97 tahoe AC problems

[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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