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A/C Gauge Readings: 80 low / 150 high?

Tiny
TVSTEINKE
  • MEMBER
  • 2012 TOYOTA AVALON
  • 3.5L
  • V6
  • AUTOMATIC
  • 130,000 MILES
This is my neighbor's car. Neighbor says she drives for 30 minutes and gets cold air just fine, but then it stops blowing cold and blows hot. It's happened several days in a row. I put a thermometer in the duct and it's blowing 45-50 degrees.

I couldn't replicate the problem. I put gauges on after running it, and it took about 30 minutes for the pressures to equalize, which I've never seen. When not running, pressures were 80 on an 85-degree day. When running, pressure was steady at 80 on low and 150 on high.

I had noticed that the air coming out wasn't blowing particularly strongly, so I checked the cabin air filter, and I pulled out what may have been the original one. Very densely packed debris and torn pleats. I ran it without a filter thinking that it may have resulted in a frozen evaporator, but that did not solve the problem.

Can anyone point me in a direction to check? Thanks for taking the time to read this!
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Saturday, August 5th, 2023 AT 2:52 AM

10 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
This sounds like the compressor is going out. Here is a generic guide to help you step by step with instructions in the diagrams below to show you how on your car:

https://www.2carpros.com/articles/replace-air-conditioner-compressor

Please go over this guide as well:

https://youtu.be/4EqdrBVb0sY

Check out the images (below). Please let us know if you need anything else to get the problem fixed.
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Saturday, August 5th, 2023 AT 11:33 AM
Tiny
TVSTEINKE
  • MEMBER
  • 6 POSTS
Thank you very much! I especially appreciate the diagrams.

Does this sort of gauge reading ever make you think the expansion valve is failing or somehow blocked? I do not want to have to tear into the dash to get to that, but I also want to be sure to fix the problem. On my own car, it's easy to get to the valve so I'd replace it anyway (just like I'll replace the condenser when I put in this compressor). But I'd be happy to just leave the old expansion valve where it is if it's not likely to be the problem.
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Sunday, August 6th, 2023 AT 3:55 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
I don't think it is the expansion valve they rarely go out unless the compressor has come apart and spread compressor seal material throughout the A/C system, when you remove the hoses from the compressor look to see when the inside of the system looks like. Please let me know.
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Monday, August 7th, 2023 AT 10:02 AM
Tiny
TVSTEINKE
  • MEMBER
  • 6 POSTS
Thanks a bunch! I noticed that you sent me to a video, and that it's your YouTube channel. Subscribed!
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Monday, August 7th, 2023 AT 10:54 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Yay! Thank you, we try to help. Let me know what happens with the A/C problem.
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Tuesday, August 8th, 2023 AT 10:04 AM
Tiny
TVSTEINKE
  • MEMBER
  • 6 POSTS
Follow-up: Today I took the new compressor (UAC brand) and turned it upside down to drain out the pre-installed PAG oil, but none came out. Curious, I then took the old compressor and turned it upside down, and none came out of that, either. So, I figured "these compressors must hold the oil in a reservoir of some kind." There was no drain bolt. So I got everything installed and was doing a vacuum draw down when I noticed a sheet of instructions that came with the compressor, and it specifically said to turn the compressor upside down and "discard the oil that came with the compressor, and fill the compressor with half the PAG oil specified by the car manufacturer and put the rest into other components." That made me realize there's not some magic reservoir that doesn't drain out of the openings. So, now I have a fully-installed system that I do not want to have to take apart again. Am I right in concluding that the compressor manufacturer did not put any oil in compressor, since none drained out? And, can I just add the whole charge of PAG oil to the low pressure side to work its way into the compressor, or will that ruin the compressor? Any advice much appreciated!
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Wednesday, August 30th, 2023 AT 12:05 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
That is hard to say, it sounds like no oil came in the compressor but can I ask if you turned the clutch while trying to drain it? If so then the compressor sounds dry and will need an oil charge. Please let me know how it goes.
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Wednesday, August 30th, 2023 AT 10:51 AM
Tiny
TVSTEINKE
  • MEMBER
  • 6 POSTS
Thanks for the quick response!

I did turn the clutch while holding the compressor upside down to see if that released any oil. It did not. Same with both the new one and the old one.
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Wednesday, August 30th, 2023 AT 10:54 AM
Tiny
TVSTEINKE
  • MEMBER
  • 6 POSTS
I ended up dividing the remaining oil between a low sideline near the compressor (about 2/3 of the oil) and a high sideline. It seems to be working just fine. Thank you very much for your willingness to help!
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Wednesday, August 30th, 2023 AT 9:40 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Thanks for letting us know, we are here to help, please use 2CarPros anytime.
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Thursday, August 31st, 2023 AT 11:09 AM

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