A/C not working after rebuilding system?

Tiny
JUANEMMANUEL
  • MEMBER
  • 1998 BUICK RIVIERA
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 172,000 MILES
I confirmed that the compressor had failed because the manifiold gauges read 120 psi on both high and low side. I replaced the compressor, condenser, accumulator, and orifice tube (which was covered with metal shavings)
I has the AC rubber hoses fitted with new ones and the small muffler removed.
I flushed the evaporator and used compressed air to remove every last drop.
I removed all the oil the new compressor came, about 6.3oz of pag 46, and added 6oz of new pag 46 oil with dye, and put another 3oz of oil in the accumulator (system calls for 9oz total)
I lubed the o-rings at every connection with pag oil.
After putting everything back together, I ran the vacuum pump for 1 hour, and waited another hour, and it held the vacuum fine.
I started charging the system with r134 freon and this is where problems began.

I purged the yellow line at the Manifold gauge and was waiting to see a puff of gas come out but it never did. Instead when I pressed the schrader valve I could just hear air leaking out. After doing it a few times I started the car and turned on the AC and the freon started going in. But I noticed that the compressor was not engaging. I finished charging the system with 2 cans and a half of freon (system calls for 32oz total)
Cluth still wouldn't engage and no cold air inside the cabin. I swapped out the AC Compressor and Horn Relays and the Horn worked fine with both, but the Compressor wouldn't run with neither.

I used a paper clip to bridge the correct pins in the relay box, and the compressor finally engaged.
I left it running for a while with the AC turned on but still no cold air.
I removed the paper clip and started the car and the AC with the relay inserted again, but the AC clutch won't engage.
Any ideas are appreciated.
Sunday, March 31st, 2024 AT 7:41 AM

5 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
When the compressor was running what were the high and low side pressures? Also, I would remove the low side pressure sensor and use a jumper wire to see if the compressor engages. Most of the time when the compressor comes apart internally like this you should replace the condenser because this is where the compressor seal material ends up and clogs it up. Please go over this guide which can help and get back to me with the pressures.

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

Check out the images (below). Let us know how it goes.
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Sunday, March 31st, 2024 AT 7:38 PM
Tiny
JUANEMMANUEL
  • MEMBER
  • 48 POSTS
I changed the condenser. Turns out I had a leak where the line coming from the compressor connects to the condenser. I put a double o-ring and re-tightened the connection. I put a vacuum on it again and after checking the pressure in 15 minutes it went back to zero. I went ahead and charged some freon from a bottle with a gauge and a hose until needle went to green/charged and this time the compressor clutch turned on by itself. But still, there's no cold air in the cabin. The freon level is good because the needle on gauge is still in the green. And the A/C actuator works because the air comes out of different sections when I select them. What else could be the problem?
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Monday, April 1st, 2024 AT 7:57 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Can you tell me if the low side line coming from the fire wall is cold when the A/C is on? If not, it sounds like the orifice tube is clogged. Here is the location of the tube so you can check t out, please upload images of the orifice tube once you have removed it.
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Tuesday, April 2nd, 2024 AT 8:19 AM
Tiny
JUANEMMANUEL
  • MEMBER
  • 48 POSTS
It finally worked!
It was just too low on refrigerant. I charged another 32oz of R134 and it's finally nice and cold. So, the first time it didn't work because there was a leak. And the second time I simply didn't put enough refrigerant because I wanted to see if a little made any difference, which it didn't. Thanks again for all the info. The pressure readings I ended up with are 37 PSI on the low side, 207 PSI on the high side.
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Tuesday, April 2nd, 2024 AT 5:57 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.
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Tuesday, April 2nd, 2024 AT 8:49 PM

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