Another hopeless wanderer

[Greenmonster71]

Hi all, apologies for being another bozo on the bus checking in to the first forum I can find on google regarding the subject at hand.

I do know that I don’t mind sharing insight on things I have expertise in that may benefit others who do not know them as well.

In that spirit, I hope someone will be kind enough to indulge me with some of their expertise.

Hot Mississippi gulf coast summer, can’t get ac working.

Case study at hand: 2005 trailblazer ext with rear ac. I have replaced compressor with new compressor and a new accumulator and a new orifice tube. Compressor came with 5.3 oz of Pag oil, I added another 3. I also added an ounce to new accumulator. I also sought to replace orifice tube for rear ac, but it was a different kind so I cleaned it with a steam gun.

I vacuumed system and loaded system with 48oz of r134a as this is how much my system calls for via the internet…

Ac compressor will not engage on its own. I have checked relay is good, will cut on for about 5 seconds upon initial crank then shuts down. I suspected possible bad low pressure switch or high pressure switch, because when I jump the compressor it blows ice cold air, beautifully . I will just run a switch to jump the relay if I have too, as this is just a back and forth to work car and I’m tired of not having ac, but I don’t want to blow up the compressor or bust a seal or damage compressor from having it continuously running.

So, even though I sought to avoid the need for my manifold gauges, by simply charging empty system with called for amount of refrigerant, I decided to go ahead and pull them out to check the high and low pressures . It’s probably 90 degrees out with 100% hunidity right now.

At any rate I had no luck with the ac. I hooked up the gauges and jumped the ac to turn the compressor on . The low side was at 75 psi and high side 200 psi.

Ok easy enough ive got to much pressure , maybe the internet told me wrong on the charge amount , maybe I only have dual control and not rear ac , maybe I’ve got several ounces too many of pag oil in there I don’t know . At any rate I should be able to drop my low side pressure to 45 and be good.

We’ll this is where it gets weird . So needle on high side is just flittering right on 200, low side is at 75, so I start recovering refrigerant on low side. It takes way to much refrigerant being recovered to drop psi. I mean I’m pretty sure I recovered all the damn refrigerant and the gauge still reads 50 psi on low side and almost 200 on high side. I am submitting picture of where I finally stopped recovering refrigerant and stepped away from the vehicle . But my accumulator is not sweating, ac blowing hot, and when I recover refrigerant from low side it’s just like air and not refrigerant. When I recover from high side some oil also is recovered, but even with the few short spurts I recovered from the high side it didn’t really drop needle much on pressure .

Is it possible that I have to much oil in there putting pressure on system even without much refrigerant ?

Should I have been recovering from the high side ? Did I accidentally recover all from the low side and the high pressure side is just so full that it’s not operating right and holding pressure on the low side as well?

Are my gauges bad ? They drop to zero when I open them and they aren’t hooked up to car. I could see them dropping pressure when I would open line to recover some refrigerant, but as soon as I closed them pressures would return to same .

I’m about to just vacuum the system again , fill it up with 48 oz of Freon and run a switched jumper to compressor relay just to have ac in my car . I don’t know what’s going on.


Does anybody have any ideas ? Thank for your patience and indulging me.


Can’t post pictures because max file size is 267kb.

[bohica2xo]

Probably need to start with whether or not you have rear AC.

Your first test pressures were in line with what I would expect for an idle test with a high heat load like that.

[Tim]

Air Conditioning Refrigerant .................... 1.9 lb (0.86 kg)
Air Conditioning Refrigerant with Rear A/C .................... 2.65 lb (1.2 kg)

REFRIGERANT OIL CAPACITIES


Total System Oil Capacity .................... 240 ml (8.0 oz)

[tbirdtbird]

Your old comp grenaded, and you did not replace the condenser, which is now loaded with debris and shrapnel from the destroyed comp. The proof of this is the OT had to be steam cleaned.
IMO you are gonna have to start over, you have shrapnel everywhere.
Typically the rear is a TXV and the front is an OT. Your owner's manual should clarify just what kind of system you have.
Glad you have gauges, virtually impossible to do AC work without them. They sound OK to me
It is a shame you did not find this site before you started. But we will help you the best we can

[JohnHere]

The specs that I have for your vehicle agree with those that Tim posted.

Incidentally, in your original post, I'm sure you meant to say "I recovered refrigerant" or something similar. Therefore, I edited your post accordingly.