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Cleaning the A/C expansion valve


74Adam

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Ok, with my dash out for the time being I am taking the opportunity to install A/C. I'm using a 75 280 unit so that it will be factory (stock switches, evaporator under the dash...ect). Anyway, my evaporator and housing looks pretty good, but I found out that sometimes the expansion valves (in general) can get dirty or corroded and not work very well or even fail. Anyway, I don't even know if this is something to worry about, but I thought it might not be a bad idea to unscrew the hard lines and spray some B-12 in there. Bad idea/good idea....any thoughts?

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It shouldn't hurt anything. I'd use brake cleaner instead. Leaves less stuff behind. If it were me though, I'd just replace it and not take any chances. They're not that expensive and there are other things that can go wrong with them that you can't see just by looking.

 

Most important thing you can do is insure all the parts are very clean on the inside. One grain of sand size partical can plug the expansion valve.

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Well, I tested it last night, and it's working fine. Did the hot water/freezer trick.

 

A different question: What should you put on the fitting threads to seal them? Something analagous to pipe dope or teflon tape when putting gas lines together.

thanks again

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Sealant on the threads of flare fittings is useless. If you want to, put a small film of sealant on the flare's mating surfaces being carefull not to get even the smallest amount inside. I use a product called "Leak Lock". It is specificly for sealing refrigarant fittings and is designed for the temperatures, oils, and refrigarants that are in A/C systems. The stuff is great. I've never had a fitting leak when I've used it. You will probably have to go to a HVAC supply house to get it. You can buy it in a small four ounce tube for a few dollars. If that's all you're getting and throw cash on the counter I'm sure no one will give you a hard time.

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