Car
Joined: Jul 2004
Posts: 3,835
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Thank you all for the help. I'm going to give this deal one last try. I'll take the car to work tomorrow and pull the freon out, and pull the system apart. Check out the O tube and check for signs of metal. Then check to see if i can figure out how much oil is in the system. I'll post my findings after. Most likely followed by questions. 
Safety Car
Joined: Jul 2004
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Safety Car
Joined: Jul 2004
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I can only laugh at this point, and please join in. I pulled the system apart and found... That in a moment of wisdom, or lack thereof, I put the O tube in up side down. 
Now I know why that thing was so hard to get in.
Even harder to get out. I was scared for a min. I may not get it out. When the top (aka bottom) plastic part broke off leaving the metal tube and lower (aka upper 1/2 as you know it) stuck. I'm not sure what kind of problems this could cause? I did find very fine metal on the tube. I poured the oil out of the compress. and it was clear. Looked good. I got about 6 OZ out of the compress. The dryer, however had about 2 oz of oil and that was a nice silver color. I liked the color, but not what it means.
Safety Car
Joined: Jul 2004
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......the "O"-tube is a metering device and the reason your evaporator gets cold is because you are taking a high(er) pressure and sending it through the "o" tube. since the diameter of the evaporator "pipes" are larger, a pressure drop will ocurr and this causes cold.....the pieces and every bit of it has to come out!.....over time, they WILL find their way into the compressor and take that out, PERMANENTLY...
Last edited by Da Mail Man; Aug 15, 2007 at 08:50 PM.
Safety Car
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Luckly I got the "O" tube out. It pretty much broke in half and I got both pieces out just fine. No left over pieces in the tube. I will flush the system out once more, and try again. I will also replace the "O" tube, and dryer. Anything I'm missing?
I used Ester oil this last time. Can I change over to Pag oil? Will the pag oil cause problems with the ester oil left over in the compress.?
I used Ester oil this last time. Can I change over to Pag oil? Will the pag oil cause problems with the ester oil left over in the compress.?
.....also, what refrigerant are you using?...that determines what oil you have to use!....you CANNOT just switch oils merely because you want to!...
....different refrigerants require different and SPECIFIC oils!......if you use the wrong oil, the ENTIRE system has to be flushed and compressor drained to remove all the "foriegn - incorrect" oil...
...i don't know how you are putting in any of the refrigerant - if using gauges or what nor do i know if you are monitoring BOTH ports on the system with same...
....you also do realize that if you have a refrigerant source connected to the gauges and you open the wrong valve, the can could very well explode causing VERY serious injuries to include blowing your hand off and even death, right?....