2nd Gen Non-Engine/Transmission a/c question

[Tractorat]

Can the a/c leak when the truck is just sitting there not being used ? I had an a/c service maybe a month or 2 ago. Seems like I was driving the truck a couple of times a week. When I last drove it about 2 weeks ago, the a/c was blowing cold. When I pointed my infra red thermometer at the back of the vent, I could read down as low as 16 and even 12 degrees. That was the last time I drove it. Well, I drove it this morning and it is not blowing cold at all. The compressor now clicks maybe every 7 to 10 seconds where it used to be once every 20 seconds. (but the tube under the hood is cold)



Any ideas ?

 

[Bob4x4]

The system is always under pressure,just lower when the compressor is not engaged.

 

[JKosten]

The most common leaks are from the schrader valves and the compressor seal as they are the only moving parts.

 

[JLandry]

It definitely sounds like the refrigerant has leaked out.

When you have it charged again, request that UV dye be added with the refrigerant so they can check for leaks using a UV light if this happens again.

As JKosten mentioned, slow leaks from the high and low pressure fill valves are common, but these leaks can be problematic for a mechanic to diagnose in one visit, even with UV dye in the system. This is because you'll always see the UV dye in the fill valves... it has to pass through them!

I've read (haven't tried it myself yet) that you can check for fill valve leaks after recharging the system by stretching small balloons completely over each fill valve and the letting it sit overnight or longer. If refrigerant is leaking, supposedly the balloon will gradually inflate.

Best regards,

John L.

 

[Tractorat]

When you have is charged again, request that UV dye be added with the refrigerant so they can check for leaks using a UV light if this happens again.

Thanks, yeh, they did add the dye when they did the service. They found a leaky valve and replaced it at the time. I'm going to take it back and have then wand it again. I just didnt think they would leak if the truck just sat there for a week. Or if you drove it w/o using the a/c or defrost.