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charging ac system 134a

turbochargedv8 on Fri July 24, 2009 8:43 PM User is offline

Year: 1992
Make: cadillac
Model: sts
Engine Size: 4.9l
Refrigerant Type: 134a
Pressure Low: 65
Pressure High: 185
Country of Origin: United States

This system appears to have been converted to 134a. There was a hole in the low side line that i got repaired. Im attempting to charge the system and added about 33oz of 134a. The ac never blew cold and never really worked well. It seems to blow somewhat cool but not cool enough. I replaced the accumulator, the low side lines near the accumulator and evap are cold but it don't blow cold air.

could it be the trap doors not functioning properly

Chick on Fri July 24, 2009 9:53 PM User is offlineView users profile

Did you pull a deep vacuum and charge into the vacuum? what was the outside temp when you took those pressures??

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

turbochargedv8 on Fri July 24, 2009 10:06 PM User is offline

Yes i vaccuumed the system for 45 minutes and it held for over 5 minutes before i charged. I even bleed out the lines on the guages before i opened the gauge valves. outside temp was about 90

Chick on Fri July 24, 2009 10:29 PM User is offlineView users profile

You appear to be a little undercharged then, I would feel the lines going into and out of the evap, should be the same temp, outlet just slightly colder..If they are not, then add an ounce or two at a time and wait for the system to adjust while watching the pressures. at 90 degree ambient you can go as high as 225 to 250 safely..even more if necessary..but just go slowly...The return line to the compressor (suction line) should be very cold, just like after the O tube...

Also check to see that hot air is not mixing with the cold air from the evap, by either the heater core hot air mising with the cold, , or blend door problems..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Edited: Fri July 24, 2009 at 10:34 PM by Chick

turbochargedv8 on Fri July 24, 2009 10:49 PM User is offline

Im going to check into the air mix by the evaperator
i think hot air might be mixing in

turbochargedv8 on Sat July 25, 2009 3:13 PM User is offline

just checked trap door and it doesnt appear to be the problem. This time the instrument panel read ac over heated then the ac compressor shut off to protect itself.

could the ac overheating and not cooling be a result of a orfice tube? we never changed it. Do we need more oil in the system we never added any either.

turbochargedv8 on Sun July 26, 2009 5:12 PM User is offline

I noticed when i went to charge it up there was always a little freon left in the can. Is this normal when using the 12oz cans to charge your system.

My next plan is to replace the orfice tube and add some oil in the system and see if that helps.

my compressor is good if i was able to get a reading on my guages right?

Chick on Sun July 26, 2009 9:48 PM User is offlineView users profile

Check the O tube for debris, and yes, you need to add oil back, let us know what the O tube looks like and we'll go from there...

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

turbochargedv8 on Tue July 28, 2009 7:54 PM User is offline

just pulled O tube and its clogged with metal particles
most looks like gray clay and shiney metal particles
the screen looks collasped on one side

HECAT on Wed July 29, 2009 7:15 AM User is offline

Quote
Originally posted by: turbochargedv8
could the ac overheating and not cooling be a result of a orifice tube? we never changed it. Do we need more oil in the system we never added any either.[/qt]

The OT contains compressor wear parts. The gray clay is powdered metal and oil. Depending on the condenser design, this may be a sign of most of the debris (tube & fin cond) or that most of it lies at the inlet of the condenser (serpentine or parallel cond) and could not pass.

No info on how the conversion was done makes me concerned about the oil type, quantity and quality; maybe time for a good flush, a new compressor, and start with fresh oil.

At minimum, I would replace the OT and add back for oil lost from the hose failure and accumulator replacement.



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GM Tech on Wed July 29, 2009 8:55 AM User is offline

That OT is terribly dry- looks like compressor is worn out (or nearly worn out) from running low on refrigerant (and oil).

On a normal system- that OT would be soaked with oil......

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

daman on Wed July 29, 2009 9:05 AM User is offlineView users profile

Quote
Originally posted by: turbochargedv8
I noticed when i went to charge it up there was always a little freon left in the can. Is this normal when using the 12oz cans to charge your system.

I dip my cans in warm to hot water a few times wile charging, helps force that last little bit of freon out of the can.

and like GM tech said looks dry/low on oil..



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turbochargedv8 on Wed July 29, 2009 4:55 PM User is offline

My plan is to replace the compresser, condenser, O tube, and add the correct oil. What type of oil should i use for a system thats been converted to 134a? Is there a way to flush out other various parts such as the evaperator without the flush type machine? I have a air compresser with a blow tip.

HVargas on Wed July 29, 2009 5:58 PM User is offlineView users profile

I would recommend using our BVA Auto 100 with your system. You can also flush the lines and evap. out with one of our kits. You can buy Hecat 1/2 Gallon flush here and the gun to flush it as well. Mastercool A/C Flush Kit You will want to replace the drier as well and then charge it with about 80% of the R12 capacity.

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