Accumulator Freezing Over

[Quarterwave]

Hi all,

I'm the new owner of a 1996 Astro - 4.3 L auto - and are having a problem with my AC. After having it on for around 30 mins, the AC air coming from the vents decreases rapidly, so I checked all of the air vacuum hoses for a leak, and they seem to be ok.

The abnormal thing that caught my eye, was that the AC accumulator was completely covered in white ice - is this normal ? As I've never noticed it on my other cars in the past.... if so, could this be the source of my AC problem ?

FWEIW, whenever I start the van the next day, the AC is back to working as it should....

One last thing - I've noticed that when set to MAX AC, it takes less time for the problem to occur....

Thanks in advance for any help !

[Big_kid]

Check the charge, you might be low on refrigerant.

[gtkane]

The low pressure cycling switch is stuck closed.
Change it.(and you don't have to suck the refrigerant out to do it.)

[Big_kid]

Makes sense!

[Quarterwave]

Thanks GT Kane - can you pls adv. how I can do that - ie : where is the switch located ? Is it on the compressor ? Is there any pressure in this part of the system that I need to know about ?

Also - do you think that this could be a source of a battery-charge draining problem that I have been having ? (even when the van is turned off ?)

Thanks again for your help.

[gtkane]

It won't cause a battery drain issue-sorry!

It is located on the accumulator(aluminum can-looking thing), and has 2 wires going to it. Just unscrew it with a 9/16 wrench. No refrigerant will escape.

[Quarterwave]

Just a follow up on this one. After not being able to solve this problem, I took the van to my local auto electrician, where he diagnosed a problem with the AC relay. It seems that I was pulling the correct one that corresponded with the diagram on the inside of the fuse box, but after looking @ the schematic, it was the wrong relay to check.

So.... it seems that the dealer I bought it from had opened the relay and put in a thin, flat piece of wire near the bottom of it, which bypassed it's "turn off" function. As soon as the electrician pulled the piece of metal out, and turned the HVAC control in the cabin to "OFF", the compressor stopped spinning and the ice went with it.

After replacing the relay with a new one, the compressor started cycling as it should. We were unable to diagnose why the dealer would do that to the relay, as again, the AC is working as it should (at least for now), but I will continue to keep an eye on it for a while.

Thanks again for all of the responses to my post.

[Big_kid]

Good find!
Thanks for the update.