A/C help....2004 Chevy Tahoe.

LIGHTNING LARRY

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I just bought a 2004 Chevy Tahoe. Fully loaded. Got a smoking ridiculous deal. Guy was hurting for money.

BUT! The A/C doesn't work. Evacuated it to -30 lbs then added Freon from a 30lb bottle. Compressor kicked on and it started blowing cold.

As soon as it got to about 35lbs pressure low side on my gauges it quit blowing cold. Pressure went up to about 100lbs.

Bled it back down to about 30lbs. Compressor is working but not blowing cold front or rear .:mj:

Now, here is a strange thing I've never seen. The low press and high press connections are on the same hose. WTF?

HELP. It's too ****ing hot here not to have A/C
 

BDF8

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Sounds like something got clogged in the main line and you got back pressure. Did you have any Freon evacuate?
 

BDF8

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When it jumped to 100, did the pressure relief pop?

I would also check to make sure the fan that pulls air through the condenser is working as well.
 
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Thump_rrr

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Ok let me get this right.
When you bought the truck was there any refrigerant in the system?
If yes was the gas recovered to figure out if the proper amount was in the system?
The system was vacuumed to 30"HG (-15psi or 30"HG is total vacuum)
Then the system was charged.
Was the charge scaled in with the cylinder on an electronic scale to ensure the proper charge was put in the system?

When the compressor cut out it is normal for the pressure to go to 100psi since ambient temp must have been around 88F.

It is normal for the compressor to cut out at around 35psi to avoid freezing the evaporator.

The question is what was the high side pressure?
Was the condenser fan running?

Edit I just saw that the 2 connections are on the same hose.
There must be another connection somewhere for the high side.
 
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BDF8

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NO. No pop. The compressor still kicks on when you turn on the a/c. Only has the engine fan.


Two things.

1. When there is a sudden surge it usually means air got into the system and caused back pressure. Common occurrence and completely voiding the system and recharging 9/10 does the trick.

2. I'm gonna have to do a little research on your Highs and Lows because I have never seen them on the same line. Do number one and report back.

Also, Not trying to beat a dead horse but that Condenser fan is more important then you would think


Good Luck Larry!
 
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Thump_rrr

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Typically the high side fitting is at the outlet of the condenser before the orifice tube(s).
If you have rear a/c there should be a Y block splitting the liquid line going to the 2 orifice tubes.
The low side fitting is usually on or near the accumulator reservoir which is going back to the compressor.
The high and low side connections are different sizes so that they cannot be mixed up with the low side (suction) being blue and the high side (discharge) being red.
 

Thump_rrr

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NO. No pop. The compressor still kicks on when you turn on the a/c. Only has the engine fan.

When you say it only has the engine fan you mean that the truck has no electric fan but only a belt driven fan?
If so does the engine can sound like the hydrostatic clutch is working?
 

derklug

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GM puts the low side and high side ports on the same line, the fixed orifice is between them.
Was the compressor still running when the pressure shot up to 100?
What was the high side pressure reading?
Do you have a scan tool available?
 

Way2QWK

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high and low side service ports on the same line are typical of many GM products....that just means the orifice tube is located in between the two ports. The line comes apart and the orifice tube can be pulled out.
 

LIGHTNING LARRY

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Typically the high side fitting is at the outlet of the condenser before the orifice tube(s).
If you have rear a/c there should be a Y block splitting the liquid line going to the 2 orifice tubes.
The low side fitting is usually on or near the accumulator reservoir which is going back to the compressor.
The high and low side connections are different sizes so that they cannot be mixed up with the low side (suction) being blue and the high side (discharge) being red.

I understand this. That's why I'm confused about both fittings being on the same hose.
 

99cobrablack

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Just fought this same problem with a plugged orfice tube on a peterbilt. Pressures nearing the same as yours. Except it worked until parked, but it's got Black Death in the lines now. Could you have possibly slogged it with liquid refrigerant if you don't have an orfice problem?
 
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