a/c charge

[fsteyer]

Hi-
I just replaced my leaking condenser. I charged the system and the a/c workes but I have to wonder:
1. there has to be air in the circuit
2. so how does one proberly refill/charge an a/c system from scratch?


Thanks

[onewhippedpuppy]

You have to vacuum it down to remove all of the air, then fill it with freon and oil. Has to be done by a pro, unless you want to buy some pricey equipment.

[fsteyer]

thanks -
in the meantime is it just not working at optimum or is is actually damaging my system?
thanks

[onewhippedpuppy]

If you had the system open to atm, running it now isn't ideal. If you lost your system oil you're damaging the seals running it as is. I would go get it vacuumed down and re-filled, that's far cheaper than replacing a compressor. How bad it is I really don't know, but why take a chance?

[joshua43214]

If you charged the system with air in it, you will ruin the compressor and the expansion valve eventualy. Take it to a shop that can fix it properly. Do not use it until then. You will need a new receiver dryer now too since you probably just ruined your old one.

Don't let any one tell you differently. AC charging is not a DIY thing unless you have the equipment to do it properly.

[winfred]

when i service a system or convert it to r134 i drain the compressor and refill with the correct amount of oil usually 5-6 oz depending on the car, i like ester oil as it will do r12 or r134 and is compatable with copper (pag oil and the copper that can be in older cars don't really mix) blow the lines clear with air or flush if the compressor took a dump or it's a contaminated system, replace the drier and expansion valve and clean the crap off of the evaporator and out of the box while i am doing the valve, then vac the system for around 45 minutes, turn the compressor over by hand a few times to clear the oil from the cylinders and charge 4.2# r12 or 3.4# r134 on a e34

[SchnellE34]

noted, thanks gents

[t_marat]

Is this the dryer?
http://cgi.ebay.com/ebaymotors/89-95-BMW-525-528-E34-AC-HOUSES-FITTING-LINE-DRYER-PIPE_W0QQcmdZViewItemQQcategoryZ33544QQitemZ806914 2924QQrdZ1QQsspagenameZWDVW

No sense in buying it as it had also contact with air?

[SchnellE34]

its the big black thing in the bottom right corner, close up it looks like this (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=6630819814&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1)

[winfred]

dat's de one, you don't want a used drier anymore then you want a used fuel or oil filter


its the big black thing in the bottom right corner, close up it looks like this (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=6630819814&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1)

[Chris'91'525i]

Hi-
I just replaced my leaking condenser. I charged the system and the a/c workes but I have to wonder:
1. there has to be air in the circuit
2. so how does one proberly refill/charge an a/c system from scratch?
Thanks

I would stop using your AC till it is fixed correctly.
Air and moisture in the system will turn into real nasty acids when mixed with refrigerants. Or moisture can freeze up componets.

I worked with one guy who was a real stickler when evacuating the AC system, after all leaks were verified and fixed he purged and pressure tested system with Nitrogen.
He would heat the AC system componets up around 110 Deg. F , To help draw out more moisture, solvents from the system, when pulling Vac.
When system is being evacuated ,the vacuum causes any moisture to boil and turn to vapor and get sucked out of system.
Then would purge the system with R12 vapor(or what ever was needed) a couple times, and do a final deeep evacuation for 30-40 Min.
Probably over kill, but done to the **** !!

[fsteyer]

thanks for all replys.
Now I understand why they charge $100 to do it.

[fsteyer]

I had it done .... they used one of those automated machines. Sucks the system dry in 20 minutes, then charges it. Afterwards they said that I had high pressure on the return side caused by some kind of "blockage". What's the deal with that though, the ac works fine. Did theyt just want more work?
thanks ....

[joshua43214]

High pressure on the low side is an indicator of a bad expansion valve commonly.

If the AC gets nice and cold, and the person who worked on it was not very knowledgable, I would not worry about it. The high and low side pressures are dependant on ambiant temperature, interior temperature, blower fan speed, air movement through the condensor and RPM. Its not hard to read gauges, it just takes experience. Expansion valve systems can run higher low side pressures at times compared to orifice systems like what Chevy uses.

[Chris'91'525i]

I had it done .... they used one of those automated machines. Sucks the system dry in 20 minutes, then charges it. Afterwards they said that I had high pressure on the return side caused by some kind of "blockage". What's the deal with that though, the ac works fine. Did theyt just want more work?
thanks ....

Did you change the receiver drier too ?
A 20 Min. evacuation sounds kind of short....
Maybe the expansion valve is getting slightly iced up...... If you got a new receiver drier it should store a small amount of moisture in the system eventually....
If it's blowing in the low 40's (F) I would'nt sweat it.
(what a lame pun :) !!!!!

[ThoreauHD]

Winfred, your signature creeps me out man... Really.. Creeps me out.

[fsteyer]

Thanks ... I had it done at a Midas shop, and the guy wasn't an ac specialist or anything like that. He, more or less, just ran the machine. What temp should I expect to see at the output register run the ac full blast with recycle air on.
thanks ....

[joshua43214]

Ignore anything a Midas "tech" says. With recirc on and at high idle, it should be cold enough to make your hand ache when held infront of the vents. Low40's or high 30's, I forget what temp the system shuts off at.

[fsteyer]

Thanks ... I checked the output temp at the dash register with a digital thermometer. The low reading was 43 degrees. So I guess the system must be OK. Thanks again for your input, it set my mind at ease.