AC not working

Tiny
IANMCDCA
  • MEMBER
  • 2006 CHEVROLET IMPALA
  • 3.5L
  • V6
  • 2WD
  • AUTOMATIC
  • 260,000 MILES
So I own several GM cars and vans that I run as taxis. I have been repairing them myself for eleven years. I have never come across this issue. This is a Canadian Impala with 48,5000 kilometers on it.

I have replaced the compressor twice (failed units) as well as the condenser and expansion valve. The system has been flushed. Orifice replaced. Still not cold inside and no sweating either on the lines or dripping from the car. Pressures on an eighty degree day are approximately 35-40 low and 150-180 high side at 1500 rpm. The blend door works: no hot air and lots of flow. I added approximately 1.2 oz of oil as that is what I lost in the replacement. Also added app. 1.6 lbs of aftermarket 134 equivalent The question: is it possible that a dirt filled evaporator would allow air flow but because the whole system to run warmer than it should? I am really stumped. Thanks in advance.
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Thursday, July 6th, 2017 AT 4:03 AM

24 Replies

Tiny
HMAC300
  • EXPERT
Amount should be 1.35 lbs so maybe over full? I assume it is been evacuated as well prior to a refill if anything would be blocked would be the orifice and screen.
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Thursday, July 6th, 2017 AT 6:35 AM
Tiny
IANMCDCA
  • MEMBER
Thanks for the reply. New orifice screen already. And yes, I'll refill to that spec but it has not for the second season dripped from the EVAP case but the hole is not plugged. And never any condensation on the lines under hood. All my other vehicles sweat from those lines. When I flushed the system, everything flowed well and again, the gauges do not imply a blockage.
Thanks again !
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Thursday, July 6th, 2017 AT 6:44 AM
Tiny
WRENCHTECH
  • EXPERT
If you grab the suction pipe where it comes our of the firewall, is it ice cold?

If you touch the liquid line after the condenser, what is the temperature? Is it ambient temp, warm to the touch or hot to the touch?

What happens to the pressures and temp if you bring the RPMs up to 3000?
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Thursday, July 6th, 2017 AT 9:18 AM
Tiny
IANMCDCA
  • MEMBER
So here is the scoop. I evacuated and refilled the system to correct weight. Ambient temperature is 85. At 1500 rpm, High side is 150-175. Low side is 32-38. At 3000 rpm, high side is 150-195. Low side 28-36. Suction at firewall is slightly cool. Liquid line is too hot to touch off the condenser.
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Thursday, July 6th, 2017 AT 2:28 PM
Tiny
WRENCHTECH
  • EXPERT
If your liquid line is too hot to touch, that indicates the condenser is not doing its job for one reason or another.
Try this. With the AC on high, get a garden hose and start spraying down the condenser and see if the suction pipe and the vent temperature get colder.
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Thursday, July 6th, 2017 AT 2:32 PM
Tiny
IANMCDCA
  • MEMBER
I will try that. Fans come on but not high speed and they are not always running. On a day like today I think they should be.

Thanks for the quick reply! Just to be clear: the liquid line off the condenser is the smaller one correct?
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Thursday, July 6th, 2017 AT 2:35 PM
Tiny
WRENCHTECH
  • EXPERT
The pressures are not high enough to trigger high fan which is surprising. There could be a number of reasons for that. You could have a bypass type condenser that can be 75% plugged up and still not raise the pressures. You could also have a service port that is positioned on the far side of a blockage so it is unable to see the high pressure.

There is something else not right here.
You stated you replaced both the expansion valve and the orifice tube. That is impossible. The system cannot have both. All the information I see shows this as an expansion valve system so assuming that is true, if you also installed an orifice tube also, remove it right away.
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Thursday, July 6th, 2017 AT 2:47 PM
Tiny
IANMCDCA
  • MEMBER
What GM calls an orifice on this car is just a screen. It is not the same as the older system.
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Thursday, July 6th, 2017 AT 3:04 PM
Tiny
WRENCHTECH
  • EXPERT
The term "orifice" means small hole. You cannot have that before the expansion valve. They both do the same job.
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Thursday, July 6th, 2017 AT 3:26 PM
Tiny
HMAC300
  • EXPERT
Check condenser for two things if there is a "bug screen " rip that off and throw it it cuts air supply down at least 15% then see if condenser is full of stuff. You might because of temperature put a fan in front of car and see if that changes things as well.
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Thursday, July 6th, 2017 AT 3:33 PM
Tiny
IANMCDCA
  • MEMBER
Wrenchtech. I am sorry. It must be my terminology. Yes. It has an expansion valve not an orifice. Alldata calls it an orifice tube. The screen fits into the tube in the second picture.
HMAC300. The condenser was replaced. The old one was aged. All pushed in from stones etc. The reason I changed it was that it seamed like that was my problem.
Spraying water on the condenser does not significantly change the vent temperature or lines.
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Thursday, July 6th, 2017 AT 4:07 PM
Tiny
WRENCHTECH
  • EXPERT
Is the pipe temperature the same at both ends of that tube?
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Thursday, July 6th, 2017 AT 4:34 PM
Tiny
IANMCDCA
  • MEMBER
Off the condenser into the evaporator? I will check. Do you think there could be too much oil? I have had the car three years. I replaced compressor with a used one. I flushed the system (only what I am supposed to). I am wondering if I did not get all the original oil out?
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Thursday, July 6th, 2017 AT 4:37 PM
Tiny
WRENCHTECH
  • EXPERT
You put less than 2 oz of oil. That should not be the problem. Was the condenser replaced before or after the last compressor replacement?
Did you add oil to the compressor itself? Where in the compressor?
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Thursday, July 6th, 2017 AT 4:42 PM
Tiny
HMAC300
  • EXPERT
One other thing if this has an expansion valve does it work? Is the piece that tells it to open/close making good contact with evaporator? And insulated or does it stick into coil and fell out or came out. Check that as well.
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Thursday, July 6th, 2017 AT 4:43 PM
Tiny
IANMCDCA
  • MEMBER
Wrenchtech. Condenser was replaced after the compressor. Added oil to both sides meaning just the top. Not the drain plug in the bottom.
HMAC300. The expansion valve is brand new. It does not stick into evaporator.
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Thursday, July 6th, 2017 AT 4:59 PM
Tiny
IANMCDCA
  • MEMBER
And to be clear, the system has not blown cold since the first compressor change two years ago. The system was flushed at that point.
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Thursday, July 6th, 2017 AT 5:01 PM
Tiny
WRENCHTECH
  • EXPERT
That plug is the crankcase and that is where all oil has to be added.
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Thursday, July 6th, 2017 AT 5:03 PM
Tiny
IANMCDCA
  • MEMBER
Hmmmm. Not what I was told but makes sense. It was never drained before I put it in. So then maybe I added too much oil?
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Thursday, July 6th, 2017 AT 5:06 PM
Tiny
IANMCDCA
  • MEMBER
So after starting over, I realized that the fans will not come on when the AC compressor is engaged. My other 06 fans stay on constant when the compressor engages. It's gauge readings never move whether at idle, 1500 or 3000 rpm.
They come on every 40 seconds to bring down the engine temp but that's it.
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Saturday, July 8th, 2017 AT 2:21 PM

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