Question before my repairman gets here?

I posted this over in alt.hvac but that was, apparently, an error on my part. <wince> They referred me over here. Hope someone with more knowledge than I (which is just about ANYONE!) can give me some guidance.
The story:
I noticed that, while my AC was blowing out cool (as opposed to warm) air, it didn't seem as cold as last summer. To test it, I put the thermostat down to 65 and left it for 24 hours. The outside temp was about 78 yesterday, and when I came home from work, the inside temp was about 75.
I called a repair place (don't know him, just pulled his number out of the yellow pages) and they said they could come tonight. Wonderful! He came, he checked the unit, said it was functioning properly, but needed freon. He put some in, came back inside the house, put a little thermometer on the vent, shook his head, went back out and put more in, and came back in (didn't test again), said he was done, I paid him, and he left.
I didn't look at or move the thermostat after he left. This morning, I'm a little warm, and go to turn down the thermostat, and it is down to 62, but the house is at about 73. I walk over to the vent, and warm air is coming out. :-( I called the repair place; they are coming out this afternoon. The lady on the phone said something about maybe a leak.
My question to more knowledgable people: does she mean a leak in whatever holds the freon? If so, should that have been checked before he put more in (to the tune of 140.00?). In other words, is there a way of checking that beforehand, or is it just a case of "If it comes back out again, there is a leak." I know absolutely nothing about this stuff.
Also, since they failed to diagnose the problem yesterday, will I still be charged for the service call?
Thank you for any help you can give me!
Sheila
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WhansaMi wrote:

You got some very good advice over there, and the guy(s?) who steered you away were actually civil, that isn't guaranteed by any means. Probably 'cause you're a lady, but anyway...
Quick recap: Old saying "If they're sick it's cause they're dying" from the horse racing world I believe, but it sort of applies to AC as well.
If they need charged, there is a leak, period. IS. As in: "service people who were here yesterday, WHY DID YOU NOT TELL ME there was a leak, and why did you not TRY TO FIX IT?"
FYI to you ar anyone else reading, this applies to car AC units as well. The AC is a "sealed system", if it never leaks, that Freon will last forever, they don't need "charged" for any reason, except if you HAVE A LEAK, of course. :-)
--
TP / Network Man __________________________________
If u want the races for free,
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Coincidentally I had some HVAC trouble yesterday. When the repairman come out, he found out the installer from his shop had left the two booklets for the owner and other junk inside.
I'm beginning to see why the NO YP and TV have so many lawyers. zemedelec
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They mean a leak in the pipes or coils that hold the Freon. You will probably be charged more, but you can always protest it. I would think it would be reasonable to pay for fixing the leak and the time spent finding it (or any other parts which may need replacement), but not for the second service call.
"WhansaMi" wrote in message

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AND you should definitely get a credit for the freon that was put into the leaking system. That was their dumb ass mistake and you should not be charged for it. Tell 'em to take it out of the first repairman's pay check!! He won't make that mistake again.

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You have the right idea, but the wrong approach.
Before turning on the A/C, note the ambient room temperature. Put the thermometer into the cold air duct and turn on the A/C. After approximately 5 minutes, the thermometer reading should be about xxx degrees cooler than the ambient room temperature. Sorry, can't remember exact numbers, but 25 degrees cooler seems to come to mind.
It's a quick way to see if something is drastically wrong.

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Actually I believe it is a 20 degree drop you are looking for if your unit is using standard home cooling refrigerant.

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