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Over/Undercharged?

JW on Fri July 30, 2010 9:33 AM User is offline

Year: 1995
Make: Chevrolet
Model: Lumina
Engine Size: 3.1L
Refrigerant Type: R-134A
Ambient Temp: 91
Country of Origin: United States

Hello all:

Recent new compressor, accumulator, orifice tube (old one was clean). Vacuum held and charged with approx. 2.8 12oz cans r-134a (supposed to be 2.0 lbs or 32 oz). Here is what I am getting:

Temp: 91
Humidity: 60%
Static: 117L/112H

AC on max with fan on high (#4), windows down, doors closed:

Idle 44L / 205H / 60 degrees
At 1500rpm 39L / 232H / 58 degrees

Other fan speeds at 1500 rpm

#3 34L / 225H / 53 degrees
#2 31L / 212H / 49 degrees
#1 27L / 190-250H / 43 degrees (second radiator fan turns on at 250 psi)

Hoses and accumulator are sweating, and with fan on high, there is almost a steady stream of water running out of the evaporator tube.

Car does take a while to cool down. Is there anything above that could point to an undercharge or overcharge condition? Something else I am missing? Thanks


JW on Wed August 04, 2010 5:55 PM User is offline

72 views and no responses. Am I not asking the right question, not enough information, or just a non-intelligent question? Just wondering. Thanks in advance for any help.

NightOwl on Wed August 04, 2010 6:28 PM User is offline

Hi JW:

If you can get a hold of or at least look at a shop manual that should give you the general range of operating pressures on a system operating at "optimum."

I hope you remembered to add oil for each item replaced. There should be a table of the amounts for each item replaced also in the shop manual. If you didn't add oil then or if you didn't use 134a "first" charge kit at a minimum I wouldn't run it until you get it evacuated again and get the oil in other wise you'll lose all your hard work to compressor failure for lack of lubrication.



I hope this helps.


Sincerely, NightOwl



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Courage is not the absence of fear. Courage is being afraid and doing your duty anyway.

TRB on Wed August 04, 2010 6:30 PM User is offlineView users profile

Compressor Type Harrison V5 5-Cyl. Or HD6/HR6-HE 6-Cyl.
System Oil Capacity 8 ozs.
Refrigerant (R-134a) Capacity 32 ozs.
System Operating Pressures (3)
High Side 275 psi (19.3 kg/cm2 )
Low Side 37 psi (2.6 kg/cm2 )

Approximate maximum operating pressures with ambient temperature of 70°F (21°C), relative humidity of 50 percent, and engine speed of 2000 RPM.



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1stbscout on Wed August 04, 2010 6:46 PM User is offlineView users profile

The high side looks to be slightly low and the low slightly high at MAX. Seems odd to see the other numbers being what they are as well.
How long did you let the system stabilize before checking pressures and duct temp on all 4 settings.

Normally at the lowest fan setting you will have the lowest low side AND the lowest high side. Your chart shows it to have the highest high side?!?!

If you are reasonable sure that you have installed the amount of R134 you think you have there are for sure other issues. What are temps at the inlet and outlet of both the condenser and evaporator?

Does the compressor cycle at the low fan setting?
Was the system flushed and why were the parts changed?

There is no set value for the high and low pressures. They vary with the ambient and load on the system. Also with the efficiency of the parts installed which are never exactly the same.

Cussboy on Wed August 04, 2010 8:08 PM User is offline

And make sure that the heater is not contributing any heated air to the mix. The plenty-dripping evaporator means it's cooling below the dew point of the air, so good.

Edited: Wed August 04, 2010 at 8:09 PM by Cussboy

Chick on Wed August 04, 2010 10:58 PM User is offlineView users profile

Obviously very humid if the drain is dumping water, check the inlet and outlet of the evap, should be the same temp, with the outlet (suction) slightly cooler, if it is, your system is full and you're working against a hot and humid day, take it for a ride, the temps will drop, lower fan settings once the car is comfortable will also drop the vent temps..Remember it's not a refrigerator, and you have to fight the solar rays that keep heating the inside, you want to remove the humidity mostly.. Drive it when the sun goes down too, should see a big difference...

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Chick
Email: Chick

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