1990 Cougar, AC is cycling

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  #1  
Old 06-19-07, 07:17 AM
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1990 Cougar, AC is cycling

I have 1990 Merc Cougar 3,8L, auto. My ac was rebuild and switched over for 130 freon a few years ago. Now my AC stops blowing cold air but I still hear motor running and after a minute or so it starts for a little again and then stops without motor shutting off. What does it mean? Last time I checked I had full charge of freon.
Thanks. Irina
 
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Old 06-19-07, 07:39 AM
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I would check the charge again, it may be low. Also some vehicles (like my '94 Chevy wrecker) have what is essentially a thermostat that senses the temperature on or near the evaporator core in order to cycle the system and prevent icing. The one on my truck has a small set-screw that you can use to adjust the cycling interval. Before you get into that (if it's even so equipped), check the charge.
 
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Old 06-19-07, 08:20 PM
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the only reson I've ever known for that is being low on freon, other than that, I haven't a clue. might take it in and have it checked. They should be able to do that for nothing.
 
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Old 06-20-07, 05:44 PM
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I took it in. They said the pressure is too high. They recharged it and AC is not cycling as much and for too long. It's still not cold enough in the middle of the day, but better. They found a small leak with the dye and said that there could be clog in the line and that I might want to replace the line.
What do you guys think about it? Sounds somewhat contradicting to me. If there is a leak how can pressure be too high in the sistem? BTW, ever since the conversion AC was never "too cold".
Thanks. Irina.
 
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Old 06-21-07, 05:28 AM
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Was this a general repair shop or an ac shop? I'm thinking about the only place you could have a "clog" would be the expansion valve.

Here's a good primer on ac systems:

http://www.id-usa.com/how_to_ac.asp

R134 is not as good a refrigerant as R-12 was as you've discovered, but a properly functioning system should give you all the cool air you need.
 
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Old 06-21-07, 05:39 AM
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It was general repair shop and they were talking about some line and put "evaporator valve" in the recommended service.
 
  #7  
Old 06-21-07, 01:02 PM
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Hey Tow...........She probably has a compressor starting to come apart..........Little aluminum particles "float" through the system and eventually clog the orifice tube..........which in this case (and many other Fords) is a "liquid line"...........not just an "O" tube
When the compressor kicks...........the low side gets sucked below 20 PSI and the low pressure switch shuts down the system...........Once the pressure equalize the joker turns back on ........and the process begins again
 
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Old 06-21-07, 01:39 PM
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I try not to get too deep into ac talk, makes my head hurt. Expansion valve and orifice tube are in somewhat the same category of function, I think, and both have small passages that can get obstructed.
 
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