R12 Charging questions

[JDMMA70]

Ok guys i have a few questions regarding the recharge of the R12 system. First i do have a few 12oz cans of R12 left so this isnt about where i can get it. Second the system is completely empty as i had to replace the compressor with one of my spares, i used the recovery machine at work (thats all it does it wont charge it anymore). My question is how much R12 will need to be in the system before the a/c clutch will engage i made the mistake last night and ended up wasting a can because one of the older techs told me it shouldve engaged as soon as the charge line was opened. Please note i was not the one charging the system i had one of the older techs with a set of guages do it for me, and im just going by what he said. So before i even try charging this again and wasting more valuable R12 how much needs to be in the system before it turns on. If its not what should i look at. Ive checked the fuse, and the relay. The relay has continunity so it would seem. If those two are fine then is it the compressor?

Thanks for your time
~JDMMA70

 

[jetjock]

Sounds as if that "tech" is pretty clueless or maybe you misunderstood something.

Enough to satisfy the low pressure cut out. Around 23 psi. You should be able to add that much with the engine off. Might have to heat the can. Or jump the compressor on for a short time. Or charge with liquid. Lots of ways to do it.

Not sure what you meant by "wasted". If it went in there it should still be in there...

 

[JDMMA70]

Sounds as if that "tech" is pretty clueless or maybe you misunderstood something.

Enough to satisfy the low pressure cut out. Around 23 psi. You should be able to add that much with the engine off. Might have to heat the can. Or jump the compressor on for a short time. Or charge with liquid. Lots of ways to do it.

Not sure what you meant by "wasted". If it went in there it should still be in there...

His side can tap leaked like no tomorrow, and he recovered it out of the system saying my compressors bad, this resulted in some arguing and him giving me $40 to compensate for my lost refridgerant.

Now having you here jetjock giving your wisdom makes me not want to let any of these guys near my car again. Im going to find someone more qualified to do this for me.

Question two: Are you saying i can add at least a can with the engine off and then start the car when i start with the second can (using 12oz cans) and using a side can tap that doesnt leak. Can i use one of my top can taps (the one that pokes the hole in the top of the can?)

 

[CyFi6]

Yeah, the tech really should be charging the system by weight if he wants to get exactly the right amount of refrigerant in the system. I have filled my system before from a vacuum state with cans and I didn't have to jump the compressor, the can had enough pressure to close the low pressure switch (granted it wasn't R12 at the time), I had the car running and AC on high, once enough pressure was in the clutch engaged itself, then the low side pulled in the rest of the charge.

 

[jetjock]

Not a big fan of side taps for several reasons and small cans can be a pain. Still, one should be enough to close the switch depending on volume. Charge until you hear the clutch click. The engine does not have to running for that to happen.

Again, there's lots of ways to skin this cat but if you're going to have someone else do it I won't go into detail. What Cy said is basically correct. It's not that hard but the bottom line is to find someone who knows what they're doing.

Myself, I typically use a electric charging cylinder and determine final charge by superheat. Fancy gear isn't needed though. Charge until the bubbles disappear and add bit more beyond that. That works only with R12 though. Which reminds me: if the system was empty for a long time you should have replaced the receiver/dryer.

 

[JDMMA70]

Not a big fan of side taps for several reasons and small cans can be a pain. Still, one should be enough to close the switch depending on volume. Charge until you hear the clutch click. The engine does not have to running for that to happen.

Again, there's lots of ways to skin this cat but if you're going to have someone else do it I won't go into detail. What Cy said is basically correct. It's not that hard but the bottom line is to find someone who knows what they're doing.

Myself, I typically use a electric charging cylinder and determine final charge by superheat. Fancy gear isn't needed though. Charge until the bubbles disappear and add bit more beyond that. That works only with R12 though. Which reminds me: if the system was empty for a long time you should have replaced the receiver/dryer.

Thanks for your advice jetjock its well appreciated. As far as side taps go do you prefer top taps i have one of those brand new in the packaging still. The system was recovered last week as i replaced the compressor then i put vacuum on it and attempted to have someone charge it yesterday. At this point now i think im just going to preserve the R12 i have left get a brand new compressor from denso just to play it safe. I have a brand new drier ready to go on. Im trying to figure out how exactly it comes off theres not enough room for a wrench i think i need a special kind of wrench for this.

Is there anything else i should consider besides finding someone with a bit more brains? I really wanted to learn how to do this myself but it seems that wont happen unless i have someone who actually knows what they are doing.

 

[jetjock]

Top tap is fine. Funny how those little cans kept shrinking. I remember when they were 16 oz, then 14 oz. Bastards. Makes charging a hassle especially on the larger systems of older cars. It's why I use 30 pounders.

Even the dealer's comps are rebuilds. That's how I'd go if I was going to buy one. I did and it was still working fine 15 years later. Expect to pay a bit more but it'll be worth it. A brand new one is overkill but it's your money.

To do it right you should flush the system, replace the O rings, change the R/D, add the correct amount of a oil (taking into account how much came in the new compressor), evac, leak test and charge. Or let a shop evac and charge after you've done all the grunt work. Put a new belt on while you're at it.

The only person needed to learn this stuff is yourself. The internet is more than a global pornography network you know. There's also the Hanyes Auto AC book found at the local car store. While I'm not a fan of Haynes repair manuals their AC book is decent for noobs.

Get your 609 license online for $20. Buy a manifold gage set, a cheap(ish) vac pump, and maybe a scale. Those and something to measure temperature with are all you'll need for most work.

And stop quoting my entire posts. They're long enough without having to be read twice

 

[CyFi6]

It's not that hard but the bottom line is to find someone who knows what they're doing.

True that... I messed with mine for a long time before I admitted I was better off having the pro's do it. Though in the end they didn't really make my system work any better, I guess I just had higher expectations of what seems to be a rather small/weak system.

Charge until the bubbles disappear and add bit more beyond that. That works only with R12 though. Which reminds me: if the system was empty for a long time you should have replaced the receiver/dryer.

Is there ever a case where bubbles being present are normal with the system running? I see bubbles in my sight glass all the time when it decides to blow warm, usually lower engine speeds or when its heat soaked, but when I told my shop about it they insisted that bubbles are normal even though the system is R12. My car has spent hours there, and the AC is still rather weak, they said they have done all they can on it though.. what can I say, it works great revving it to 2500 RPM with the hood open and in the shade for 10 mins...


BTW I don't mean to thread jack, just thought I would squeeze some more info out of JJ while I had the chance

 

[jetjock]

For R12, no. Full time foaming is usually an indication of low charge. In a fully charged R12 system foaming normally occurs only after the compressor stops and then only briefly. R134 is a different story. It's why those systems typically don't have sight glasses.

You live is a tough climate though. I would say the system is being taxed except I've driven in similar environments and not had problems. Could be you're seeing the compressor shut off for high side pressure or the condenser may need replacing. If so parallel flow would be the way to go.

 

[CyFi6]

You live is a tough climate though. I would say the system is being taxed except I've driven in similar environments and not had problems. Could be you're seeing the compressor shut off for high side pressure or the condenser may need replacing. If so parallel flow would be the way to go.

I've only seen the compressor shut off from high side pressure when idling for a long time, and by then my vent temps are laughable. When the system is blowing mildly cold, the compressor stays engaged 100% of the time (I can feel the drag if I'm driving and I can see it on my vacuum gauge). Anyhow, the biggest issue is that it takes eons to get cold if the car has been sitting outside in the sun, even worse if the engine bay is hot. It makes me sad when I get in a modern car and get blasted with ice cold AC a minute after I turn it on.

Condenser has been flushed, so only thing left is to replace. This is about how it goes every year...
Summer comes, crap, my AC sucks, should I replace the condenser with a parallel flow? Its too damn hot to work on my car...
Winter comes...I have better stuff to spend my money on right now...
And the cycle repeats.

 

[jetjock]

Flushing is usually not all that effective on aged condensers. If you do replace it might as well upgrade to parallel flow. Iirc someone on here found a direct fit one. Something is wrong though.

Could also be low air flow or a dirty condenser exterior. Refrigerant could be contaminated. Hard to say without actually going hands on. On the other hand I'm a bit hesitant to second guess any shop in PHX. They tend to know what they're doing.

At least it's a dry heat

 

[3p141592654]

A dry heat with some dust! :icon_bigg

Bubbles in the high-side is vapor going to your expansion valve. Expanding a vapor is pretty useless as far as making your evaporator cold.

Have you verified that your expansion valve is working? Toyota did recall the TXV on the mk3 supra. The campaign is long over, but you should verify it was done. As JJ said, measure the superheat and you will know if the valve is working. Also measure subcooling. These are numbers you absolutely need to validate if the system is working, and if not, why not.

 

[CyFi6]

I know 3p you have helped me a lot in my previous threads, all I really need to do is measure exactly what you told me to measure. I should really pick up some thermocouples and finally do it.

I figured the vapor entering the expansion valve was no bueno but being an amateur my arguments are not very substantial when talking to professionals. Who knows, maybe they have a better idea of whats going on and just told me its normal to get me to stop bugging them.

I won't go into it much here but the whole system is rebuilt with
Rebuilt compressor
Fully removed and flushed lines, evap, condenser
New TXV properly mounted sensing bulb
New seals all around
New flexible hoses
New receiver dryer
Proper fill of mineral oil
Fan shroud, undercover etc all cooling items in place
New OEM Tundra clutch fan (driving around town in the summer with this thing it is at full engagement basically all the time)


Anyways I know what I've got to do to check the system out, now I just need to stop being lazy and figure it out.

BTW sorry JDM for completely veering your thread in a different direction.

 

[jetjock]

Hmmm. I won't go into why but truck fan clutches on cars are a bad idea. You would not be the first to make the tundra mistake.

 

[CyFi6]

Hmmm. I won't go into why but truck fan clutches on cars are a bad idea. You would not be the first to make the tundra mistake.

Lol .

 

[jetjock]

No time to type it all out but I'll repeat something I've said before about all sorts of things fan related: more CFM is not necessarily better. Has to do with residence time. Iirc didn't/don't you also have cooling problems?

 

[CyFi6]

I'll repeat something I've said before about all sorts of things fan related: more CFM is not necessarily better.

Yes I have seen you say this many of times but without explanation.

I haven't had a single cooling system problem since I got rid of my aftermarket gauge and installed a stock one . I didn't put the Tundra clutch in all that long ago, if anything I have noticed better results with it compared to my very new GTE clutch.

 

[JDMMA70]

Im buying my own set of manifold gauges is there any benifits or differences between brass and aluminum guages?
http://cgi.ebay.com/ebaymotors/ws/e...akeTrack=true&ssPageName=VIP:watchlink:top:en
or
http://cgi.ebay.com/ebaymotors/CPSM...t=Motors_Automotive_Tools&hash=item4cf14cb0a8

Is there anything special i should do when i first charge it with the new compressor? Or just charge through the low side as normal till i hear the clutch click and then turn on the vehicle and a/c?

Thanks again for everyones advice.

 

[jetjock]

Buy the best you can afford. And yes, just do as you said. Make sure the can stays upright. If the gage reads more than 30 psi and the clutch hasn't come on stop and find out why.

Edit: Make sure you understand how the valves on the gage set work. Remember, they don't control the gages. They connect the low and high side hoses to the center hose. Don't open the red knob when charging or very bad things could happen...

 

[JDMMA70]

Do toyota reman compressors and brand new denso units come preoiled with mineral or ester? It doesnt.say.and does anyone recommend changing the oil oil out when I get the new one?