A - C WALK ME THROUGH THIS ONE MORE TIME

[MIDNIGHT RIDER]

Okay, my A/C hose guy has ordered the (hopefully) correct fittings and has the measurements he needs to make a replacement dis-charge hose.

He has whatever I need to replace the low-side R134a valve/inlet/place-you-hook-the-gauge thingie.

I intend to go ahead and get the 38904 variable-orifice-valve so it will feel like hog-killing weather in July.

So..........., let's pretend I have screwed on all of my new goodies.

Now......, I connect to the vacuum-pump and pull a vacuum for how long ??

Will I have sucked out all of my compressor-oil ??

If I need to add oil, what do I need buy and how much do I need ??

Does the oil gravity-feed in, or is it sucked in by the reversal of the vacuum ??

I only know enough about this to get myself in over my head.


Thanks.

 

[RLDSL]

If you have not flushed the system, or drained off any componants, you have not lost any oil. Vacumming does not remove oil. it removes water. Vacuuming lowers atmospheric pressure in the system which reduces the boiling point of water to ambient temp so water boils at standing temp without heating it, then the vacuum removes it.
If you have been switching parts etc, pm me your email addy and I'll send you a Lubricant chart for calculating oil replacement. you just pour the oil into the system with a funnel, pour directly into the part replaced, if pouringinto a compressor, after connecting the hose, turn the compressor by hand at least 10 rotations to move the oil out of the thingand on into the condenser ( or better, just pour it into the condenser , oil is circulated through the system by the refrigerant, it pickes it up and carries it around so much at a t a time but not too much to lock the compressor )

You want to run a vacuum for at least 45 minutes depending on how strong your vacuum pump is and how long the system has been open and if you had to flush it out, if it's real nasty, may need to leave it on overnight.

 

[f350flatbed]

Pull vacuum for at least a few hours. It is best to flush the lines out with an AC flush kit first. The oil won't come out unless you drain it from the compressor and flush the lines. Then hook everything up and pull vacuum. Then put in the new oil and refrigerant. Some cans of refrigerant have the oil in them so you just hook it on and turn on the ac and fill er up. To get the oil out of the can you got to turn it upside down.

Paul B

 

[f350flatbed]

Wow, almost a simultanous post!

 

[MIDNIGHT RIDER]

R134a CAN TAP ???

There is a brass fitting that came with my new R134a gauge/hose set, brand-new in the box with no instructions whatsoever---I guess it wasn't meant for dumbies like me.


This fitting screws perfectly onto the threads of a refrigerant-can and the yellow-hose screws perfectly onto the other end of the fitting.

Within the fitting is a plain old tire valve-core.


I am assuming that the way this works is that by screwing the yellow-hose onto the fitting, it in turn forces the "pin" of the valve-core to pierce the refrigerant-can; and, by leaving the fitting attached to the can, the yellow-hose can be removed and the valve-core will seal the remaining contents in the can.


Do I have the right idea about all of this or am I way off base ??


In other words, is this brass fitting supposed to be the "can tap", or do I need something different ??



Thanks.

 

[RLDSL]

There is a brass fitting that came with my new R134a gauge/hose set, brand-new in the box with no instructions whatsoever---I guess it wasn't meant for dumbies like me.


This fitting screws perfectly onto the threads of a refrigerant-can and the yellow-hose screws perfectly onto the other end of the fitting.

Within the fitting is a plain old tire valve-core.


I am assuming that the way this works is that by screwing the yellow-hose onto the fitting, it in turn forces the "pin" of the valve-core to pierce the refrigerant-can; and, by leaving the fitting attached to the can, the yellow-hose can be removed and the valve-core will seal the remaining contents in the can.


Do I have the right idea about all of this or am I way off base ??


In other words, is this brass fitting supposed to be the "can tap", or do I need something different ??



Thanks.

Usually the way those work is you back the valve all the way out , counterclockwise ( so you don't wind up with a faceful ) then like you figures, thread it on the can, then crank the valve down clockwise and it will puncture the can.as you open the valve it lets the refrigerant into the hose, go ahed and hook it to the low side fitting and you're good to go. No need to have anything running at first for that first can. Right after vacuuming the system, it will suck most of it in right off the bat. Wait till you hear it equilize, then fire it up and chances arre there will be anough pressure in the system to where you won't need to run a jumper wire across the presure switch terminals to get the clutch to engage, but if not, pull the connector off the presure switch on the accumulator and run a jump wire across the terminals to fire the clutch up. Once the system is near full charge, make sure to remove the jump wire and plug the thing back in so you don't ice the system

 

[MIDNIGHT RIDER]

BIG THANKS TO ALL YOU GUYS

I got the new hose installed, the replacement variable orifice valve in, and replaced the low-side valve-housing.

I pulled a strong vacuum, let it hold a good while, then charged it with four 12-oz cans of R134a --- three were the lubricant-added stuff and one plain.


In mid-90 heat, direct evening sun, sitting still with engine idling, and both doors open, it registered 50* on one of those pencil-type probe thermometers stuck in the vent.


With both doors shut, revving engine to a steady 2000-rpm, truck still sitting still, it pulled down to 46* at the vent.


I may still add a fifth can, as it was still well within the BLUE portion of the gauge.


I am anxious to see how it performs at highway speeds.


Thanks for everyone's help and guidance.

 

[MIDNIGHT RIDER]

MORE A/C THREADS OF INTEREST

Valve core info :

http://www.oilburners.net/forums/showthread.php?t=24434


Dis-charge hose :

http://www.oilburners.net/forums/showthread.php?t=23996


Variable orifice valve :

http://www.oilburners.net/forums/showthread.php?t=24317


Please post your links to any other A/C threads within this thread for the next interested soul.


Thanks.