While driving on the freeway the A/C stopped blowing air. I turned off the A/C and the vent on and slowly air would start to come out again. Am I correct, is it freezing? How can I fix this? or what is it?

 

Sure sounds like it's freezing. Several things can cause this. I would first check to see if the compressor is cycling on and off. If it's not cycling off, it could cause this. Hooking up a set of gauges would be next order to see what the pressues are. Say much else at this point would just be guessing and a little more data would be helpful. I assume it all works normal at start up.

 

You might have to check the pressures in your system if it is low it will freeze the system and also see if your compresser is cyling I had this problem om a Grand AM where it was not cycling and it made the A/C freeze up.If your system is low you will have to check for leaks(usually you'll see some wet oily substance around a fitting with dust or dirt accumulating to it) if it leaks and you aren't sure haw to work on it have it serviced by an A/C Tech.(a set of gauges generaly will show you where you should be on your High and Low side of the A/C charge)

I hope this helps.
Thanks,Matt

 

Thanks guys, I guess I have to take the VETTE to an A/C shop.

 

If you don't have the gagues and the A/C knowledge the shop would be the best thing to do. But you can check your compressor to see if it is cycling. In some cars low freon will cause it to freeze but with my 94, if it gets to low it starts to take a long time to cool down and then it just does not cool any more.

 

Something blocking the flow of air over the evap. could cause this.Or running with the blower motor off for a while.Or a slight undercharge can cause a system to freeze back.

 

Now hear this....I turned the A/C on and turned the digital temp. to 70F. It worked fine, did not freeze. What the heck is wrong with this monster???

 

Checking pressures might give you some insight. If the system is working as designed, it isn't going to freeze up as the PCM is going to cut power to the compressor when the pressure is low enough to make ice (about 22.5 psi). It will also turn it off if it gets high enough to blow up - about 400 psi. If it isn't cutting off at the low threshold, it usually needs a new device - a low pressure switch - to get it working again. With a manifold gage set hooked up, you can see just what it's doing by disconnecting the blower motor with the controls on max. The low side pressure will drop and the compressor should shut off at 22.5 psi. A gage set is about $80. At this time Year, some shops will test it for free or Pep Boys advertises their $29.95 performance checkup in the Sunday Funnies every week (at least out here).

 

After another cup of coffee, I just remembered an anomaly that's seemingly common on late model GM's (I had it on my truck and couple of other members have posted it about their Vettes): The connector at the low pressure switch becomes intermittent so the compressor disengages or won't engage, until it connects again. Normally, anything from '90 up is going to shut down permanently if the pressure is too low (or too high) and won't restart until memory is removed from the device controlling the system; ie, you're going to have disconnect and reconnect the battery - and that isn't happening with your Vette.

The PCM monitors system charge by looking at how often the low pressure switch opens and closes and by making sure the high pressure switch signals an increase in pressure once the compressor engages. Too much cycling (on and off of the compressor) and/or no pressure rise indicates a problem so things are shut down until you fix it. However, as far as the built in diagnostics are concerned, a low pressure switch that simply opens and stays open for awhile, doesn't indicate anything and when the connection is re-established, everything works again. So, I recommend you test that connection by wriggling it around or the next time it shuts off, simply remove the connector and reconnect it. If that gets it going again, you need a new connector.

 

Thanks for the advice.

 

I bet it's slightly undercharged,you need to put some gauges on it,to see high and low side pressures.

 

You all were correct. It was the cycle switch.

Total with parts and labor: $103.92
Driving with A/C at 100 F: Priceless

Thaks for the Help

 

.......OUCH!......but glad ya got it fixed....