Freon leaking in chassis AC

tompla wrote:
I am having to recharge my chassis AC every year. My class A MH has been checked for leaks using the dye/black light method and the "sniffing method". No leaks were found. WE live in a cold winter climate. The technician tells me that the leak is very slow and will be very hard to detect. He believes that temperature of the Freon determines when the system will leak. When the Freon is warm, it maintains pressure in the system. There is some type of little valve that seals the line at some place in the system due to the maintained pressure. When the Freon is cold due to winter storage in an unheated shed, it does not maintain pressure and hence the little valve does not seal tight and the system leaks. Have any of you heard of this? The tech feels it is better to spend $50+ to recharge each year than go any further in solving the issue. What the thoughts of you who have experienced this.

How old is the system? I'm assuming you have an R-134 system. (1995 and later) R-134 is a smaller molecule than the older R-12 refrigerant. It can seep out through O rings that have gotten dry or just shrunk from age. I've also seen it seep from the seals on a compressor as well as the low pressure switch assembly. $50 doesn't sound too bad as a grenade (12 oz can) of R-134 can run a good $15-20. You will probably spend several hundred dollars fixing the leak and even then you may not find that one little O ring that's seeping.