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A/C Blockage? - Update with problem fixed.

Desp on Sun April 05, 2009 12:29 AM User is offline

Year: 1996
Make: Saturn
Model: SL1
Refrigerant Type: R134
Ambient Temp: 70
Pressure Low: 0
Pressure High: 100

I'll try to make this as understandable as possible.

My AC system didn't work, thought it had a leak, vacuumed it to 29+Hg, held it for over an hour, refilled system. Put in 24 oz. and the high reading was 95 and the low was around 10/15 at 2000 RPM. No cold air. Figured OK, maybe the compressor is leaking or it's just not compressing correctly (And the person that I bought the car from, said it had a bad compressor). So I bought a new compressor, added oil, vacuumed system, once again held vacuum. Recharged it. this time it went up to around 100 PSI on the high and 0 on the low. I revved the engine to around 4000 and it pulled a vacuum on the low around 15Hg. My next thought process was OK, it's obviously blocked. I have also been informed its a requirement to replace the drier when you replace the compressor, so I bought a new drier. Here's where I'm at now.
I'm planning on taking all of the components out of the system, flushing everything minus the drier, compressor and expansion valve, with an A/C flush fluid, if nothing is damaged reassemble everything, add oil to the system, vacuum, recharge and everything should work, right?

I tried to use compressed air to blow into the high side and see if any air would come out of the low side, nothing came out. Complete blockage? How hard is it going to be to remove the evaporator? Let me know if I've missed anything. I've already invested to much time, and money into having to take this somewhere, I have to fix it myself now, I will not be defeated!




Edited: Thu April 23, 2009 at 9:50 AM by Desp

robs on Sun April 05, 2009 3:21 AM User is offlineView users profile

Please click HERE to read into how to properly flush a system. And as a tip, it is highly recommended that every time a compressor is changed, to not only flush the system or replace the drier/accumulator, but to also replace the expansion device and condenser (if not flushable).

Chick on Sun April 05, 2009 5:10 AM User is offlineView users profile

As rob stated, there is usually more work to be done than just changing the compressor. It depends on the original failure. In your case, the expansion valve is suspect, change it along with the drier. Check the oil for contaminates, flush the system if needed..Hope this helps..



96 Saturn parts from Ackits.com

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

GM Tech on Sun April 05, 2009 12:46 PM User is offline

those rotary vane pumps need to have a complete charge in them to get them pumping- seen it several times- slow to build high side pressures- I usually overcharge for awhile to get them going--- then ruduce the charge to spec...I highly doubt you have a blockage....

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

TRB on Sun April 05, 2009 7:58 PM User is offlineView users profile

Was a sealer ever used in this system.

I have concerns that it is truly blocked as your readings would be different and doubt you would have gotten the full 24 ounces in the system. Unless you charge by R&R machine?

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

bohica2xo on Sun April 05, 2009 9:13 PM User is offline

2 compressors, plenty of oil....

Time to break it down & flush for sure.

If you suspect a blockage (and see vacuum on the low side!), it is time to inspect the expansion device. Go find This little Guy on your car - and yank it out for a hard look. Actually on a vehicle that old, I would probably just replace it once it was out.

Flush everything back to bare metal, add back the correct oil charge & vacuum.

B.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Edited: Sun April 05, 2009 at 9:44 PM by Automotive Air Conditioning Information Moderator

GM Tech on Sun April 05, 2009 9:22 PM User is offline

A simple forum search reveals the weirdness of a rotary vane compressor...you might want to consider these conceptions..

An example of rotary vane failure to generate pressures

Another example of rotary vanes failure to pump on recharging....

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Desp on Sun April 05, 2009 10:07 PM User is offline

I charged it using a standard manifold gauge set. The first time I tried to do it with the old compressor it actually took 30 oz. and the high side never went above 100 PSI. Using the new compressor which is working correctly, with 2 cans in the system it pulled a vacuum on the low and the high was around 100 PSI, not sure how it could be anything else, other than a blockage. I am going to take apart the system in the next couple days and inspect everything. I already bought a new drier to put in it, but I might need a new expansion valve. If it's blocked is it possible to clean them?

Desp on Sun April 05, 2009 10:09 PM User is offline

Quote
Originally posted by: GM Tech
those rotary vane pumps need to have a complete charge in them to get them pumping- seen it several times- slow to build high side pressures- I usually overcharge for awhile to get them going--- then ruduce the charge to spec...I highly doubt you have a blockage....

The clutch engaged and the compressor was spinning, the low side took 2 full cans and the pressure dropped to 0, until I revved it above 2000 rpm then it pulled a vacuum, wouldn't that mean it's pumping?

Chick on Sun April 05, 2009 10:35 PM User is offlineView users profile

That is usually a bad expansion valve, change it and follow bohica's advice to flush it clean..hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Desp on Mon April 06, 2009 8:29 AM User is offline

Quote
Originally posted by: Chick
That is usually a bad expansion valve, change it and follow bohica's advice to flush it clean..hope this helps..

Going to be doing that in the next couple days, thanks for everyone's help.

GM Tech on Mon April 06, 2009 9:09 AM User is offline

I'm here to tell you- throw out all common sense when dealing with rotary vans-- I had two Saturns that I replaced the compressors on- because they acted weird- low low suction, discharge low-- Put new pump on- same thing-- so I want to know what gives-- I want to see some high head pressures- so I overcharge- to get rid of that low suction- and finally the pump starts generating significant head pressures- 300psi- plus. Then I shut it off- recover enough refrigerant (the same amount as overcharged) and it starts performing normally- cooling good- something changed- either TXV opened or the compressor started pumping correctly.

Go ahead do your flush - good to know if something is blocking you-- but I am just sharing my experiences with rotary vanes..I wasted my money on replacement compressors- would have put the old ones back on- but lost the core in the exchange. Both cars are still running and cooling good- sure there may have been a blockage- but I doubt it- the old compressors were not trashed inside- a/c system failure was due to a low charge due to a leak- just that they went over the winter not pumping- and needed a kick start of sorts...but I was in a hurry and recommended new pumps-- and got the same results.....

Since then- I have made it my personal note- that a pump isn't pumping until it generates significant head pressure- regardless of suction pressure.

If the original poster's failure was due to a leak (how much refrigerant was recovered when it was first touched?) then that sends me down the above path. If all the refrigerant was present and compressor was trashed inside- then I agree- flushing for blockage is needed. The TXV may be stuck as well due to lack of use-- but I usually whaaaap those several times to get them unstuck- or use the extra charge to force them open...

Let the plot thicken and draw your own conclusions......



-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

TRB on Mon April 06, 2009 9:46 AM User is offlineView users profile

GMTech, did you add a specific amount of refrigerant when overcharging the systems. Be nice to try in our shop and see if we can achieve the same results.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

GM Tech on Mon April 06, 2009 12:09 PM User is offline

I just add and watch pressures- can always shut off the valves when I start seeing pressures rise- Usually up to a pound or a pound and a half...when you're pissed at a system- you tend do things you normally would not advise-- but hey it worked for me....

Had a newly installed TXV on an old Chrysler act similiar-- overcharged it to break it loose- never had problems after that...my MIL's car.

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Desp on Thu April 09, 2009 8:48 AM User is offline

Quote
Originally posted by: GM Tech
I just add and watch pressures- can always shut off the valves when I start seeing pressures rise- Usually up to a pound or a pound and a half...when you're pissed at a system- you tend do things you normally would not advise-- but hey it worked for me....



Had a newly installed TXV on an old Chrysler act similiar-- overcharged it to break it loose- never had problems after that...my MIL's car.

When I was messing with the original compressor, I overcharged it by 12 oz and I still had the exact same results, something else that was weird to me though, the high side never raised even after over charging it, maybe I needed more?

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