Chrysler Repair: A/C, dodge shadow, outgoing lines

Question
Hey Roland:

Thanks for the info.  I will take my Shadow in tomorrow morning to get that looked at.  I will let you know what the synopsis and outcome will be.  I have another question:  Why does the compressor comes on when you use the defrost?  Even in the winter time when you have the climate control on hot, the compressor comes on.  Am I using refrigerant when I use the defrost in the winter time?

Thanks
-K-------------------------
Followup To
Question -
I am having a problem with my A/C in my Dodge Shadow. I don't really know if it's a problem or not, it might just needs freon. It is not getting cold at all. Is there a way to tell if the compressor malfunctioning or not. I was told that the compressor is belt driven. Is my compressor always on? In my Camaro, the compressor is always being turned by the serpentine belt, but the front of the compressor doesn't spin until I turn the a/c on and it gets cold.

My Shadow was bought at an auction, so I dont know anything about the a/c maintanence. I will take it in, but I just want to "eyeball" a few things before I do.

Thanks

Answer -
Hi Kevin,
The Shadow should behave the way the Camaro does. If the front of the compressor doesn't turn when you ask for AC then either the system is low on refrigerant due to a leak, or the clutch on the compressor is not being energized or the clutch is bad.  The pressure safety switch will prevent the clutch from engaging when the system pressure gets too low so that is a common sign that refrigerant is needed. However, if it is not that low, then the clutch can engage and seem to be o.k., but the system pressure is below normal so you won't get much if any cooling (see if there is any temperature difference between the incoming and outgoing lines on the compressor). Were there a temp difference, if you looked thru the sight glass on the filter drier assembly located nearby along one of the two lines, you would see bubbles which means the system is nearly empty but not so far as to turn off the compressor due to low pressure. If you don't see bubbles then the system is empty.
A normal condition is: the compressor is engaged (assuming that you asked for AC or defrost position), there is a big difference in temperture between the two hoses, and the sight glass is clear of bubbles. Be careful when touching the hoses they can be very hot and very cold, respectively when the system is working right.
Usually loss of refrigerant is the problem, though the clutch or the compressor can also fail.
Roland  

Answer
Hi Kevin,
The reason for the compressor for defrost mode is that the treated cold air is drier than warm air (or has less moisture content than if you hit it with warm air because the AC condensor removes some of the moisture in the air) so when it hits the windshield it won't condense water on the cold surface the way uncooled air does. Good luck at the shop today.
Roland