97 tahoe AC problems

[Marbor]

Good morning to all hope someone can help me out here.
My issue is the rear AC hose was busted so I disconnected and topped off. In the process I recharge with dye and was working for a few days then went hot and no AC. I black light to find the leak and the condensor was shot. I replaced the condensor vac out let it sit for more then an hour at -27 psi no movement so I proceeded to charge. I added the small 3oz can of dye stop leak and a 12 oz can of refrigerate. AC clutch kicked on and all seemed normal until I noticed my low side gauge is clocking over 100psi and my high side is pushing past 400 450 mark. Seems to me overly charged badly a little cold air And compressor is kicking on every min or so. What could be tge cause any help would be appreciated.

 

[Marbor]

Good morning to all hope someone can help me out here.
My issue is the rear AC hose was busted so I disconnected and topped off. In the process I recharge with dye and was working for a few days then went hot and no AC. I black light to find the leak and the condensor was shot. I replaced the condensor vac out let it sit for more then an hour at -27 psi no movement so I proceeded to charge. I added the small 3oz can of dye stop leak and a 12 oz can of refrigerate. AC clutch kicked on and all seemed normal until I noticed my low side gauge is clocking over 100psi and my high side is pushing past 400 450 mark. Seems to me overly charged badly a little cold air And compressor is kicking on every min or so. What could be tge cause any help would be appreciated.

To add in prior to replacing the condensor the system had 0 pressure on both sides

 

[96-2D-Hoe]

Not sure about the gauge readings, could there still be air in there? That would give you higher than normal pressures.

My 96 2 door with no rear AC takes 48 oz / 3lbs gas, if you only added 12oz you are still way short, but I don't think you should be hitting 100psi on the low side. When charging my old/original compressor cycles around 20-50PSI

 

[OR VietVet]

https://www.rockauto.com/en/moreinfo.php?pk=84624&cc=1061367&jsn=2266

https://www.rockauto.com/en/moreinfo.php?pk=83072&cc=1061367&jsn=2285

https://www.rockauto.com/en/moreinfo.php?pk=8320853&jsn=2330

https://www.rockauto.com/en/moreinfo.php?pk=7934548&jsn=2350

Did you put oil back in the system and if so, how much. The links show the other items that should have been done when you did the work. Just slapping in a new part without flushing and replacing accumulator and orifice is not recommended and can lead to problems.

 

[Marbor]

No oil just refrigerate here is the deal 1st time system was dead I had my friend at shop clear the system then I added the peg oil 3 oz and re charged 45 oz worked for a day or so then went bad found issue condensor and replaced no pressure in the system. Re filled with a can and a half from what was left in the 1st round and had this high pressuer issue. Just went out and hooked up and pressure was low running around 20lbs no compressor kicking on added a half can and compressor kicked on with vary mild AC. I'm guessing there's another leak somewhere will wait till dak huts and search with black light since the can had a mix of leak fix and dye.

 

[OR VietVet]

Likely another leak and should do the other items I listed and never add refrigerant to a system that has not been evacuated, like you did after the condenser replacement.

 

[wjburken]

@UmmScott might have some ideas.

 

[96-2D-Hoe]

Definitely want to replace the orifice tube whenever you can. As your system has been open so much you should also change the accumulator/drier like Ron suggested. Sounds like you did still have air in it.
For leak detection you can't beat strong soapy water, and use a sponge to make up foam. Cover the connections in the foam and look for bubbles. Tiny leaks will normally make one bubble that keeps getting bigger, a stronger leak will create a stream of bubbles. But that wouldn't find a leaking condenser. Good luck.

PS.
The HT-6 / original compressor has a history of leaking, it's not called a belly leaker for nothing. I'm pretty sure mine leaks.
The stop leak is junk that will clog up your system. Don't use it, just find and fix any leaks.

 

[Marbor]

Likely another leak and should do the other items I listed and never add refrigerant to a system that has not been evacuated, like you did after the condenser replacement.[/QUOTE

Prior to adding refrigerate I did evac the system as I stated prior i had it sitting at -27 psi for over an hour while I had a few drinks and BBQ lol
After all that I then added the refrigerate then the high psi issue happened. Am I missing something on the evac part??

 

[96-2D-Hoe]

"Am I missing something on the evac part??"

No, but if the system is still leaking you will be drawing air in. -30PSI is where it should be but the gauge can be off a bit. What I do is listen for the change in tone from the vacuum pump as well as check the gauge. When you think your vac is done shut your gauge down and let it sit. Flick the gauge to make sure it doesn't move. But after 30 mins or so start your vac pump up again and open the gauge. If it has a full vacuum the tone of the pump will not change when you open the gauge, but if it does it means it's not a full vacuum and you are likely leaking or still have gas evaporating from the oil.

 

[OR VietVet]

The only way to pull 30 inches of vacuum is to be at sea level. Anything above sea level will be closer to 28" or less depending on the elevation.

 

[UmmScott]

You're shooting yourself in the foot with the stop leak stuff.
Stay away from that.

That stuff will clog up the small passages in the condenser coil and basically render the system useless. Especially in your case since you had a hose blowout

There is probably moisture in your system and thats what you're fighting. There are only 2 things that belong in any AC and refrigeration system: refrigerant and oil. (And MAYBE UV dye)

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[Marbor]

Thanks for all the responses im thinking back to square 1 after I find and repair the leak also going to change dryer as well to insure efficiency plus its pretty cheap.
I will update when I see get results

 

[UmmScott]

The key to a properly functioning AC system is being leak free, ZERO moisture, clean condenser coil, and properly functioning radiator fans.

If your system leaks, then its useless to pull a vacuum cuz youll just pull air right in and make things worse.
Its good to cover all the bases and make sure you understand how it all works before diving in.
Let us know the results man [emoji106][emoji106]

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[96-2D-Hoe]

Don't forget to change the orifice tube. It is behind the passenger side lower headlight that you remove to access it. Any time your system has lost gas without a major leak, like the compressor leaking, you should swap that out for a new one. It has a screen in it that collects crap and can get blocked. They cost a couple $'s and take 5 mins to change if the gas is lost already.
Pretty sure my compressor is leaking. My system never goes below 5psi or so. So I just swap mine out, quick vac and weigh3lbs liquid back in. If the system were at 0 PSI you should change the accumulator/drier as well as the orifice tube.

 

[Matthew Jeschke]

I recently completely disassembled and reconditioned my 2001 tahoe HVAC system.

450 PSI is overcharged, no doubt. You said you disconnected the rear air conditioning? Elaborate? Did you remove the refrigerant line & evap? Or just the electrical controls?

PV= nRT... Your volume is off no? 450 PSI tells me your overcharged... Makes me think you removed volume from system / rear coil?

That said, there's no easy way to delete the rear evap coil in my 2001 Tahoe. I'd honestly, rebuild the system as one. Doing it all as one (assuming serviceable parts only) is very inexpensive. It's also designed to work together. I bought a very inexpensive kit from autozone including dryer, orings, oriphis tube, and expansion valve for rear coil.

- I took all the lines off and cleaned them out with starter fluid / ether (awesome solvent / cleaner).
- Same process on all the heat exchangers
- Blew them out with compressed air
- I had pulled the compressor off (optional) got a little catch can and drained as much oil as I could.
- I made note of how much oil I drained.
- This allowed me to make a SEMI informed estimate on how much oil to add back in. Honestly, it's damn hard to know for certain w/o complete rebuild.
- Next put back together adding nylog / refrigerant compatible gasket conditioner to all the orings.
- Pulled a vacuum for several hours and watched it hold.

- Next I charged with dust off (cheaper than refrigerant but slightly flammable) to do a positive pressure test.
- Lastly I vacuuumed again.
- Recharged with pure refrigerant NO STOP LEAK NEVER PUT ADDITIVES IN YOUR AC unless manufacturer calls for them.

Last note, I used AllDataDiy.com subscription to get the factory specs on the system. There's TONS of crappy AC advise on the internet... And Chilton's / Haynes manuals have enough info to get you into trouble but not much to get you out.

 

[96-2D-Hoe]

Your volume is off no? 450 PSI tells me your overcharged

FYI That's what happens when you have air in the system.

 

[georgebuhr]

My guess is that you over oiled it. 3 oz is way too much oil for what you replaced. My suggestion is this, seems how you are starting over anyway. Get a Kit to flush the lines, and also while you are at it, drain the oil from the compressor . Also replace the dryer and orifice tube. Figure out how much oil goes in the system, and put that in the compressor and reinstall. Vacuum the system for minimum of thirty minutes, shut off vacuum, monitor gauges for vacuum. If it doesn’t fall off in 30 minutes, you have no leaks. Start with adding one pound of freon seems how the rear is disconnected, and check your gauges. 100 psi is high for low side, but I can’t tell you what is correct because it depends on the ambient temperature at the time. Google an ac chart and it should show you what your pressures should be. But if you get the oil right, charge right, and the dryer is good you should be fine.

 

[georgebuhr]

Oh and anywhere there is an oring, lube it with PAG oil before you put it back together.

 

[Matthew Jeschke]

Oh and anywhere there is an oring, lube it with PAG oil before you put it back together.

I recommend nylog. it is pag but in gewey form. I think I bought it off amazon.

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