A/C servicing; vacuum, oil and charge system? (4 Viewers)

[JAntosch]

Figured I'd post up here as well as this thread was immensely helpful in the proper way to recharge the system. Rear lines were leaking in the usual location behind the front passenger tire. Cut and capped lines in the engine bay, replaced desiccant, and pulled vacuum. Charged with 1 can R134a+oil on high side, and took a little over 1 can on the low side to get pressures in range (in line with the 0.8-0.9 kg estimate in another thread once the rear is removed from the system). Very happy to see 40* below ambient when stopped (no aux fan on the '04):

Used this pump and gauge set without issue:
Amazon product ASIN B077PY6NHR
Big thanks to @flintknapper and @2001LC for documenting the process!

 

[hickuptruck]

I just capped off the rear AC lines behind the front passenger wheel. The AC hasn't been run in at least a year - two, maybe more. When I first got the 2002 LX470, I thought I just needed a can of r134a. When I filled it up, AC started blowing cold, but it leaked all out within 5 minutes out of the leaking rear lines.

Do I need to add the PAG46 oil to the compressor?
How much r134a freon do I need to put in?

 

[gatormark91]

If you do not know how much PAG oil is in the system, you really cannot guess. You'd need to remove the compressor and blow out the lines with compressed air until no oil came out of the lines. After that, there will be about 1.2-1.4 oz in each of the evap and condenser. A fresh compressor will have ~8 ounces in it. Set the old compressor over a pan to drain for a couple hours, turning in by hand every now and then to pump more out.

So 8 oz - 3 oz = 5 ounces. Assume an ounce that you will never get out of the compressor. If you do this and add 4 ounces, I'd think it would be OK, with a little extra just to be safe. But the rear evap core is supposed to have a bit over an ounce of that 8 ounces, too, so not sure how to account for that not being in the loop??? Maybe just add 3, then?

But you can't really guess. If you put in too little, your compressor will not live long. If you put in too much, you won't get very good cooling.

As for how much Freon, after replacing the dessicant bag and vacuuming it out, add Freon until you get to a steady 30-35psi (going up to 40-42 when cycling while hot), and you should be good. With no rear AC, probably a bit over two cans would be my guess. I would go by pressure, and not the amount of Freon...

 

[2001LC]

I've got a problem with High pressure 250 to 275 PSI

I rechecked today with OAT of 93 F in shop. Air at intel for HVAC may have been a bit hotter from heat of engine.

Why is my "H" pressure so high, ranging 250 to 275 PSI?

Would volume of oil affect pressure, say if to much would it raise pressure?

Is there any danger of damaging system with these pressures?

Should I bleed some off from H side engine off, L side or just see if it hold these pressures?

FSM (if I did my MPa to PSI conversion correctly) is:
L 21.33 to 35.55 PSI
H 199 to 213.33 PSI

Low stabilized at max recommended ~35 to 35.5 PSI so good pressure there. But high is ranging 37 to 62 PSI over max.
Considering spillage, I put in less than 36 oz R134a in system. Minimum is 35.2, so I'd be right about minium. This assumes each can had the stated 12 oz.

Hooked up manifold with A/C on full, windows open, RPM 2K. At first engine was not quite yet to operating temp, A/C just turned on I get reads of L 37.5, H 275 PSI
View attachment 1791830
Over next few minutes "L" pressure stabilized at 35 to 35.5 PSI. High dropped also, but only to 250 PSI then climb some to 275 PSI moving around a bit.

After about 5 minutes seem to stabilize around L 35, H 260
View attachment 1791835 View attachment 1791851 View attachment 1791853 View attachment 1791854

So around last Sept 17, 2018 I posted work on Emerald's A/C. History from Lexus showed the system was being re-charge each of last two years PO had the LX. I vacuumed the system and it held vacuum. So seemed it did not have a leak. I subsequently charged with three 12OZ cans. All good so it seemed, but didn't use much as fall then winter cooler temps set in. Come the next spring & summer first time using A/C, it was a no go..

I've been very busy working on the locals rigs and getting Merlot ready for new owner (Brian) to take to HIH. Now I've finally one day in which to pull Emerald into the shop and check the A/C static pressure, before for more locals bring their rigs in for servicing..

Once in the shop I hook up an A/C manifold gauge set with engine and A/C off. It wasn't empty, but static pressure was down to 30PSI. Having just tested another local mud member's A/C static pressure, I knew 80PSI was what normal full charged looked like.

So back to square one, as it must have a leak right?.

So i started hunting for leak by pressurized system with 80PSI, using my home made tool hooked form my shop air hook to A/C manifold gauge set. This tool, which was recommend to me here in early in this thread, works great.

It held pressure. HUH!

After nearly and hour, no pressure loss.

So I pulled manifold valves for "H" & "L" off A/C system with 80PSI remaining in it. Then sprayed the schrader valves with soapy water to see if a leak may be there. No Bubbles so no leak indicated. HUH!

Next I pulled a vacuum and was getting ~25.5IN at ~80F in the mile high city. I let sit over night with manifold gauge set valves closed, in case any leaking valve on manifold. This way I'd not get false reading of a A/C system leak.

In the morning I checked to see if vacuum held, it did.
The vacuum drop by less than ~2IN from ~25.5IN to ~24IN. OAT Temp also drop by 5F degrees from 81F to 75.5F.


So why no sign of leak, either when pressurized or under vacuum?
Why was pressure down to 30PSI static, which indicates a leak?
Since it must have a leak, why not totally emptied (0 pressure)?

Could there be a place in system that perhaps as a valve or something opens, a leak is there only when system operating and not when off?
If so what/where would that be?

 

[flintknapper]

You can have a leak in the compressor's seal (front) and lose a charge that only occurs at certain a pressure threshold and as the unit warms up. They won't show up sometimes under vacuum because you are pulling the seal slightly inward. The normal influence (with system running) tends to be more outward pressure on the seal. I would look behind the clutch for evidence of a leak there.

If nothing found...then I am as stumped as you are about it.

And one note about static pressure: We can't use it to determine how much refrigerant is in the system, since the pressure will be the same for any amount of liquid refrigerant (1 oz. or 2 lbs.). But it is useful to determine if there is enough pressure to satisfy the trinary switch (to allow clutch engagement) and also for leak testing (minimum of 50 lbs.).

 

[2001LC]

You can have a leak in the compressor's seal (front) and lose a charge that only occurs at certain a pressure threshold and as the unit warms up. They won't show up sometimes under vacuum because you are pulling the seal slightly inward. The normal influence (with system running) tends to be more outward pressure on the seal. I would look behind the clutch for evidence of a leak there.

If nothing found...then I am as stumped as you are about it.

And one note about static pressure: We can't use it to determine how much refrigerant is in the system, since the pressure will be the same for any amount of liquid refrigerant (1 oz. or 2 lbs.). But it is useful to determine if there is enough pressure to satisfy the trinary switch (to allow clutch engagement) and also for leak testing (minimum of 50 lbs.).

So perhaps I should re-fill (charge) and add some dye as I do. Sound like a good plan?

 

[flintknapper]

So perhaps I should re-fill (charge) and add some dye as I do. Sound like a good plan?

You could continue looking for leaks with shop air and soapy water...but increase pressure. It won't hurt the system to put 120-150 psi on it. 80 psi might not be enough to get past a compressor seal (or manifold seal). I would concentrate on the compressor and any lines that have a foam cover on them. Insulation over a line will sometimes hide a leak and will also not show up with vacuum because a pin hole there sucks the insulation against the line. Use a 50/50 mix of soap and water and a spray bottle.

If you don't discover anything that way...then yes, dye might do the trick.

 

[2001LC]

So after exhausting my hunt for leak, with both positive pressure and vacuum not yield any pressure change or soap bubbles.

I added the dye. I'm still not sure, if I found a leak. Looking at compressor body with special yellow glasses and light that came with green dye kit. I'm just not sure if that seal is the leak. I see what may be microscopic green dots on compressor body aft of belt pulley. But really I'm not sure if just spec in metal that have variation in color. I'll run AC over time and just keep looking for the dye. I'll also get some other eyes on it.

But for now I charged it with 3 cans and has worked great for last month. For $7 a can, I can just add a can each spring if needed. Over time the leak may reveal itself. But if a very minor compressor seal, it may not be worth doing anything other than a quick charge/top off annually.

 

[white_lx]

I added the dye.

Does anyone know if Toyota ever added the dye in the factory? I was looking at another LX. The seller said the A/C had never been touched, but the sight glass showed the green dye. Make me a bit suspicious about the seller.

 

[2001LC]

I've never seen any sign of dye, that made me think factory added.

 

[flintknapper]

So after exhausting my hunt for leak, with both positive pressure and vacuum not yield any pressure change or soap bubbles.

I added the dye. I'm still not sure, if I found a leak. Looking at compressor body with special yellow glasses and light that came with green dye kit. I'm just not sure if that seal is the leak. I see what may be microscopic green dots on compressor body aft of belt pulley. But really I'm not sure if just spec in metal that have variation in color. I'll run AC over time and just keep looking for the dye. I'll also get some other eyes on it.

But for now I charged it with 3 cans and has worked great for last month. For $7 a can, I can just add a can each spring if needed. Over time the leak may reveal itself. But if a very minor compressor seal, it may not be worth doing anything other than a quick charge/top off annually.

Exactly the right approach. I ALWAYS advise folks that IF you have only a small leak....it's just not worth chasing down. Simply top it off once each season and go on with life. If it gets worse...then address it.

 

[2001LC]

Good advise!

 

[nbailz]

UPDATE..."fixed" problem...disregard below, but may be helpful for others so I'll keep it.

Ended up "cheating" and using one of those A/C pro kits that has its own gauge and you just plug into the low side port. Can and a half later and AC is blowing at around 55 degrees with 90 degree ambient temp. I'm convinced something might be wrong with the manifold gauges that i rented, but who knows. Glad I gambled another $35 versus take it in for a A/C diagnosis. We'll see how it holds up.


Rather than starting a new post, thought i'd post here since i'm not in a time crunch. I have an appointment scheduled with my mechanic a few weeks out (earliest they can do), so have some more time to try to diagnose my problem with my AC one last time.

On post #3, there's a good write-up on how to do the job along with the help of my fsm and youtube. Easy enough.

Symptom trying to fix: Ac system is blowing air, but it's not cold

Here's where i'm at:

Before i did anything, i did the on-vehicle inspection and didn't see anything going through the sight glass on the liquid tube. I also didn't see any "static pressures" - both read "0" on gauges.

1. Ran A/C diagnostics from FSM - came up with codes 23 and 47. Further testing seemed to be pretty confusing, but 23 indicates low pressure which i agree with.
2. hooked up manifold to read pressures
3. Pressures on low & high both read 0, so I took that as no freon in A/C system - leak?
4. Hookup and start vacuum pump
5. Open valves 'H' and 'L' on couplers connected on vehicle and 'H' and 'L' valves on manifold
6. Watch pressure go down on 'L' gauge.
7. Pump for about 30 minutes.
8. Close 'H' and 'L' valves on manifold.
9. Pump can be switched off now.
10. Watch for ~ 2 hours to ensure the vacuum is not lost. - Needle didn't move so i took that as no leaks
11. Connect the can tap to the hose removed from the pump.
12. Screw refrigerant can on can tap.
13. Pierce can with the can tap needle and back off needle to allow flow.
14. Use a small screwdriver to bleed the refrigerant hose at the manifold to remove all air from the hose (quick burst, be careful).
15. Start the vehicle, front and rear AC to max AC, open windows. - i didn't do this yet in this step, did it in step 20.
16. Carefully open the 'L' valve on the manifold. Leave the 'H' valve closed!
17. Watch the pressures on the gauges and compare to FSM - this is where it gets confusing
18. Low pressure will slowly built up to about 110 PSI, however, pressure on high side remained at 0.
19. I know i'm not supposed to open the high side when filling through low side, but i did anyway...slowly...and got enough pressure in there.
20. turned on engine, opened high side a little more, AC clutch engaged and started spinning as high side pressure is now ~50-100.
21. with compressor running, freon can open, low side open, high side closed on manifold. i could not get any more refrigerant into the system (i originally didn't have the correct fitting for the auto-seal can, but have it now, so i ruled out that as an issue)

I took the pump back to where i borrowed it and the guy at the counter mentioned that there might be a blockage in my system. At that point i had already called it quits.

Any idea on what i should try to do now? I don't understand why freon isn't entering the system with the compressor engaged, and I'm thinking this is now out of my mechanical abilities (hence the appointment i booked). Thanks for reading

 

[Rpreme]

How often should this AC servicing be done? Once every year? Every 2 years? I have a 98 with front AC only.

 

[2001LC]

When needed!

 

[flintknapper]

How often should this AC servicing be done? Once every year? Every 2 years? I have a 98 with front AC only.

As @2001LC stated "When Needed".

In 'theory' the System should almost never need preventative service. It is a 'closed' system meaning by design...not exposed to atmosphere.

The refrigerants used are not 'consumables' *like engine oil* so under normal conditions do not break down and are not 'used up'. The system lubricant *oil* likewise will last many, many years under normal conditions and if not contaminated.

However, in real life:

• Small amounts of refrigerant leak past seals over time.
• Orings can become compromised.
• Schrader Valves can loosen.
• Past service *done poorly* can introduce air, moisture to the system.
• Desiccant bag in drier can rupture allowing desiccant to migrate, clogging TXV.
• Internal wear/failure of compressor can send metal flakes through parts of the system causing restrictions.

But to answer your question specifically.....when/if you feel the system is not cooling properly *at least 30°F less than ambient temps* at the vents, then its time to investigate. It is possible *indeed likely* that the system is low on refrigerant. BUT other issues *external* might be at play. So check those as well. It is after all a SYSTEM.

• Check to see that your engine cooling fan clutch is working properly
• IF your vehicle is equipped with a condenser fan *for low speed cooling* see that it is working
• Clean your condenser and radiator periodically, the fins can become dirty or clogged over time
• Check your evaporator and evap box for debris, also cabin air filters if so equipped
• Check the air gap on the compressor's magnetic clutch, if excessive it will slip

 

[sleepgsr]

Link to PAG-46 oil amounts and refrigerant amount - https://www.rockauto.com/genImages/52/capacityguide_4season_2020.pdf

 

[Pulgasari]

Might be a more general situation, but I replaced the radiator in my 99 LX 2 weeks ago, and apparently one of the lower AC lines had to be disconnected to remove it, emptying an unknown amount of freon. I believe it was re-connected after installation but I'll double check - I'd say it was probably disconnected for at least 45 mins to an hour.

I was thinking of just getting a recharge kit from an auto parts store (I'm guessing I'd need to get a fairly large bottle to completely top everything up), but I'm not sure how much oil (if any) would be in the system.

1. Is oil loss something I would need to be concerned about when temporarily opening an AC line?
2. Will I damage my AC system by just filling up with a recharge kit, without checking the oil level via vacuum pump or other means?

 

[flintknapper]

Might be a more general situation, but I replaced the radiator in my 99 LX 2 weeks ago, and apparently one of the lower AC lines had to be disconnected to remove it, emptying an unknown amount of freon. I believe it was re-connected after installation but I'll double check - I'd say it was probably disconnected for at least 45 mins to an hour.

I was thinking of just getting a recharge kit from an auto parts store (I'm guessing I'd need to get a fairly large bottle to completely top everything up), but I'm not sure how much oil (if any) would be in the system.

1. Is oil loss something I would need to be concerned about when temporarily opening an AC line?
2. Will I damage my AC system by just filling up with a recharge kit, without checking the oil level via vacuum pump or other means?

No A/C lines need be disconnected to replace the radiator. But IF yours was (for any reason) then ALL of the refrigerant is now gone.

I'm guessing you had someone install the radiator and are now unsure the condition of the system? We really need a bit more information there please.

IF the system was opened (refrigerant hopefully recovered first), reconnected but NOT recharged... then at a minimum...you will need to pump the system down (vacuum pump) before recharging. It is not possible to know how much oil is in the system now because we don't know if it has been serviced before or how the refrigerant was lost.

A good amount of the lubricating oil is suspended in the refrigerant (which carries it throughout the system when operating). Small amounts of oil can pool in the Condenser, Evaporator and Drier. Naturally, the compressor itself harbors the greatest amount (not in suspension).

So yes, adding some oil is likely needed. How much depends on information we don't have.

To be serviced 'properly' at this point....I would recommend you take the vehicle to a reputable shop. Have them install a NEW drier (holds the desiccant), add a few ounces of PAG46, pull a vacuum on the system and recharge with refrigerant. They will want to 'weigh in' the correct amount while also monitoring the gauges (high and low sides) and checking vent temps.

 

[Pulgasari]

No A/C lines need be disconnected to replace the radiator. But IF yours was (for any reason) then ALL of the refrigerant is now gone.

I'm guessing you had someone install the radiator and are now unsure the condition of the system? We really need a bit more information there please.

IF the system was opened (refrigerant hopefully recovered first), reconnected but NOT recharged... then at a minimum...you will need to pump the system down (vacuum pump) before recharging. It is not possible to know how much oil is in the system now because we don't know if it has been serviced before or how the refrigerant was lost.

A good amount of the lubricating oil is suspended in the refrigerant (which carries it throughout the system when operating). Small amounts of oil can pool in the Condenser, Evaporator and Drier. Naturally, the compressor itself harbors the greatest amount (not in suspension).

So yes, adding some oil is likely needed. How much depends on information we don't have.

To be serviced 'properly' at this point....I would recommend you take the vehicle to a reputable shop. Have them install a NEW drier (holds the desiccant), add a few ounces of PAG46, pull a vacuum on the system and recharge with refrigerant. They will want to 'weigh in' the correct amount while also monitoring the gauges (high and low sides) and checking vent temps.

Sure, I went through a mud crossing at an off-road park, the mud stuck to the radiator, and shortly afterwards, the bottom end of the radiator exploded from the main section, leaving a dent in my condenser in the process. Some fellow MUD members towed me back to the campsite, where we replaced the radiator. I was mostly just passing tools around and organizing the parts we had removed, but the guy working underneath let us know that he had to temporarily disconnect the AC system to pull out the old radiator (this was all happening in a campsite parking lot with limited tools, cell service, and time, so we weren't exactly following the FSM). When he disconnected the AC line, a bunch of refrigerant did leak out, suggesting that the condenser was still intact despite tanking a hit from the radiator.

The AC system was working perfectly the morning of the radiator incident, so thinking about it now I'm pretty sure it just needs to be vacuumed and refilled with oil/gas.

Of course, I haven't used or attempted to use the AC since the radiator was replaced, to prevent any further damage to the system.