A/C refrigerant

JAMESB2019

MEMBER
2006 PONTIAC G6
3.9L
6 CYL
2WD
AUTOMATIC
150,000 MILES

I have 3 questions concerning A/C recharging:

can a vacuum be pulled on the A/C system and then charged later or does recharging the system have to be done immediately after?

If the low pressure line is subjected to physical blockage right before it enters the TXV, can the blocked line be discovered when a vacuum is pulled on the system?

I have overhauled the entire HVAC system (new compressor, condenser, lines, evaporator core and heater core). I added a total of 5 fl oz of pag oil per instruction (1.5 evaporator, 2.5 compressor and 1.0 to condenser). After the vacuum is pulled, will the oil need be replaced or does the vacuum not affect the oil?

9 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning,

After evacuating, I would not leave it in a vacuum for an extended period of time. I would charge it within about an hour. It will also tell you if you have a leak by lowering the amount of the pull.

No, it will not. During the evacuation, a vacuum is pulled on both sides at the same time. It will not tell you if there is a blockage at all.

No, the evacuation will not remove the oil. When you recover the freon from the system, the oil will come out. There should be little if any that comes out. You need to measure it and whatever came out must be installed before charging.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Roy

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Thursday, June 3rd, 2021 AT 3:00 AM

JAMESB2019

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Thanks Roy.

James

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Friday, June 4th, 2021 AT 8:50 AM

ASEMASTER6371

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You are welcome.

Always glad to help.

Roy

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Friday, June 4th, 2021 AT 1:17 PM

JAMESB2019

MEMBER
42 POSTS

So, all went okay during the evacuation and recharging. There were no leaks. No oil came out at all (I suppose because all the parts were new and the oil I added during installation was still in the liquid state). I did the recharging using a can tap and a set of gauge manifold. Humidity was high and the temperature was about 75 to 80 F. At the end of the procedure, the Low Pressure reading was around 38 and the High Pressure reading was around 165.
Thanks again.

James

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Monday, June 7th, 2021 AT 11:32 AM

ASEMASTER6371

MECHANIC
52,797 POSTS

Okay, the high side is spot on but the low side is high. It should be 25-30 pounds.

How cold is the air coming out of the vents?

The TXV or expansion valve is the reason the low side pressure is too high. I attached the procedure for you for the repair.

Roy

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