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Fred85
July 4th, 2006, 16:31
2001 sanden compressor....bought the jeep with 57k on the clock, got 68k on it now

not sure if the a/c has ever been serviced, carfax report of maintenance didn't list anything regarding the a/c system but that's not really saying much

anyway, i was going to add some r134 because the vent temps don't seem as cold as the fsm says they should be.......the problem, seeing that i dont know if the system has ever been serviced, is that i'm not sure if it needs oil or not......any help?

and please no one tell me to check for a leaky evap lol, i'm aware of the quality of these evaps

Rick Anderson
July 5th, 2006, 07:24
AC systems are hermetically sealed, they do NOT need any servicing for normal operation.

The most common problem is they do leak a small of amount of refrigerant over time, which sounds like your problem.

If the system had been repaired and/or serviced any oil lost should have been replaced during the servicing.

Having said that, if you suspect there has been a refrigerant leak, the oil does mix with the refrigerant and can leak out with it. Inspect the system, especially low points and see if you can spot any leaking oil. That is the spot to repair for your leak.

There is no way to measure how much oil is in the system, other than dissassembling the entire system and draining each part individually (and you'll probably never get all the oil out of the compressor). You really have to guess, and too much oil is better than not enough. Too much oil will displace refrigerant and the AC will have slightly less cooling capacity, too little oil the compressor will not have enough lubrications and will wear or sieze. Personally, if I have to add some refrigerant to the AC system, I add an oz or two of oil every other time I add refrigerant. You can find the R-134a cans with oil in them. Use the PAG oil, not the POE, since thats usually the OEM oil for R-134a, POE is a conversion oil that is not as good as PAG, but more tolerant of old R-12 and mineral oil that can be left behind during conversions. Most cans of R-134a/Oil will use POE oil, read the label carefully.

I would NOT add R-134a just willy nilly out of a can, you should have a set of gauges that tell you the actual pressures of the system while you service the system. Its easy to add too much refrigerant and the system pressures will go to high and either shut-down or vent the refrigerant.

If you want to do this on the cheap, and are willing to risk the AC system, then run the motor and AC system on max capacity, turned all the way up windows open, etc. Add the R-134a/oil (read the can carefully, sometimes cans with oil must be charged upside down) to the low side of the system while watching the return line from the evaporator at the firewall. When that return (low side) line at the firewall starts to form heavy condensation, your full of refrigerant, stop charging.

Saudade
July 5th, 2006, 08:49
As Rick says, the only way to be sure your problem is from a low refrigerant level is by using a gauge set. I don't know if you have one but my '88 XJ has a sight glass where I can see the freon charge. Before I got my gauges, I used to add freon until the bubble went away.

Since low discharge temps could be caused by other things (i.e. blend door problem, etc.) I'd try to make sure it as a refrigerant problem before tinkering with the system.

Rick Anderson
July 5th, 2006, 08:54
The sight window only worked with R-12 and an '88 XJ would probably have R-12. BUT, with R-134a, the refrigerant is going to bubble when its properly serviced, so the sight glass is useless with R-134a, thats why you don't see them on the newer R-134a systems.

Fred85
July 5th, 2006, 20:59
i'm aware of the guage set that you refer too, the fsm has a pic of one

i was going to buy the can with the el cheapo guage on top, good enough?? lol

what i was planning on doing is adding r134, checking pressure.............and coming back in a month or two and checking again to see if pressures have changed to see if i have a leak, then i'll go from there

Rick Anderson
July 5th, 2006, 21:09
The gauge on top of the can really tells almost nothing. You need to see the high side and low side pressure, when there is no refrigerant being introduced in the system.

Just the low side pressure is 1/3 the story, you need to know the High Side pressure and the difference between the two too really get a picture of what is going on.

The condensation on the suction line from the evaporator at the firewall will probably tell you more than just the low side pressure. With barely enough refrigerant, you'll be able to get the proper low side pressure, you probably need another 12 oz after that, but you can also overcharge the system by 20 oz and still keep the proper low side pressure.

When the suction line forms a heavy condensation, its moving enough heat, (a combination of pressure and volume) to be effective, meaning you've got enough refrigerant in the system to move the full capacity of heat that it is capable of doing. Stop as soon as the heavy condensation forms, because it will keep forming the heavy condensation way after you've overserviced it.

This is all assuming you live in an area that is half humid, you live in Arizona, I guess you can't use that technique.

lilredwagn
July 5th, 2006, 21:28
Interdynamics makes the HGT-134A which sells for $25-30 and can measure both low and high side pressures. Seen it available locally from Advance or O'reilly, or can be found online.

http://www.partsamerica.com/ProductDetail.aspx?mfrcode=IDN&mfrpartnumber=HGT134A

I haven't used mine yet - need to pick a day to hook everything back up and visit the shop to pull a vacuum first. Gotta call and find one that's willing to vacuum without filling and been to laz - er - busy.

Fred85
July 6th, 2006, 06:40
have i got to check both high and low side pressures at the same time??

the el cheapo guage is removable and the instructions say something along the line of check the line pressures first and then add refrigerant and check line pressures again, why can't i just do that?? just curious, i've never had any experience recharging ac systems

ive got an fsm, but it actually does't detail how to add refrigerant......just talks about the line pressures and the guage set

lilredwagn
July 6th, 2006, 10:23
IF your system is functioning 100% correctly and just needs more refrigerant, then you should be fine using the low-pressure only gauge. If there are any hidden problems in your system, though, it will just make things worse, whereas checking the low and high side would allow you to see if there were any problems.

You cannot check the high side pressure unless you have a gauge specifically designed for it. The idiot gauge that comes built into the can does not have the correct fitting, not to mention that it is designed to measure in the 50psi range. High side pressure can be more than 300psi. To my knowledge, with the exception of a manifold gauge, the product I linked to is the only one that performs this function.

Fred85
July 7th, 2006, 15:06
thanks for the info

lilredwagn
July 9th, 2006, 15:31
I just wanted to bump this up for anyone looking to do their own A/C, as I just found harbor freight has an entire manifold set for $32.

It's online price, so you will have to print it out and bring it to the local store if you are buying local (call first to verify stock).

It's a full 3 hose set with high and low gauges, and it does measure vacuum (which the gauge I linked to above does not). There's even a schrader valve on the center port, so you can purge the line without having to crack the connection.

It's typical made in China harbor freight fare, but it's a heck of a deal. I couldn't resist and went out and bought one myself even though I already had the gauge I listed above :o

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92649

fizassist
July 10th, 2006, 06:51
It's typical made in China harbor freight fare, but it's a heck of a deal. I couldn't resist and went out and bought one myself even though I already had the gauge I listed above :o

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92649

I've used this, and it works fine for low volume use. Heck of a price at $30.

kennzz05
July 10th, 2006, 20:58
not sure about 134 but r22 has a slight amount of oil mixed with it so as you charge you are essentually adding oil as well although it is a small amount

Blaine B.
December 3rd, 2006, 15:16
Is the system supposed to show FULL when the A/C compressor is running or not?

This summer I noticed the A/C was a little on the warm side.....well a little more than that. On a 90 degree day it was cooler to have the windows open than the A/C on max.....

I bought a can of 134 which had a gauge right on the included trigger nozzle.

When the system is off, it shows full, but when the compressor engauges it shows "yellow" (not entirely full)

I didn't want to overfill the system when the compressor was off, so I didn't add anymore........should I make the system full when running, even if it shows overfilled when off?

My uncle had a professional set of gauges, but when he tried to use them they didn't work right.....he was confused as well, they were over $100.00....heh.

lilredwagn
December 3rd, 2006, 19:40
Is the system supposed to show FULL when the A/C compressor is running or not?

This summer I noticed the A/C was a little on the warm side.....well a little more than that. On a 90 degree day it was cooler to have the windows open than the A/C on max.....

I bought a can of 134 which had a gauge right on the included trigger nozzle.

When the system is off, it shows full, but when the compressor engauges it shows "yellow" (not entirely full)

I didn't want to overfill the system when the compressor was off, so I didn't add anymore........should I make the system full when running, even if it shows overfilled when off?

My uncle had a professional set of gauges, but when he tried to use them they didn't work right.....he was confused as well, they were over $100.00....heh.

I would be concerned about the gauges not working right, and continue trying to rectify the operator error until they do work right or until the source of the problem is identified - as mentioned before, the can with gauge is only telling you half the story.

That said, the pressure that is being measured by the can gauge is intended to be read with the system operating. When the system is not operating, the pressure between the low and high side will equalize - raising the low side and lowering the high side.

Blaine B.
December 3rd, 2006, 22:04
The gauges were at fault. They were on both the high and the low correctly, but the gauges weren't functioning. Still have to figure that out before next year.

I don't see how the operator could be at blame. You hook up the gauges and go from there. That's all you can do.

lilredwagn
December 3rd, 2006, 23:05
The gauges were at fault. They were on both the high and the low correctly, but the gauges weren't functioning. Still have to figure that out before next year.

I don't see how the operator could be at blame. You hook up the gauges and go from there. That's all you can do.

In addition to snapping the quick-disconnect fittings onto the high and low ports, you also have to turn the wheels on those fittings to actuate the valves in the ports. Not that the gauges might not be faulty, but I'm guessing you might have missed this step because it took me two tries before I figured it out myself.

Blaine B.
December 3rd, 2006, 23:30
You mean the little quick-disconnect release wheels?

No! We didn't turn that.......

I don't recall being able to turn the wheel thing on my r134 canister though. Besides clamping it onto the quick disconnect, I had to keep pressure on the connection otherwise it wouldn't fill properly.......Like pushing down on the connection to give it a better seal.