A/C issue
Thread Starter
Melting Slicks
Joined: Sep 2002
Posts: 2,329
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A/C issue
When a/c is on and car is at idle it is cold. It remains cold going down the highway for about an hour of steady driving. At this time the fan seems to labor somewhat and airflow reduces. The air that comes out at this time is markedly warmer but still moderately cool. Let car sit for a while and the whole cycles starts over. What's up?
Burning Brakes
Joined: Dec 2003
Posts: 1,066
Likes: 9
From: Eddy Texas
Sounds like your evaporator is icing up, which in turn blocks airflow. Could be caused by dirty or clogged fins on your evap, low 134a charge, or a partially restricted orifice tube. Get the 134a charge checked accurately, and that will rule out 2 out of the 3. If your orifice tube has got some foriegn material in it, you will see very low suction press combined with a high discharge press, as the tube would be restricting the flow of 134a too much. If you are low on ref, the temp of the evap coil will be too cold and any humidity on it can start to build up in the form of ice and eventually cover the coil, blocking airflow. If the surface of the coil is dirty, it can also reduce airflow which lowers coil temp and starts the process that way. One other thing would be the fan motor, failing and slowing to a point where ice begins to form. Your best bet is to get the 134a charge checked accurately. Here's a good link with directions, if you need it.
http://forums.corvetteforum.com/show...ghlight=ac+101
http://forums.corvetteforum.com/show...ghlight=ac+101
Last edited by c5streak; Sep 21, 2008 at 08:12 PM.
