@TXSunDevil & @flintknapper : Thank you-
A/C servicing; vacuum, oil and charge system? (5 Viewers)
- Thread starter 2001LC
- Start date
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I try your idea @abuck, using my infrared temp gun. Shot a 41 F inside the vent with OAT of 92 F. I'm happy and COOL!
That is EXCELLENT. In most cases...if you can achieve vent temps 30° F below ambient...you've done pretty good. 35-40° F. is getting ALL that can be had. Good job!
- Thread starter
- #84
Thanks again to all especially you @flintknapper and @white_lx , for all your help on my last project The Unicorn my first AC job.
Seems good place to post this although I'll be hunting a leak and on different rig.
I'm working on a 00LX w/558km. AC blowing warm. Lexus history show system charged by Lexus Dealer with 2.42lbs at 467km on 8/5/14, then again ?.?lbs at 488km on 5/6/15. Rig parked (no start condition) for about 6 months or longer, until I recently got running.
I'm thinking I'll vacuum AC system, add dye, charge with 3 cans. Should I add oil, if so how much do you think will be safe amount and where should I add (at what point is best)?
Note: You once made mention mechanics will often add oil when charging to be safe. I don't want to have run dry or over oiled. So this seem a bit of a crapshoot to get a good balance of oil!
Seems good place to post this although I'll be hunting a leak and on different rig.
I'm working on a 00LX w/558km. AC blowing warm. Lexus history show system charged by Lexus Dealer with 2.42lbs at 467km on 8/5/14, then again ?.?lbs at 488km on 5/6/15. Rig parked (no start condition) for about 6 months or longer, until I recently got running.
I'm thinking I'll vacuum AC system, add dye, charge with 3 cans. Should I add oil, if so how much do you think will be safe amount and where should I add (at what point is best)?
Note: You once made mention mechanics will often add oil when charging to be safe. I don't want to have run dry or over oiled. So this seem a bit of a crapshoot to get a good balance of oil!
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Also consider putting in a new dryer cartridge before pulling a vacuum as the reply above says.
The total system oil capacity with front and rear AC is 6 ounces. Double end closed PAG-46 oil (Denso ND-8 equivalent) is preferable, but single end closed variants, which are cheaper, work well for a while too, but degrade quicker with moisture ingress over time.
I can find no published (Toyota) data for the amount of oil required....but everything I've ever read from other sources suggests 7.4 to 8.0 ounces for a Single Evap (front only A/C) unit. So...I would think a solid 8.0 to 9.0 ozs. would be appropriate for a dual unit...in order to keep the ratio correct.
But...I am happy to concede if anyone can show me hard data otherwise.
With re-charges, I'm always a bit concerned that oil leaked out and was not replaced. Owners may also have topped up the system themselves. Before you know it there is no oil left and the compressor seizes or gets damaged. Since this system may have a leak and been open to atmosphere, there could also be internal corrosion from the hygroscopic oil.
I'd start with checking the compressor. Can you turn it by hand (clockwise)? If that is the case, then that is a good start! You can remove the discharge line from the compressor and check for aluminum shavings if you are not sure about compressor issues. Use a q-tip in the compressor outlet after you remove the line.
If there is a leak on on these vehicles (especially from Canada), I would immediately suspect the pressure and suction line right at the little guard behind the passenger wheel well. The guard and the clamps hold dirt/salt and the lines often corrode there. You could pressurize the system with air and check for leaks in that are.
I'd just add ~ 4 oz of oil. I'd take reduced cooling over a seized compressor. Especially with all the carnage that results from that (new compressor, new condenser, new expansion valve, new discharge line - if there is a muffler).
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I know from a Robinair source that the maximum oil to charge in the UZJ100 is 6 ounces, if all charge has been lost. If topping up, 1 oz of oil per pound of refrigerant added is suggested. You may be correct for the total capacity, but I think that all of the oil is very hard to remove, hence 6 oz for replacement sounds about right.
Over the years, Toyota has reduced the capacities. The 200 series is down to about 4 oz, I think.
- Thread starter
- #91
So seem I lost 3 PSI overnight or would the 25 F drop in OAT account for drop in IN Hg?
So here's what I've done so far on this 2000 w/350K miles:
Verified compressor turns freely, smoothly and with light resistance by hand, turning clutch from just in front of pulley/belt.
With engine running at 1,500 RPM A/C on full front & Rear windows open. OAT 89 F at ~5,200' elevation. I check the following:
188 F. Temp of return (L) tube at compressor.
169 F. Temp of discharge (H) tube at compressor.
Movement of Fluid seen in sign glass, no bubbles observed. (Time to go from cabin turning A/C off to front about 2 seconds. So not watching sight glass during shutdown).
Readings at manifold:
L 7 PSI, H 133 PSI at 800 RPM
L 0 PSI, H 133 PSI at 2,000 RPM (FSM L 0.15-0.25 MPa / L 21.7 - 36.25 PSI, H 1.37-1.57 MPa / H 198-227 PSI)
L 45 PSI, H 45 PSI at 0 RPM (engine off)
Bled off a little gas at manifold, just to see what I'd get. Just barley opening value for ~1 seconds, I saw just a little fluid splatters in sight glass of manifold. PSI drop to 22. Open valve again and escaping gas stopped in just ~2 seconds (no solid/liquid discharged into catch cup) PSI dropped to 0 at manifold.
Pulled 26 IN Hg vacuum for 10 minutes.
26 IN Hg after 1 hour (OAT 88 f.)
23 IN Hg after 12 hours (OAT 63 F.)
So seem I lost 3 IN Hg overnight or would the 25 F drop in OAT account for drop in PSI?
So here's what I've done so far on this 2000 w/350K miles:
Verified compressor turns freely, smoothly and with light resistance by hand, turning clutch from just in front of pulley/belt.
With engine running at 1,500 RPM A/C on full front & Rear windows open. OAT 89 F at ~5,200' elevation. I check the following:
188 F. Temp of return (L) tube at compressor.
169 F. Temp of discharge (H) tube at compressor.
Movement of Fluid seen in sign glass, no bubbles observed. (Time to go from cabin turning A/C off to front about 2 seconds. So not watching sight glass during shutdown).
Readings at manifold:
L 7 PSI, H 133 PSI at 800 RPM
L 0 PSI, H 133 PSI at 2,000 RPM (FSM L 0.15-0.25 MPa / L 21.7 - 36.25 PSI, H 1.37-1.57 MPa / H 198-227 PSI)
L 45 PSI, H 45 PSI at 0 RPM (engine off)
Bled off a little gas at manifold, just to see what I'd get. Just barley opening value for ~1 seconds, I saw just a little fluid splatters in sight glass of manifold. PSI drop to 22. Open valve again and escaping gas stopped in just ~2 seconds (no solid/liquid discharged into catch cup) PSI dropped to 0 at manifold.
Pulled 26 IN Hg vacuum for 10 minutes.
26 IN Hg after 1 hour (OAT 88 f.)
23 IN Hg after 12 hours (OAT 63 F.)
So seem I lost 3 IN Hg overnight or would the 25 F drop in OAT account for drop in PSI?
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Why did you change the oil in the vacuum pump every hour? Is that a requirement? I have a 21 gal. compressor and assume its the same oil used. I change the compressor oil once a year. If you left the vac on all night how did you sleep? 
Why did you change the oil in the vacuum pump every hour? Is that a requirement? I have a 21 gal. compressor and assume its the same oil used. I change the compressor oil once a year. If you left the vac on all night how did you sleep?
Vacuum pump oil is different than compressor oil.
Ah.... I see now. Vacuum pump oil is different in that it absorbs moisture. Changing it regularly improves moisture removal and allows for a better draw. I don’t think I’ll need to change it every hour though. Seems overkill for an auto AC.
Thanks!
Thanks!
- Thread starter
- #95
I'm going to pull vacuum for 10 more minutes at 26 IN Hg. Then close valves on line ends (at vehicle) and disconnect. I'll leave caps off H & L hookup points of A/C system (exposing schrader valves). Then I'll drive around today, not using A/C. I'll also pull vacuum on hoses of manifold, then close off at manifold also.
I'll check to see if any loss of vacuum in manifold/hoses. Then I check to see if loss in A/C system.
Notes:
I had yellow line attached at both end to manifold overnight. When I disconnected one end of yellow (from static hanger fitting) i heard a puff of air. PSI drop 1 psi in manifold to 22 psi at this time.
As far as oil in vacuum pump, I've not changed it. Pump history is in this thread. Basically it's new being used only one time before in June. I suppose it would be best for life of pump, to drain after this job for storage and replace oil next job I use it.
I'll check to see if any loss of vacuum in manifold/hoses. Then I check to see if loss in A/C system.
Notes:
I had yellow line attached at both end to manifold overnight. When I disconnected one end of yellow (from static hanger fitting) i heard a puff of air. PSI drop 1 psi in manifold to 22 psi at this time.
As far as oil in vacuum pump, I've not changed it. Pump history is in this thread. Basically it's new being used only one time before in June. I suppose it would be best for life of pump, to drain after this job for storage and replace oil next job I use it.
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Gentlemen, let's not over analyze this or go to extremes.
Hook your vacuum pump back up with NEW pump oil. You can use pump oil consecutively (in a short period of time) for a couple of jobs, but you can't store it in the pump and then use it later (if that is what you did). When you store your vacuum pump...drain the old oil out of it first.
Pull a vacuum for an hour or so. Shut off the high and low side valves while the pump is still running. Note the reading (adjusted for your altitude) and IF it is acceptable then let the system rest for an hour. Come back and check the vacuum (in. Hg) IF it hasn't leaked down within an hour...you should be fine.
Leaving the system to rest overnight (a system with older components) is going to result in some loss of vacuum. The front compressor seal is old and not 100%. It has taken a 'set' against system pressure and static pressure and will probably hold both reasonably well...but now you are pulling it another direction. Also...there is always some residual refrigerant and oil in an old system that will tend to want to boil off. So a slight loss of vacuum is nothing to be alarmed about.
If you are using a single stage pump instead of a two stage pump....don't expect to get as deep a vacuum. Also, unless you have access to a micron gauge, we are guessing at the completeness of the evacuation anyway. That is why I recommend vacuuming for at least 2 hrs. on an old system.
Bottom line: You are fine...if the system holds vacuum for an hour after shut down.
Now....IF you had all NEW components, all new O-rings and had Nylog'd everything...then yes I would expect better from it. But for what you have, vacuum it, charge it....move on.
Hook your vacuum pump back up with NEW pump oil. You can use pump oil consecutively (in a short period of time) for a couple of jobs, but you can't store it in the pump and then use it later (if that is what you did). When you store your vacuum pump...drain the old oil out of it first.
Pull a vacuum for an hour or so. Shut off the high and low side valves while the pump is still running. Note the reading (adjusted for your altitude) and IF it is acceptable then let the system rest for an hour. Come back and check the vacuum (in. Hg) IF it hasn't leaked down within an hour...you should be fine.
Leaving the system to rest overnight (a system with older components) is going to result in some loss of vacuum. The front compressor seal is old and not 100%. It has taken a 'set' against system pressure and static pressure and will probably hold both reasonably well...but now you are pulling it another direction. Also...there is always some residual refrigerant and oil in an old system that will tend to want to boil off. So a slight loss of vacuum is nothing to be alarmed about.
If you are using a single stage pump instead of a two stage pump....don't expect to get as deep a vacuum. Also, unless you have access to a micron gauge, we are guessing at the completeness of the evacuation anyway. That is why I recommend vacuuming for at least 2 hrs. on an old system.
Bottom line: You are fine...if the system holds vacuum for an hour after shut down.
Now....IF you had all NEW components, all new O-rings and had Nylog'd everything...then yes I would expect better from it. But for what you have, vacuum it, charge it....move on.
- Thread starter
- #99
I've a question:
Are the A/C schrader stem valves just the same as tire stem valve?
I asked because that is all I have/found to replace the A/C L & H ports stems with.
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Here what I did last ~72 hours:
I had manifold hang in shop all valves closed after pulling 26 IN Hg. While I drove the 00LX around town, which also had vac pulled to 26 IN hg. OAT has been between 54 - 95 F in the mile high city.
I picked up a qt of Black Gold for $10 at HVAC supply house and changed my pump oil. I also picked up two valve stems (auto tire), A Denso dryer ( 478-1500 A/C receiver) and three 12 oz cans of R-134a.
Vacuum in manifold/hoses started at 26 InHg and ended after 48 hrs at 21 IN Hg. So looks like I was leaking a bit at/from manifold itself.
Hook up vacuum pump and pull 26IN Hg on manifold & hose, with L & H hose end valves closed. I then attached hose ends to my H & L ports of AC system, and with pump running I close manifold side of valves the turn off the pump. Now with vacuum of 26 IN hg in manifold and hoses I opened the H & L valves at hose ends. My "L" gauge dropped to 20 IN hg. So these tests indicates a leak in both my manifold and in the OOLX A/C system.
I then turned the pump back on and open all valves. I sungged down (open) valve at the manifold, as this was likely the a leak point. Pulled Vacuum which took about 2 minutes to reach 25.8 IN Hg from 20 IN hg it was at. System reached to the high side of 26 IN hg in about 5 mins. After about 2 1/2 hours of pulling vacuum, I closed manifold valves a turned off the pump, with L gauge reading 26 IN hg.
1 hour later reading was 26 IN hg
2 hours later reading was 26 IN hg.
Next morning (~14 hrs) system was still read 26 IN hg.
It also keep 26 In Hg in manifold and 10 hours later it was also holding 26 In hg. Snuging down the manifold valves seems to have stop that leak.
I'm thinking:
If leak in metal such as piping, condenser, ect. it would leak under pressure or vacuum always.
If leak in a seal (O-ring) may leak under pressure then possible not in a vacuum.
If leak is in schrader valve, it would not be a detectable leak with manifold connected.
I reconnected manifold again after 10 hours to see if vacuum dropped in A/C system while driving around today with a OAT of 77 to 90 F. Nope this time it held 26 In hg.
What do you think; just fill it with 3 cans w/R134a, new dryer and valve stems see what it does?
Perhaps I should hold back on installing the new dryer?
Are the A/C schrader stem valves just the same as tire stem valve?
I asked because that is all I have/found to replace the A/C L & H ports stems with.
___________________________________________________________________
Here what I did last ~72 hours:
I had manifold hang in shop all valves closed after pulling 26 IN Hg. While I drove the 00LX around town, which also had vac pulled to 26 IN hg. OAT has been between 54 - 95 F in the mile high city.
I picked up a qt of Black Gold for $10 at HVAC supply house and changed my pump oil. I also picked up two valve stems (auto tire), A Denso dryer ( 478-1500 A/C receiver) and three 12 oz cans of R-134a.
Vacuum in manifold/hoses started at 26 InHg and ended after 48 hrs at 21 IN Hg. So looks like I was leaking a bit at/from manifold itself.
Hook up vacuum pump and pull 26IN Hg on manifold & hose, with L & H hose end valves closed. I then attached hose ends to my H & L ports of AC system, and with pump running I close manifold side of valves the turn off the pump. Now with vacuum of 26 IN hg in manifold and hoses I opened the H & L valves at hose ends. My "L" gauge dropped to 20 IN hg. So these tests indicates a leak in both my manifold and in the OOLX A/C system.
I then turned the pump back on and open all valves. I sungged down (open) valve at the manifold, as this was likely the a leak point. Pulled Vacuum which took about 2 minutes to reach 25.8 IN Hg from 20 IN hg it was at. System reached to the high side of 26 IN hg in about 5 mins. After about 2 1/2 hours of pulling vacuum, I closed manifold valves a turned off the pump, with L gauge reading 26 IN hg.
1 hour later reading was 26 IN hg
2 hours later reading was 26 IN hg.
Next morning (~14 hrs) system was still read 26 IN hg.
It also keep 26 In Hg in manifold and 10 hours later it was also holding 26 In hg. Snuging down the manifold valves seems to have stop that leak.
I'm thinking:
If leak in metal such as piping, condenser, ect. it would leak under pressure or vacuum always.
If leak in a seal (O-ring) may leak under pressure then possible not in a vacuum.
If leak is in schrader valve, it would not be a detectable leak with manifold connected.
I reconnected manifold again after 10 hours to see if vacuum dropped in A/C system while driving around today with a OAT of 77 to 90 F. Nope this time it held 26 In hg.
What do you think; just fill it with 3 cans w/R134a, new dryer and valve stems see what it does?
Perhaps I should hold back on installing the new dryer?
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