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won't take charge

tndave on Thu May 08, 2008 9:53 PM User is offline

Model: Sable
Engine Size: 3.0
Refrigerant Type: 134
Ambient Temp: 75

I haven’t worked on cars for a long time and when I did it for a living I wasn’t exactly an AC expert, but usually managed to get things going. I am now a dealer and will be doing most of the work on the cars myself, at least for now. So I found this forum and decided to ask questions before doing anything.

I just bought this Sable so I don’t know the history. Here’s what I do know…ac don’t blow cold, compressor kicks on for a couple of seconds and then off. No grinding or clunking noises. I figured low charge, so I connected my gauges and the high was about 30 and would go up to about 50 when the compressor was on. The low was about 50 and would go down to about 35 when the compressor was on. So I tried to put a can of 134 in and it wouldn’t take it. With the valve open the low was about 90 (can pressure) and the high never changed. When I turned the car off there was no hissing sounds coming from the compressor. With the car turned off the low is about 60 and the high 25.

I’m thinking that the orifice screen may be clogged and the accumulator/dryer probably needs replaced. Then pull vacuum and charge. Does that sound logical or could it be a compressor problem. I am having to do a lot of other work on this car, so I would rather not replace the compressor unless I have to.

Thanks,
DD


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I think I’m having amnesia and daja vu at the same time…I think I’ve forgotten this before!!

Edited: Thu May 08, 2008 at 9:56 PM by tndave

brickmason on Fri May 09, 2008 12:07 AM User is offline

What year model is it. May be a bad cycling switch.

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Just another brick in the wall

Had a little mule I fed him castor oil and every time he jumped the fence he fertilized the soil

tndave on Fri May 09, 2008 7:22 AM User is offline

Sorry, there was a form that I filled out, but for some reason all of the info was not displayed.

It's a 2001 Mercury Sable LS, 3.0 V6. I was a service tech for a few years, but that was over 20 years ago and I don't even have a manual for this car.

Thanks,
DD

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I think I’m having amnesia and daja vu at the same time…I think I’ve forgotten this before!!

Chick on Fri May 09, 2008 10:22 AM User is offlineView users profile

Since you don't know anything about the system, I would evacuate, pull a long deep vacuum and recharge the system amount back into the vacuum. Make sure your gages are depressing the shrader valves properly. Once the system is charged, the pressures will tell you what needs to be done, IF anything...You can jump the cycling switch (two wire switch on low side) if needed to keep the compressor running to pull the charge in.Usually not needed though when starting from a vacuum..Hope this helps.

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

tndave on Wed May 14, 2008 10:49 AM User is offline

Ok, finally getting back to this car. I haven't evacuated yet, but jumped the low switch and it went to about -10 on the low side so I tried to put some freon in and it took a little, but wouldn't take a whole can. Now with the compressor on and the valve to the can closed it is about +7 on the low and about 90 on the high and the high pulses about 5 lbs, like a heartbeat. It's blowing cold and the compressor is quiet.

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I think I’m having amnesia and daja vu at the same time…I think I’ve forgotten this before!!

Edited: Wed May 14, 2008 at 10:50 AM by tndave

bearing01 on Wed May 14, 2008 11:17 AM User is offline

so,
you're saying before
P_Low = 50psig,static and 35psig, running.
P_high = 30psig, static and 50psig, running.
Is this right? Sounds weird.

now you jumper the low pressure switch and P_Low goes to -10psig? After the system settles you got P_Low = 7psig and P_high = 90psig? And the high side gauge flickers...

Sounds to me like a restriction and/or moisture in the system that's freezing. See if any of your lines are cold and there's any point where you got frost buildup. That's where your restriction is. I'm guessing a plugged orfice tube and/or air+moisture in the system. Maybe time to replace that O/T and pull a deep vacuum.

mk378 on Wed May 14, 2008 11:58 AM User is offline

It's still undercharged. It should pull refrigerant out of the can rapidly under these conditions. You have a restriction in the charging setup. Probably your low side hose coupler is not opening the shrader valve on the car fully.

It's better not to jump the cycling switch for charging purposes. Running the compressor constantly while undercharged is not good for it.

tndave on Wed May 14, 2008 8:21 PM User is offline

You were right. The needle (or whatever you call it) on the shrader valve was bent over to one side. I figured it was clogged up from the start, but didn't think about the shrader valve being the culprit since I was getting a pressure reading on the low gauge.

I got it to take two cans...with the switch plugged in. Now low is abt 27 and high is about 135 and the compressor cycles as it should. The outside temp was about 72. I can't find my vent thermometer, but it was cold. I'll check it again in a few days and see if it has leaked back down, if not I guess I'll see if it will take another can.

Thanks!!
DD

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I think I’m having amnesia and daja vu at the same time…I think I’ve forgotten this before!!

Chick on Wed May 14, 2008 8:32 PM User is offlineView users profile

You need to have the full charge in it, which I believe is 34 ounces, should be a tag under the hood, running it with a low charge can damage the compressor. I suggest you either recover change the shrader valve and vac/charge the right amount back in, or if you did that, you have 24 ounces in ( 2-12 ounce cans?), add the rest as soon as possible. The oil travels with the refrigerant. Low charge=poor oil circulation and compressor damage will follow..Hope this helps.

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

tndave on Wed May 14, 2008 8:39 PM User is offline

Ok I will look and put some more in tomorrow. There is going to be a one day sale at a local parts store. $39.95 for a case of 12 cans, so I plan to stock up.

Thanks!!
DD

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I think I’m having amnesia and daja vu at the same time…I think I’ve forgotten this before!!

Chick on Wed May 14, 2008 8:55 PM User is offlineView users profile

30 pounder are going for $76.00 by me, cans are always more expensive, but you would need a good Scale but if you do any amount of ac work, the scale, good gauges and 30 pound tanks are a must, and cheaper in the long run..Have a birthday coming up?? Drop some hints to the wife and kids... Good luck and let us know how it turns out with the "FULL" charge in it, and remember, it will cycle more when cold out, much less when hot and humid.. Hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

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