Posted by OzHeat on June 18, 19101 at 08:23:16: via: or 63.34.221.29
In Reply to: Re: window unit/vacuum pump posted by Chris on June 18, 19101 at 07:37:58:
You say you have an Emerson... Emerson only ever produced reciprocating compressors to my knoledge
Compressors from window A/C units are invariably reciprocating piston compressors. These recipocating comps make a clunking noise if shook hard (comp ass. hitting the housing) and look short and squat with the inlet and outlet on the side. Best vac pressure you can hope to get from one of these is around 27"Hg.
The best comps are salvaged from >2Hp window A/C units eg. whirlpool, westinghouse and fujitsu. These units contain a rotary compressors which work essentially as a retail A/C vacuum pump except they are only single stage. These look tall and slender, have the inlet to the bottom/side and the exhaust at the top. The best vac pressure you can gain from one of these is about 29"Hg.
I have made several vac pumps for various people mainly for physics and moulding purposes. If you want to use it for evacuating an A/C system you would atleast need 3 recipicating comps in series with each other or 2 rotary comps in series to reach 29.5"Hg necessary to boil off water vapour.
One word of warning.... don't allow them to get too hot as they have pressure relief plugs in them and will melt if comp gets too hot rendering the max pressure to about 2/3 of the original pressure.