It kind of worked last year but barely. Yesterday I flushed the system by

  • Flushing AC cleaning solvent from the high end out the low end. I did not disconnect the hose but instead pushed the pin in on the low end so the solvent could make its way through. I then blew air through the system until only air was coming out.

Today I replaced the AC compressor with a new compressor. I then topped off the system with oil (PAG-46, compressor came with 3oz, I added the remaining 4 ounces through the low port). Then I started the engine, put AC on high and added R-134a until the fill gauge was in green. If I add too much I can hear the compressor cycle on and off but depressing the pin on the high side brings the pressure back down and the fill gauge is currently stable in the top 3/4 of the green section (not in the yellow or red sections).

The AC doesn't blow cold at all. As far as I can tell there is zero difference between having the AC on and just using the regular fan.

I've heard if you don't vacuum the system it won't give you maximum performance but since I am getting zero performance I don't know if that's the main culprit.

One additional piece of information is whenever I use the defroster the windows fog up. So maybe there is moisture in some part of the system but idk if that would effect the AC.

Could it be the condenser? I'll replace it but I know it will be a big pain in the butt and I don't want to waste even more money on this.

1 Answer 1


Vacuuming the system isn't a "do if you want to" ... it is a must do if you want the system to work. There are two reasons to vacuum the system before entering refrigerant. First, it gets all atmosphere out of the system. Atmosphere will not work as a refrigerant and will keep the system from working correctly. Secondly, you vacuum the system to ensure there aren't any leaks. You do this by keeping it under vacuum for 30 minutes or so and reading the gauge to ensure you're not re-introducing atmosphere back into the system. If good, it also tells you the system will then hold refrigerant.

From what you've stated, since you've not vacuumed, this is most likely your issue. You may have other issues, but until you do this, you won't know what the other issues might be.

  • Okay good to know. Question. Wouldn't the vacuum suck out the oil that comes with the compressor? So if you install the compressor and vacuum right away what is the point of putting it in there in the first place? Or does it not suck that oil out?
    – user875234
    Apr 29, 2021 at 16:58
  • Doesn't mess with it at all. Bottom line, either you vacuum it out or you'll be spending a bunch of time changing parts which didn't need changing in the first place. I need to modify one thing I stated above. Not vacuuming your system is most likely your issue. It is definitely an issue. You may have other problems going forward. Without purging your system of air, you won't know what the next step is (if one is needed). Apr 29, 2021 at 17:18
  • 3
    Drawing down the system also is effective at removing moisture, which could otherwise cause problems like ice clogged orifice in the expansion valve.
    – mongo
    Apr 29, 2021 at 17:46
  • You mention that the windows steam up with the AC on. This would not be from moisture inside the AC system cooling loop. It COULD be from moisture inside the evaporator area, which is humidifying the air. It is not uncommon to have the evaporator drain, which drains condensate, get clogged. That moisture can cause freeze damage to the evaporator. What are your hi/lo pressures?
    – mongo
    Apr 29, 2021 at 18:12
  • 1
    One more comment on evac...if there is moisture, an overnight with vac drawn will boil off any moisture rather well. Draw the vac, close the service set valves and let it sit overnight. (I once dried out a GPS in a spray paint can (pot) overnight with a similar setup. The moisture in the GPS was effectively extracted.)
    – mongo
    Apr 29, 2021 at 19:05

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