A/C System Diagnosis and Repair Help

Discuss any maintenance you've done to your Vibe & Matrix and ask how to perform maintenance on your vehicle
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cthomasparr
Posts: 134
Joined: Sat Jan 16, 2010 10:03 pm

A/C System Diagnosis and Repair Help

Post by cthomasparr »

Of course, when your A/C quits it has to happen when the temperatures are 90+ degrees in July.

My system wasn't running great up to this point, but it became noticeable yesterday that the ac wasn't cooling.

I was hoping it might be a recharge issue, so I got a can of a/c pro from the garage and hooked it up to the low side. Reading was in the red with the A/C on. A/C compressor was engaged and spinning.

I haven't given this a lot of investigation, but I think a faulty compressor could cause this. With the A/C off the whole system is charged pretty high. When the compressor comes on I believe it causes a higher high and a lower low side.

Can anyone out there tell me what kinds of issues they have had with their vibe a/c. I would like to know what the most common failures are.

I have gotten a lot of use from the car 2004 with 250K miles and, even though I don't use the A/C often...

I have a gauge set that I will hook to the car this weekend. Should show me if there is a pressure difference between low and high with the compressor running. maybe there are issues elsewhere.
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Chiadog
Posts: 971
Joined: Thu Aug 09, 2012 9:41 am
Location: Abrams, wisconsin

Re: A/C System Diagnosis and Repair Help

Post by Chiadog »

The AC condenser is more likely to become plugged with debris and therefore less efficient at removing heat as the miles accumulate. (250K miles!)
cthomasparr
Posts: 134
Joined: Sat Jan 16, 2010 10:03 pm

Re: A/C System Diagnosis and Repair Help

Post by cthomasparr »

Thanks chiadog. Wonder if that could explain my high pressure on the low pressure side.
cthomasparr
Posts: 134
Joined: Sat Jan 16, 2010 10:03 pm

Re: A/C System Diagnosis and Repair Help

Post by cthomasparr »

I hooked up a gauge set and the low side and high side readings were:

idle with a/c off low 116, high 125
a/c on low 93 high 132

From what I have seen, the high side should be somewhere between 180 and 200 psi and the low side about 30 to 45. Looks like my compressor may be gone.
gtv237
Posts: 387
Joined: Fri May 23, 2014 6:21 pm

Re: A/C System Diagnosis and Repair Help

Post by gtv237 »

Way too high on the low side. High low side pressure is usually due to an overcharge. Overcharging also wrecks compressors so that would explain the low high side readings.
cthomasparr
Posts: 134
Joined: Sat Jan 16, 2010 10:03 pm

Re: A/C System Diagnosis and Repair Help

Post by cthomasparr »

I had never charged the system since I bought it in 2010. It worked fine until recently. When I went to add freon low side was in the red zone. It could be the sign of a failing compressor that doesn't pull a vacuum while pressurizing the high side. I should have seen if there was any change at higher rpm.
cptnsolo77
Posts: 1645
Joined: Sun Jul 29, 2007 4:05 am

Re: A/C System Diagnosis and Repair Help

Post by cptnsolo77 »

This past spring my low side was HIGH and high side was LOW. Turned out to be a bad compressor :(
* 2003 Vibe Auto Satellite Silver w / Moons & Tunes
* Kenwood Excelon KDC-X597
* Polk DB651-Speakers
* Soundproofcow Roadblock R sound deadening in all doors
* Drop In K & N Filter
* NGK Iridium IX Plugs
* 27 MPG City/Highway with AC on
cthomasparr
Posts: 134
Joined: Sat Jan 16, 2010 10:03 pm

Re: A/C System Diagnosis and Repair Help

Post by cthomasparr »

Were the high and low side pressures almost the same? Asking if low was higher than expected and high was lower than expected but low wasn't higher than high.. If that makes sense.

Bigger question is did you get the compressor replaced and did it work? Did you replace any other parts?
cptnsolo77
Posts: 1645
Joined: Sun Jul 29, 2007 4:05 am

Re: A/C System Diagnosis and Repair Help

Post by cptnsolo77 »

Ok I just dug up some service records. Low side was 60, high side was 160. Compressor was bad. I replaced it myself with a OEM compressor from amazon. Not difficult at all. I did take to a auto AC shop where they pressure tested and charged it for $100. If you can find a reputable AC shop take it there for a final decsion. When the guy said the compressor is shot....I took it from there :D
* 2003 Vibe Auto Satellite Silver w / Moons & Tunes
* Kenwood Excelon KDC-X597
* Polk DB651-Speakers
* Soundproofcow Roadblock R sound deadening in all doors
* Drop In K & N Filter
* NGK Iridium IX Plugs
* 27 MPG City/Highway with AC on
cthomasparr
Posts: 134
Joined: Sat Jan 16, 2010 10:03 pm

Update

Post by cthomasparr »

I decided to purchase a used compressor from Ebay and bought a new reciever dryer mount from Amazon.

I took off the bumper cover and radiator fan to get better access to the A/C components.

One thing I noticed is that all of the seals for the reciever dryer and compressor lines are steel washers with rubber built in. I didn't know what to expect. Guess I was thinking they would be green orings. I took them to the local NAPA and they sized up replacements that looked identical. About $2 each. Also replaced the rubber oring between the pressure sensor and receiver dryer.

Somewhere I read to put 2oz oil in for a new receiver dryer. I should probably have added it right to the r/d but I followed the youtube videos I had seen and added it to the line I was using to charge the system. I think the total capacity of the interior of that hose was about 2oz. If I followed their purge suggestions I would have blown the oil out.

When I started to do the system charge, the new compressor clutch didn't engage. The pressure pretty quickly rose to about 90psi. I shut things down and took off the compressor wire and put my old compressor close enough so I could plug it in. Grounded its body and restarted the car. With the a/c on, the old clutch engaged. Damn ebay. the "new" compressor clutch is not working.

Currently swapping out my old compressor clutch with the replacement compressor's clutch. The snap rings on the clutch were too much for my smaller snap ring pliers so I took a very large snap ring plier set I had from harbor freight and filed down the tips until they could fit. Will try tonight
cthomasparr
Posts: 134
Joined: Sat Jan 16, 2010 10:03 pm

Re: A/C System Diagnosis and Repair Help

Post by cthomasparr »

I swapped the ac clutch with compressor in the car. Was painful because of the snaprings but got it done. I am happy to say that I have cold air and a low side pressure at 55 with a high side at 175 at idle. Good numbers I think.

I did stumble a bit with my harbor freight gauge set. Mostly because I failed to open the valves by the high and low port all the way. Made filling pressure shoot up more than it should have and the high side wasn't registering. I thought the fix went bust but I noticed cold air in the vents. When I completely opened both valves the measurements made more sense.

Another thing I forgot to mention was the receiver dryer that I purchased didn't come with a mount/holder. I had to modify the plastic one holding the old r/d. The new unit was actually a different size . I had to remove enough ofbthe plastic to get the old one out and then used a hose clamp to hold the new one in. I had to remove the entire curved bottom of the mount to accommodate the longer r/d.
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