- Thread starter
- #21
Also, how long has taken for you to empty a normal sized can in the high side?
Recharging AC Help! (1 Viewer)
- Thread starter 4lo co
- Start date
-
- Tags
- ac ac compressor
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
Not that long, a few minutes tops. The vacuum will pull most of it in almost immediately, then I let it sit for a couple minutes to fully empty.
I went through this twice last weekend after I forgot to tighten a fitting on a line and will do it again this weekend as I gambled on the original evaporator that I forgot to order a replacement for. Yep, it leaks...
It took a loooong time for the system to take in 2 cans of Freon for me. I didn’t try the high side method, will probably do that this time to start.
Took close to two hours to get two 12 ounce cans in. Didn’t top it off as I had a feeling the evaporator was toast. Putting the cans in a cup of hot water really helped speed things up, but it still took time. I’ve read the rental manifold gauges can be crap too causing issues.
It took a loooong time for the system to take in 2 cans of Freon for me. I didn’t try the high side method, will probably do that this time to start.
Took close to two hours to get two 12 ounce cans in. Didn’t top it off as I had a feeling the evaporator was toast. Putting the cans in a cup of hot water really helped speed things up, but it still took time. I’ve read the rental manifold gauges can be crap too causing issues.
You did use a vacuum pump to Evacuate the system?
- Thread starter
- #26
I did
- Thread starter
- #27
Brian,
Did as you instructed and the system took the whole can on the high side in a few minutes. Turned the land cruiser on and started trying to fill the low side. Pressure was around 130 and wasn't taking freon. Clutch was engaged as soon as I turned the A/C on. I then stopped trying to add more, closed the low side line and turned the A/C completely off. The clutch was still running when I turned off the A/C. I'm assuming that's not normal and a switch has gone bad that signals it to cut off?
So much to digest here.
Let's just start over.
Your previous compressor seized, I got that.
You replaced the Condenser (good move), the Compressor (good move), the drier (good move), the TXV (good move) but not the Evaporator?
You stated that you flushed the "system". Hopefully by that you meant the remaining lines? IF that is correct...please tell me the procedure you used.
When you replaced the TXV...did you find any metal particles or anything else in the screen?
When you installed the Condenser and Drier did you add some oil directly into those components (about 1.5 ozs each) and then the remainder in the compressor to achieve about 7.5-8.0 ounces of PAG46 total?
I have more questions to follow these, but let's do this methodically and address the above first.
Let's just start over.
Your previous compressor seized, I got that.
You replaced the Condenser (good move), the Compressor (good move), the drier (good move), the TXV (good move) but not the Evaporator?
You stated that you flushed the "system". Hopefully by that you meant the remaining lines? IF that is correct...please tell me the procedure you used.
When you replaced the TXV...did you find any metal particles or anything else in the screen?
When you installed the Condenser and Drier did you add some oil directly into those components (about 1.5 ozs each) and then the remainder in the compressor to achieve about 7.5-8.0 ounces of PAG46 total?
I have more questions to follow these, but let's do this methodically and address the above first.
- Thread starter
- #29
Correct, the evaporator was not replaced. Also, correct in that I flushed the remaining lines and evaporator. I did so by using one of the pressurized ac flush kits with Johnsen's Flush solvent and just blowing the solvent through the lines/evaporator.
I added a total of a little over 7 ounces of PAG46. I did NOT add to condenser and drier, but straight to the compressor so it sounds like I may have messed up there. Not sure how big a deal it is.
Currently, where I'm at, the system holds a vacuum, it'll take in r134 through the high side with vehicle off, but doesn't seem to be taking any in through the low side. If it is, its going very slowly. With the gauges hooked up and vehicle running, low side pressure is over 100 and high side pressure is around 150 with one can of r134.
To be clear.... you are pulling a vacuum on the system, then charging the first 12 ozs (1 small can) into the vacuum through the high side as a liquid (engine and A/C off)?
And that procedure would be as follows:
Manifold gauge set would be hooked up to the vacuum pump (refrigerant or Aux hose), Low side hose (blue) hooked to low side port, High side hose (red) hooked to high side port. ALL valves open. Vacuum pump (with fresh, good quality pump oil) runs for at least an hour. You pull 28-29 in. Hg (depending upon altitude). You shut off ALL valves at the manifold while the pump is still running. Watch low side gauge to insure you are not losing vacuum. 30 minutes should be plenty. If no significant leak down...then you are ready to liquid charge.
1. Disconnect the REF line (yellow) from the pump (all valves are still closed).
2. Use your can tap to hook up a can of R134a to the REF hose.
3. PURGE the hose! IF the manifold has a schrader valve..depress it for a couple of seconds until you get slight 'hiss' of refrigerant. IF it doesn't have a schrader valve then SLOWLY back off the knurled fitting at the manifold just until you get a slight refrigerant discharge then tighten back up (don't over-tighten).
4. Invert the can so the can tap is at the bottom, this will force only liquid R134a to be drawn into the system.
5. Now its 'show time'. Open the high side valve ONLY...all the way. A properly vacuumed system should easily take in the first can (12 ozs.). It won't take very long, perhaps a couple of minutes. You will feel the can get lighter and colder.
6. Once you suspect all or most of the contents of the can have been emptied...close the high side valve. YOU WILL NOT OPEN THE HIGH SIDE VALVE AGAIN, we are done with it. But leave it hooked up...because obviously we need to monitor high side pressure.
Why do we first charge an evacuated system into vacuum through the high side?
1. It's the fastest, easiest way to get a partial (but sufficient) charge into the system.
2. It insures there will be enough system pressure to activate the low pressure switch right from the start.
3. You will have enough liquid refrigerant (right from the start) to carry the lubricating oil through the system.
4. You don't have to dick around with jumping wires, switches, clutches, etc...while you wait to get enough refrigerant in through the low side as a vapor. Leave that to the novices.
At this point you should have ALL valves shut off. Go ahead and connect another can of refrigerant to the yellow REF line and purge the line as before. From this point forward...we will be charging the remainder of the refrigerant though the LOW SIDE as a VAPOR. This might take awhile so be patient.
You'll want to start your engine. Put the A/C on max, blower on high, system on recirculate, windows open. This can be done at idle or at elevated idle (up to 1200-1500) doesn't matter that much at this point. So..with the new can hooked up...line purged we are ready to crack open the low side valve. Make sure the can of freon is upright (can tap at top of can). Do NOT open the low side all the way. This is the most common mistake folks make. The system will take in a LOT of vapor quickly and the pressure will spike (80-120 psi) on the low side gauge. This is what freaks folks out. Just open the valve gradually so that pressure stays around 50-75 psi. You can open it more or less to maintain it. Don't just open it and walk away.
As the system takes in more refrigerant it will naturally begin to slow down (take longer to empty a can), this is normal. It's OK to just slightly tilt the can occasionally while watching the gauge, you will see a spike in pressure. Also see liquid freon if the gauge has a sight glass. Only do this in small amounts for a second or two.
After you have introduced about 2/3rds to 3/4 of the recommended 'weighted' amount, we will need to start checking our pressure. BOTH high and low side. The Valves on the manifold set need to be turned off to take the pressure reading. The high side is already off (remember after liquid charging it never gets opened again), so just turn off the low side valve.
Let the system run for about 5 minutes to stabilize. Then note your pressure readings. Look to see that the gauge needles are not fluttering. IF the compressor cycles...that is fine, just note the maximum pressure on both gauges. Record the ambient (outside temperature). Let us know what those are. Let's not try to get any more freon charge than this...until we determine if you have other issues or not (inappropriate pressure readings, etc..).
Do you have some way to take temperature readings at the middle vent at the dash?
Last edited:
- Thread starter
- #32
Ok, I have done this to a tee EXCEPT I open the low side fully when I do it, thus getting those high pressure numbers (80-120) on the low side you mentioned. I will reattempt all steps again as you've described and get back with the readings.
Excellent. So...to recap, while we DO watch our gauges as we charge the system...you won't get true (stable) pressure readings until you have shut off the low side valve and let the A/C run for a few minutes to stabilize.
IF you still have high (low side) pressure and normal high side pressure (for the ambient temp) then let us know. There are only a couple of reasons for that (one involves your manifold gauge or hoses, the other your TXV).
Take your time, be methodical....you're getting there.
Good on ya, @flintknapper. Posts like your last two are why I read 'mud.
- Thread starter
- #35
Ok, so I did as you instructed. Filled high side with one entire can with vehicle off (liquid fill) and attempted to fill low side (with vehicle on), but compressor would not take the r134. I shook the can (not upside down) for about 50 minutes before I stopped because I felt I was making no progress at all (r134 can felt about just as full as when I started).
What were/are your high and low side pressures? What was the ambient temperature?
Also, I would like for you to perform a couple of mechanical tests. IF no (or little) refrigerant is going into the low side (engine on, compressor running) then are only a few reasons why that might be.
1. Compressor is faulty.
2. Obstruction in charging hose or gauge manifold set.
3. Incorrect valve position (low side valve not open).
4. Obstruction in A/C system.
Note: Wear safety glasses and gloves.
Let's begin with the Schrader valve at the service port on your compressor. Engine OFF, locate the low side service port on your A/C compressor. Quickly depress and release the schrader valve and note IF you get a forceful (and brief) discharge of refrigerant. We do this to establish that the S-Valve is capable of being fully depressed and the port is not obstructed in any way. IF you get a discharge...move on to the next step. IF you do not...then stop and let us know.
Step two: If the service port and S-Valve are working correctly then next thing we need to determine is IF when the low side is connected...that the coupler is fully depressing the S-Valve and that there is nothing obstructing the hose.
To do this: Engine OFF, take your manifold gauge set (all valves closed) and connect the low side hose ONLY to the low side service port. Take the end of the yellow (REF) hose and point it in a safe direction where any expelled refrigerant will not get on you or the vehicle. Quickly open then close the low side valve on the manifold and observe whether or not you get a discharge from the end of the yellow (REF) hose.
Just open the low side valve about 90° and then quickly close it. Just enough to let refrigerant escape.
IF you see a discharge then we can assume the manifold set and hose are clear and capable of allowing refrigerant to enter the compressor. IF not...then we need to find the problem with the gauge set.
Let us know what you find and we will move on from there.
- Thread starter
- #37
Low side pressure was around 105-110 and high side pressure was just under 150. The ambient temperature outside was 80F.
- Thread starter
- #38
So I think I found the issue. The r134 adapter to the service port is not pushing in the original r12 Schrader valve in deep enough. To test this, I took the top cover off the compressor which houses both the high side and low side service ports. I then attached the gauge hoses to the service ports with the r134 fittings. I then blew threw the hoses with compressed air. The air blew through the high side but not the low side. I then took off the r134 fittings. I have an old r12 set of gauges with fitting and put it on the service ports with the original r12 fittings. This time compressed air was blowing through the low side, albeit nowhere near as hard as the high side.
So...there ya go! That is the value of doing the mechanical test.
Another thing that will trip folks up is over-tightening the screw on fittings. It can result in a crushed seal that blocks the flow of the fitting/hose, so watch for that too.
- Thread starter
- #40
So that indeed was the issue. To solve my problem I had to use the r12 fitting to fill the freon from the low side. Found an old r12 gauge set I had lying around and bought some brass pipe fitting to adapt the r12 low side hose to the r134 gauge. I then proceeded to fill 2 12 ounce cans (first one in high side with vehicle off). I filled with the third can for just a minute or two (guessed since I didn't have a scale). Low side pressure read 35 psi and high side read just under 150 psi with the ambient temperature being 74F (and this was observed with the engine idling). Based on a few generic charts I found on google for R134 pressure in relation to ambient temperature that seemed to be within spec though I've read other threads here ideal is around 30-35 psi low side, 200-220 high side. Today at an ambient temp. of 85F or so, low side read 35 psi and high side read around 250 psi. I found the high side to be a little too high but i also was having issues with the high side hose (overtightened at first and wasn't getting a reading at all like you mentioned previously) so I'm going to retest tomorrow after messing with the hose and make sure its working properly. My vent temp at idle is right at 60F and when driving gets down as low as 47F at higher speeds (I'd say over 40 mph).
Really appreciate the help @flintknapper, your instructions were top notch and I think they're going to help a lot of people in the future. Guys like you make Ih8mud the great forum that it is!
