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2006 chevy trailblazer 4.2l from a 2004 trailblazer
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Discussion Starter · #1 ·
We got this trailblazer for free from my girlfriends father. he worked at a shop and swapped the engine from a 2004 trailblazer into our 2006 trailblazer. To do so had to disconnect the ac lines. a year later I decided to finally fix the AC, i got the vacuum, manifold gauges, 3 cans of 134a, and a can of oil all just incase. I hooked the vacuum up today ran it for an hour got down to 30 nice and good. turned it off left it for an hour and was still holding the vacuum, so no leaks that's a plus. Now onto my issue. I replaced the vacuum with a can of 134 purged the air and then attempted to fill it with ac on running full blast (also tried on low) the low side gauge is now sitting at 100 and not moving. the high side says below 0 on the vacuum still. the compressor just wont kick in. A buddy told me to jump the relay so I did. the clutch or whatever was spinning now but the gauges stayed the same. so end story still has hot air. What should i start with. if i have to i can do the compressor, drier, and orifice tube. Dont wanna break the bank on it all if i dont have to.
 

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2002 chevy trailblazer_lt
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My suspicion is that something is not properly setup with your manifold and gauges. If they were correctly setup there is about no way you could have 100 psi on the low side and zero or less on the high side.

Can you show us what you have?
 

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2006 chevy trailblazer 4.2l from a 2004 trailblazer
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Discussion Starter · #3 ·
My suspicion is that something is not properly setup with your manifold and gauges. If they were correctly setup there is about no way you could have 100 psi on the low side and zero or less on the high side.

Can you show us what you have?
I can set it back up tomorrow. I'm not to sure how they could be set up wrong. I may be reading it wrong though. But I'll post pics when it's day time again
 

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2006 chevy trailblazer 4.2l from a 2004 trailblazer
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Discussion Starter · #4 ·
So here is some pics it's still climbing. If you want I can upload a video to YouTube that shows a bit more
PXL_20210609_133437723.jpg
PXL_20210609_133445398.jpg
16232461719463411114711951826033.jpg
 

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2004 chevy trailblazer_ls
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The first picture looks like there's no freon in the A/C. Second one seems like the high pressure guage is ng. Are the schrader valves in the lines any good, and are you sure the high pressure guage is firmly hooked up? Make sure the compressor is coming on, look for the clutch spinning.
Since you jumped the switch on the accumulator, make sure the high pressure switch is good. A Tech2 or the phone app will tell you.
 

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2006 chevy trailblazer 4.2l from a 2004 trailblazer
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Discussion Starter · #6 ·
The first picture looks like there's no freon in the A/C. Second one seems like the high pressure guage is ng. Are the schrader valves in the lines any good, and are you sure the high pressure guage is firmly hooked up? Make sure the compressor is coming on, look for the clutch spinning.
Since you jumped the switch on the accumulator, make sure the high pressure switch is good. A Tech2 or the phone app will tell you.
Yes the 1st one was with a vacuum hooked up no freon. I'm not sure if the valves are any good. Got this vehicle for free and never had ac since the engine swap. The gauges are fully hooked up everything is tight. The compressor won't engage unless I jump it through the relay. I have the tech2 in the car so when I get home I'll check the switch
 

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Don't forget, on a Tech2 the A/C information is in 2 different places. Not sure I'm remembering correctly, but powertrain and body?
 

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2002 chevy trailblazer_lt
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My suspicion runs towards the access port or valved connection of the hose set/vehicle.

You don't have those knobs at the vehicle connection turned out counterclockwise, correct? If those are turned out counterclockwose the ports are closed and all you are vacuuming is the gauge set and hoses. Same at recharge.
 

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2006 chevy trailblazer 4.2l from a 2004 trailblazer
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Discussion Starter · #9 ·
My suspicion runs towards the access port or valved connection of the hose set/vehicle.

You don't have those knobs at the vehicle connection turned out counterclockwise, correct? If those are turned out counterclockwose the ports are closed and all you are vacuuming is the gauge set and hoses. Same at recharge.
They are turned clockwise, I've tried changing everything once already lol. And I'll look around with the tech2 when I get home. I left to go shopping
 

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Ok, just checking all bases here. You have a highly unusual situation. The Tech 2 (I have one also) will not help here other than perhaps corroborating the high pressure gauge.

If I were in your place I would do a test to show the system doesn't have a complege blockage somewhere. Loosen the hose connections on the gauge set, let any pressure escape and verify both gauges read zero. Retighten the hoses. Hook up the gauge set and vacuum as you have shown. Open both service access valves at the vehicle service ports fully clockwise. Open the blue low side valve at the gauge set. CLOSE the red high side gauge at the gauge set. Turn on the vacuum pump and observe the high side gauge. The idea here is to show that vacuum applied at the low port is seen at the high port.
 

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2006 chevy trailblazer 4.2l from a 2004 trailblazer
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Discussion Starter · #11 ·
Heading home I'll give it a shot
 

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Discussion Starter · #12 · (Edited)
Ok, just checking all bases here. You have a highly unusual situation. The Tech 2 (I have one also) will not help here other than perhaps corroborating the high pressure gauge.

If I were in your place I would do a test to show the system doesn't have a complege blockage somewhere. Loosen the hose connections on the gauge set, let any pressure escape and verify both gauges read zero. Retighten the hoses. Hook up the gauge set and vacuum as you have shown. Open both service access valves at the vehicle service ports fully clockwise. Open the blue low side valve at the gauge set. CLOSE the red high side gauge at the gauge set. Turn on the vacuum pump and observe the high side gauge. The idea here is to show that vacuum applied at the low port is seen at the high port.
I did that the low side gets vacuum the high side does not. I'm totally lost at what to try and do. I'm not sure how to test if my service ports are even any good.
 

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2006 chevy trailblazer 4.2l from a 2004 trailblazer
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Discussion Starter · #13 ·
Figured it out guys. The low side service port was stuck even with the manifold hooked up it wasn't reading the system vacuum/pressure. A buddy came over and realized it. He swapped out the low side stem insert and I could vacuum the system. Now when adding freon the low side guage seems accurate and is engaging the clutch on its own. The high side we still can't get a reading from but as I can get cold air for now I won't bother fixing it. Thank you everyone for helping out and giving me things to look for :) vents are cold now
 
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