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Discussion Starter · #1 ·
Just joined the site because it has been great in helping me change out the A/C clutch on my 1998 Taurus GL sedan. However, now I have a question about normal operation of the A/C system.

The clutch turns on for about 4 or 5 seconds at a time, then off for 30 seconds or more, and then on again for 4 or 5 seconds. It was doing this even before the clutch blew up. The A/C is still blowing cold, but I am wondering if this is normal for the A/C system. I am almost tempted to just leave it be since everything is working, but am a little worried that something like this might lead to premature A/C clutch failure.
 

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Discussion Starter · #3 ·
Hows the freon level?
I don't know the answer to that. Right now, I am researching to figure out how to measure the high and low pressure in the system. Haven't quite figured it out, but will do some more research tonight and head to the parts store tomorrow to buy the gauges I need to do so.

With that said, the A/C is blowing really cold.
 

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No, it is not normal. On should be longer. Frequent switching on/off wears both clurch and compressor.

When AC doesn't run, freon vapor pressure is about 100 psi. When AC runs, suction side pressure falls to, say 40 psi. If freon is low, it can fall further and trigger low freon switch. 'sheila' must be suspecting low freon. Check the pressure. Of if you have not done anything with AC for years, freon is most likely low.
 

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Maybe it was over-charged? Needs to be checked with good pressure gages. I would avoid using it until then, becouse you can damage the compressor.
 

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Discussion Starter · #8 · (Edited)
Buy a A/C gauge from parts store. Connect it to the LOW pressure side with engine off. Then you start the engine ans A/C - I suspect you have low pressure (need to add more freon). But only measurement can tell exactly.
How to Recharge the Air Conditioner in a Car - wikiHow
Thanks for all the replies guys.

I am guessing that I am low on refrigerant. The system has never had anything done to it the 13 years I have owned the car. Just replaced the A/C clutch so I'll check the refrigerant pressure tomorrow to make sure it is right.

JMan, the internet is great. 20 years ago I would have been scared to death to try anything like this. Between the Interdynamics website with its how to videos and this chatboard, I have a clue as to what the issue is and how to fix it. Tomorrow, I am going to check the pressure and charge the system if need be.

One question that I have not been able to figure out is whether I have to add oil/refrigerant to the system or just refrigerant. Anybody know how I can figure that out?

Edit to add: I think I just figured out the oil issue too. Since I haven't replaced any of the actual system parts like the compressor, evaporator, drier, etc., then I don't really need to add oil. Just need to check the refrigerant and charge it if it is low.
 

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Discussion Starter · #9 ·
Added 34 oz. of refrigerant to the system and the compressor was running almost the entire time that the system was on max A/C with the fan full blast. Prior to that, I could see the pressure drop dramatically in the system whenever the compressor came on. It would shut off whenever it dropped too low, which was almost right away. As I put more and more R-134a in the system, the longer the clutch stayed engaged. Thing is, I think I have a leak in the system somewhere. Five hours later and the clutch isn't staying engaged quite as long.

I truly hate A/C and heating systems. They are way too expensive to fix and way too complicated to fix. I guess I am going to have to do some more reading up on this issue to try and find where the leak is in the system, and then on how to fix the leak.
 

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The clutch is supposed to cycle, just not rapidly. 34 oz sounds like it's way too much. I'm pretty sure that's right around the max total that should be in the system, definitely too much to be added on top of what was in there, since the system had to have some in it already.

I don't know if anyone has access to them (they may have been posted in some other topic a long time ago), but Ford has these charts that show you how much ON time and OFF time there should be, and it helps you diagnose issues based on system pressure and on/off time.
 

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Total system capacity is 2lbs. 2oz. (34ozs.). Definitely was overcharged unless the system was empty. Total PAG#46 oil capacity (divided amongst the compressor, evaporator, condenser and accumulator is 7ozs. Those cycle charts Dave mentioned may be contained in an old thread here somewhere? Might do a search here (click search at the top of this page) or google it. They are contained in the Haynes Techbook of Automotive Heating and Air Conditioning, but too many to print here. Recommended purchase if youre going to perform some of your own ac work. Available in paperback at most auto part stores for about $20. Good luck.
 
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