Guys I took out my evaporator today to clean it since it has never really been cold like it used to be, only get to 50 on the center vents. Originally the compressor went out I replaced it and the drier. But I think I should have replaced the expansion valve also. So this time I would like to get some experts opinion on this. I plan on replacing the Expansion valve this time, but cant decided what to do and far as freon goes. I searched but only found people debating and both sides saying theres was better.

Thanks for the help

no need to stay with r12 unless you just have some laying around.follow proper steps and it should work fine.use vacume pump,charge to 80% volume,get the old oil out. this site may be helpful. <a href="tohttp://www.honeywell.com/sites/sm/chemicals/genetron/mobileac3_cat19194b8-fb3e3e4705-3e3e4447ab3472a0c2a5e5fdc1e6517d_HTM19194b8-fb3e4258f1-3e3e4447ab3472a0c2a5e5fdc1e6517d.htm" target="_blank">tohttp://www.honeywell.com/sites/sm/chemicals/genetron/mobileac3_cat19194b8-fb3e3e4705-3e3e4447ab3472a0c2a5e5fdc1e6517d_HTM19194b8-fb3e4258f1-3e3e4447ab3472a0c2a5e5fdc1e6517d.htm</a>

some of the stuff imported and being sold as r 12 is mostly hydrocarbons(propane)so watch what you buy if you do go with r12

I have a pretty good guide for changing over to 134a,but I dont know how to post it here.anybody wants it can send me an email and Ill send it to you.It is mainly for stationary equipment ,but the steps should be very close. ckrug4@aol.com

This may be a dumb question but is it mandatory that I pull a vacuumm on the system? Is there a way to just add 134a and purge the system or air? I dont have acces to a vaccum pump or any guages.

Thanks

Never Mind I have found a vaccum pump, and guages if there open tomorrow. Now If i only new how to read the guages.

Vacuum Pump

Thanks

Thats not a good way to vacuum the system.Better than nothing but not by much.You need 4cfm for 45 minutes to remove most of oil and moisture,the ability to inject oil.Pay a shop to recover your r12 and vacuum down the system.Also its illegal to vent the r12.

I thought about adding in my original post "dont even consider the HF vac pump".It will not achieve a low enough level of vacume,waste of money.If you try to purge rather than evacuate you will end up with intermitant cooling problems.do it right or wait till you can,otherwise you will do it several times and end up paying someone else to do it or living with an ac that dont work.I would suggest you study on it some more before you do it.

to read the gauges : above zero is positive pres,below zero is a vac. You need to get the system to around the 30" mark and hold it there for at least an hour.Time is not so important as the level of vac. you achieve,but if you dont have a rather pricey micron gauge then you run it for an hour and hope in that time you get it down to 250-500 micron range.The standard gauges dont read in the required vac range , which is lower than 30"
I know I have been rambling here ,but I repeat DONT WASTE YOUR MONEY ON THE H.F. pnuematic vacume pump.you might as well suck it out with a straw.
good luck

with all due respect, have you actually tried the Harbor Freight venturi vacuum pump?

what is the problem with it exactly? does it not pull low enough? I thought most evac specs were to pull and hold at 30"

Have not tried it, but it specs at 28.3" max. vacuum. Plus, you'll need to be running your air compressor @ 4+ CFM for a half hour or more, might be something to consider as well.

no it does not pull a deep vacume.proper evac of an ac system is 250-500 microns.1000 microns will do if in a hurry.but 28" is not even close.you will not get all the noncondensibles out with a 28" vacume.moisture can mix with oil,especialy mineral oil (kinda like it does with brake fluid) and it will not b oil out at high vac. levels.
No I have not tried one and dont think I would unless there was no other option.I see vacume pumps in pawn shops for 40-100 bucks,thats a realprofesional type pump rated at 4-8 cfm.
Also the HF vac pump I saw said it was rated at 14 " vac.Either way 14-28" is not low enough to get moisture and noncondensibles out of the system.I have seen what lack of vac can do to systems in the long run so Im not going to try it on my stuff
On the other hand if you use it and you like it and it suits your needs more power to you. <img src="/forums/images/graemlins/cheers.gif" alt="" />