Engine Size: 3.5
Refrigerant Type: 134a
Ambient Temp: 90
Pressure Low: 60
Pressure High: 165
Country of Origin: United States
My wives 01' Aurora A/C is not cooling. On a 90 degree day, the temperature at the vents is about 70 degrees at idle with the fan on high. When I'm on the interstate, I can get about 55 degrees with the fan on high. This car has two cooling fans and both are working and spinning fast. When I hook up my gauges, I'm showing the following:
700 - 800 RPM's, fan on high, low side 59psi, high side 165 psi.
700 - 800 rpm's, fan on low, low side 38 psi, high side 150 (needle was jumping around on high side gauge)
1500 RPM's , fan on low, low side 35 psi, high side 165 psi.
1500 RPM's, fan on high, low side 54 psi, high side 230 psi.
I had my dads mechanic pull all the freon out of the system, evacuate the system down to 29 mercury for 30 minutes, left system in a vacuum for another 20 minutes to check for leaks. We filled the system back up with exactly 2.0 LBS of r-134a. This did not help. Still not cooling. The low side readings are now higher at idle with fan on high, around 60 psi or higher
He suggested that maybe the variable control valve on the compressor was bad, but I don't think this compressor has one. The AC /Delco part number is 15-20752.
So the other thing about this car is it has an electronic orfice valve. I don't know if it's called an expansion valve, but it's electric and when I unplug it, i can see an increase of about 5 pounds on the low side, so it appears it's working.
My question is how do I know if the compressor is bad or if the orfice valve is letting to much refrigerant through (stuck open), which would result in a high low side pressure?
One other thing to mention is on my other car , where the AC works great, when I hook up the gauges and hit the gas, the low side pressure drops quickly. On the Aurora, no matter how much I rev the engine, i cannot get the low side to drop. I never cycles on and off.
Any suggestions would be great.
Edited: Wed June 24, 2009 at 10:56 PM by slantdawg
So I was thinking that before I replace the compressor, I would open the system to check the expansion valve to see if there is a block or metal shavings. I would think though that a blockage at the expansion valve would cause a very low2 pressure on the low side and a high pressure on the high side???
I have a listing of 35 ounces of R134a. A few ounces can make a big difference in performance.
thanks TRB. The mechanics book also said 35 ounces, but there was a sticker under the hood that said 2.0LBS, so we figured that would be more accurate.
If I add more refrigerant, do you think it would raise the low side pressure even more?
What doesn't seem right to me is that I can never get the low side to come down in pressure, even if I raise the idle and run water across the condenser. Do you know what else besides a weak compressor would cause this condition? I don't mind replacing the compressor, but I wanted to make sure that was the issue.
This is what I'm thinking and if someone disagrees, please let me know:
1. Since my high side pressure is not really that high, I think there is no blockage in the condenser or orifice valve.
2. Since my low side pressure is kind of high, maybe the compressor is not sucking/pumping like it should.
3. With the low side pressure kind of on the high, if it's not the compressor, could it be my orifice valve is open more then it should be, allowing more refrigerant over to the low side then it is suppose to? It's actually an electronic expansion valve, but I keep hearing it called an orifice valve. I know what a orifice valve normally looks like (you can't see it because it is inside the system) but this is basically a solenoid that cuts on and off at different pressures between the high and low side. Could this be allowing to much refrigerant through to the low side? Does anyone know of a procedure to check the expansion valve?
Edited: Fri June 26, 2009 at 7:37 AM by slantdawg
It could be a weak compressor but I would get the proper charge level in the system before making that call. This does have an electric orifice valve on it so that would be an area to look at also. I have not checked but you might be able to use an ohm meter to check it's operation. GM Tech might be able to add something on these orifice devices.
Thanks TRB. One thing I wanted to add is if i unplug the orifice valve, I immediately see an increase of pressure on the low side of about 5 psi. If I plug it back in, I loose 5 PSI. This tells me that is works, but I wonder if when the valve is closing, if it is closing the full amount it should. That I think will be the hard thing to test but if anyone knows a way, I would be grateful.
I guess there is no way to know how much oil is in the system?
I'll probably open the expansion valve and first look for foreign material. Then while the system is open, replace the accumulator and maybe drain the oil and then replace the oil. Also will flush the system out if necessary and then evacuate the system
Anyone know the proper amount of oil and oil type and weight for this car?
9 oz of PAG 150 and 35 oz R134a
so I brought the car into a mechanic today and he said the compressor is bad. He said he is gettig 70 - 80 on the low side. He said the compressor is pumping, but low side valve is bad, so when it compresses to the high side, some if it is actually pumping back into the low side. I gues a new compressor it is!
I was wondering if anyone has ever experienced this?.. I went to the auto parts store to buy PAG oil. Looked in the book just to be sure and it says for a 01' -03' Aurora it needs PAG46, but other people in this forum say PAG150. The book was by Intermediate (I think is the brand) ..not sure what to use..Anyone know for sure?
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