hey orich...been thinking about the whole charging using the gas vs. liquid thing....if you use the gas from the can of freon and not the liquid part of it... doesn't that totally mess up the whole site glass purpose? I mean, what are you going to see in the site glass without the liquid?? and why would their be liquid in the can if you weren't going to use it? sorry if this is a "dumb question" just trying to understand.
thanks,

 

With all of the replacement out there. They are all Blend Gases (Freeze12, 134a), not like R12 being of 1 molectular (stable) chain. These blends have a tendency to segerate, and due to denesty the lighter is on top. So adding from the liquid they are still some what 1, if gas many. This is where doing a repair most techs will recover what there and use new. You do not loose all of the componets of the ref at the same rate if a blend gas. But with R12 you always add gas, unless you were doing the initial charge with the system off. Adding liquid to the suction side can damage a compressor (piston type). They are design to pump gas, not liquid.

As you said you added oil. This is the reason I never weight freon in. If a loss or excess in oil will change the charge.

 

Because the TXV can increase or decrease refrigerant flow according to load, it can raise or lower the amount of energy used by the compressor. Another benefit is that it can control the temperature of the compressor and keep it in a closer range through a wide load variance. Both of these are great benefits for energy consumption and compressor life. Also, the 100% shut-off valve can increase SEER by up to .50 because the liquid line is pressurized and ready to supply liquid to the valve the moment the compressor starts.

 

The only site glass used for charging is the one in the liquid line before the expansion valve. The site glass on gage sets are for 134, which is a blend ref, so you must use it to make sure you are adding from the liquid side of the can. If you converted a system you do a static charge with liquid to both sides (S & D) while it is not running. Then fine tune/adj with liquid to the suc, but you must add this very slowly to keep from damaging the compressor.

If you add liquid to a piston compressor you can brake a connecting rod, damage a valve or piston. Gases are compressable liquid is not. Example: Your ac comp take 30 psi gas and compresses it to 190. If this was liquid the pressure could be >1000psi. things break at the pressure.

 

Aw yep sorry well this does change things a bit for the STV Low side (10-20lbs by compressor) High side 120-180lbs for the norm. Sight glass should be clear for the norm, Liquid or oil streaks=a lack of freon for the norm. If you have a fan like a box type for the home. Place it in front of grille pushing air through the comdensor will also help.. When putting in freon Gas it helps speed up the flow to place the freon-can into some warm water like in a coffee can. Adding the freon-Gas take maybe 25 minutes+-so hang in here. We do cheat abit by shaking the can some what down ward before placing it back in more warm water.Remember to Bleed the freon line each time you add a new can to your charging hose a the manifold like i said before to do..hope this helps so what..
my 2cents
orich

 

thanks guys...you've helped greatly....my brother is coming over tonight and were going to go thru all these posts...and then try to "fix" the problem. appreciate all the info...and will post back when were done...hopefully with a "fixed" A/C.
david

 

so last night we started to work on it...checked out the pressures...not much had changed....low side dropped to about 36 (from 40 after about a week)...we figure most of the leak is from the valve to the compressor on the high side. We have the part and were going to change it, but got caught up in testing out some of the other things you guys had mentioned. When we ended up breaking the old turn handle off the heater valve...so we had to go get one and replace it. the temp at the vent didn't see any real significant differnce in shutting the valve off or leaving it open...which makes me think that has nothing to do with our problem. took the piece of foam and the remaining black tape off the TXV that we had wrapped back around it and it didn't seem to effect anything either. The sighglass shows fluid moving constantly thru the glass. we're going to take it to my brother's dad's house tonight for a few more test before we evacuate the system and change the high side valve to the compressor that is leaking...everything else seems to be the same...temps at the vent are still 58 - 60...

any thoughts or ideas that haven't been mentioned?
thanks, david

 

If your not getting these pressures for ford thermostatic switch 15-25 for low side High 180 - 225 something is still wrong. Make sure you have a big fan forcing air through the radiator and the engine at 1200-1500rpm. You pressures may/will be higher at idle.

Have you changed the thermostatic switch?

Did you use a hair drier on the sensing bulb to see if it was working correctly? I have seen some bad straight out of the box. Particurlary if they had been on the shelf a long time. The last time I bought a TXV it was charged with 134A and not R12.

 

I don't have a tach...so I dont' know what the RPM range is...I let it idle a little and then give it enough gas to make it pick up and run smoothly above idle. the pressures I gave you were at idle though. we have not changed the thermo switch. Didn't do the hair dryer test...was going to do that tonight...but our plans to run a few more test got put on hold til tomorrow night.

 

Cold moring starts the engine OEM setting was about 1600-1800 rpm with auto choke.
So maybe that will give you some idea of how much rpm to set it at when testing or charging you mr system.. my 2cents
orich..