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R-12 auto A/C tech in chit chat

[486] said:
oil amount is really tricky, just because of how it pools basically everywhere so you can't exactly drain it all out to get a repeatable baseline

if you flush the system with solvent and really drain the compressor out good (especially if it is brand new)
add 6oz

Too much and it won't cool right, ran into that with my VW, where I'd add an ounce or so every time I'd top it up, eventually there was too much and it wouldn't cool until I yanked the compressor and dumped some out
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Everything is new so I have that for a baseline. Put 2 of the 8 oz. (corroborated from two or three service manuals) in the new evaporator as I was buttoning everything up.

Grrr. Wrong fittings top and bottom. Back it goes. This is #2. Thought about reusing the old evaporator but figured I'd take a chance and order one from O'Reilly's as I see they carry a different brand.

So maybe I'll just keep it at 6 oz total?
 
plym49.2 said:
Everything is new so I have that for a baseline. Put 2 of the 8 oz. (corroborated from two or three service manuals) in the new evaporator as I was buttoning everything up.

Grrr. Wrong fittings top and bottom. Back it goes. This is #2. Thought about reusing the old evaporator but figured I'd take a chance and order one from O'Reilly's as I see they carry a different brand.

So maybe I'll just keep it at 6 oz total?
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make sure you get as much oil out of the compressor as you can, they ship with "god only knows how much and what kind" of oil in them
 
I'm doing one today R4 pancake compressor, 6oz oil. Everything is new or flushed.
Evaporator 3oz
Condenser 1oz
R4 Compressor 2oz
1000042390.jpg
 
[486] said:
the accumulator is the filter/dryer can
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Yeah I realized that I messed that up afterwards, but the stupid instructions are not clear.
There was NO oil in the old compressor :homer:.
I put
2oz in the compressor
2oz in the accumulator
1oz in the condenser
2oz in the evaporator

I drew a vacuum on it and will check it in the morning.
 
So I am pissed off. Really pissed off.

Finally obtained all the correct parts. Put it all together with new o-rings. Lubed the rings and the threads on the fittings and the glands with r12 mineral oil. Put 6 oz total oil in distributed pretty much as above (compressor had a tag that said not to add any additional oil). Everything new except the metal u-tube that connects the drier to the evaporator output and the metal liquid line (contains the orifice tube) because NLA.

Pumped it down to 26". Held fine.

Today I started adding r12 and noticed that the high pressure seal on the compressor was leaking under pressure. It held under vacuum. Replaced both with the old seals. Pumped it down again but could only pull 22-24". But today was hella hot.

Charged it again and even after a pound went in the compressor was not starting. Jumped the pressure switch on the drier and the compressor ran, nice and quiet.

Got it up to 2+ lbs (target is 2.5) and the return into the compressor was frosty, so that was enough. D/C'd the gauges. Still won't run unless the pressure switch is jumped. But now it is not getting anywhere near as cold.

Disgusted. Packed it in for the night.

I'll order a new switch but AFAIK the old one was good. But WTF is wrong this time? Maybe my gauges suck (cheapo Amazon)? Leaking somewhere (I don't have a leak detector device)?

Road flare behind the front seat? I have really had enough.
 
good luck finding an r4 compressor that works anymore. hope yours is good. I convert to sanden when I"m doing one now.
I've had lots of problems out of the newer switches as well.
 
V30crewcab said:
good luck finding an r4 compressor that works anymore. hope yours is good. I convert to sanden when I"m doing one now.
I've had lots of problems out of the newer switches as well.
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It's a rebuilt R4. Actually seems OK.

I am wondering if I did not charge it properly or if my gauges bring the suck. But did not see any evidence of a leak to explain why it went from frosty to luke warm in a few mintes.
 
M92PV4U said:
1000042400.jpg
1000042401.jpg
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A lot of that looks familiar. Yu have better gauges than I do and you probably have a better pump. Mine is the cheapo HF unit that someone gave me.

How long do you run the pump? I run mine until the gauge stabilizes and when I see a light mist coming out of the pump outlet - I assume that is when some oil is misting out.

How far do you open the low side valve when charging/pulsing? Does it have to be opened all the way?
 
plym49.2 said:
A lot of that looks familiar. Yu have better gauges than I do and you probably have a better pump. Mine is the cheapo HF unit that someone gave me.
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I'm using yellow jacket gauges and a robinair vacuum pump.

plym49.2 said:
How long do you run the pump? I run mine until the gauge stabilizes and when I see a light mist coming out of the pump outlet - I assume that is when some oil is misting out.
Click to expand...
It says you should vacuum the system for :30 to clear any moisture, so that is what I did.

plym49.2 said:
How far do you open the low side valve when charging/pulsing? Does it have to be opened all the way?
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I don't open it much, if the compressor starts rattling while adding freon, that is too much.

Keep in mind though, I'm a water well driller working on a/c.:laughing:

I ended up putting 2lb 6oz R134
 
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My pump got it down to 28" first time through. I left it running for about an hour. It held vacuum for several hours; when I filled the system I noticed that the compressor manifold seals leaked under pressure but held vacuum. Or maybe because things heated up from the motor running?

Replaced them and now this, per the above.
 
Are you sure that you have the correct oring sealing washers? Gm has at least three different styles.
 
M92PV4U said:
Are you sure that you have the correct oring sealing washers? Gm has at least three different styles.
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Pretty sure. I have the ones that are different thicknesses. The larger diameter one is thin, and the small diameter one is thick. The compressor ports are different depths and with the manifold it all sits even with a thin amount of edge showing (therefore, should be clamping).
 
plym49.2 said:
Pretty sure. I have the ones that are different thicknesses. The larger diameter one is thin, and the small diameter one is thick. The compressor ports are different depths and with the manifold it all sits even with a thin amount of edge showing (therefore, should be clamping).
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The truck I'm working on is a 89 full size blazer. It took the green and gold washer. The red and silver one were too thin.
 
Mikel said:
In a mini! What A/C system is that? How does the R152A do?
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"Factory"
But it sure looks like a vintage air add on system. Completely separate air box, controls and vents. Mini is 1993 from Japan. Fuel injection and AC.
152 works fine and is a better option than tearing this whole thing apart to replace all the shit it would need to run 134. It has ester oil in it so the 152 plays nice with the oil.
 
Some tips that may help:

PAG oil requires HNBR o-rings. These used to be all colour coded green but some are black these days according to workshop manuals.

R290 is refrigerant propane. Like BBQ propane but cleaner.
R600 is refrigerant grade butane. It's a heavier gas than R290/propane.

R12 and R290/R600 transfer heat way better than R134 and R1234ZYF or whatever the new grade is called.
To get a R134+ system to cool well the heat exchangers have way smaller passages to expose more surface area. If you use R134a in an R12 system the cooling capacity drops a lot because you can't get the heat in/out of the refrigerant fast enough.
If you change out both evaporator (inside dash) and condensor (out the front) your R134a performance will be good.

R134a also evaporates out through hoses etc. They can lose 10% charge a year in a healthy system. They will lose it faster if you have old R12 hoses.

R290/R600 mix is interchangeable with R12 as far as all performance goes, but the gas weights are much lower. The media claims of explosions are scaremongering bollocks. There is more gas in an aerosol can.

Vent cooling temp isn't the same thing as cooling capacity but they are linked.
Many systems run a thermo switch on the evaporator to prevent it icing up. These can kick out about 2-5C (35-42F) to stop you making ice in humid weather.
I had a car (Nissan) which couldn't get below 10C vent temp which made it really hard to keep cool. I hacked into the thermistor to switch in other resistors on a dial so it could do stock (10C), cold (5C) and sub zero out the vents.
This worked great but the switch was necessary. Because sub zero would freeze your hands into claws after a while.

That thermoswitch on the evaporator wasn't on any of the wiring diagrams.

Lastly. If you have an engine driven fan your system will run hot and give high pressures when stationary testing.
 
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Some forward progress today.

I noticed that one of the fittings on the condensor (the high pressure line) was not tightened
Dougal said:
Some tips that may help:

PAG oil requires HNBR o-rings. These used to be all colour coded green but some are black these days according to workshop manuals.

R290 is refrigerant propane. Like BBQ propane but cleaner.
R600 is refrigerant grade butane. It's a heavier gas than R290/propane.

R12 and R290/R600 transfer heat way better than R134 and R1234ZYF or whatever the new grade is called.
To get a R134+ system to cool well the heat exchangers have way smaller passages to expose more surface area. If you use R134a in an R12 system the cooling capacity drops a lot because you can't get the heat in/out of the refrigerant fast enough.
If you change out both evaporator (inside dash) and condensor (out the front) your R134a performance will be good.

R134a also evaporates out through hoses etc. They can lose 10% charge a year in a healthy system. They will lose it faster if you have old R12 hoses.

R290/R600 mix is interchangeable with R12 as far as all performance goes, but the gas weights are much lower. The media claims of explosions are scaremongering bollocks. There is more gas in an aerosol can.

Vent cooling temp isn't the same thing as cooling capacity but they are linked.
Many systems run a thermo switch on the evaporator to prevent it icing up. These can kick out about 2-5C (35-42F) to stop you making ice in humid weather.
I had a car (Nissan) which couldn't get below 10C vent temp which made it really hard to keep cool. I hacked into the thermistor to switch in other resistors on a dial so it could do stock (10C), cold (5C) and sub zero out the vents.
This worked great but the switch was necessary. Because sub zero would freeze your hands into claws after a while.

That thermoswitch on the evaporator wasn't on any of the wiring diagrams.

Lastly. If you have an engine driven fan your system will run hot and give high pressures when stationary testing.
Click to expand...
Do green o-rings work with R12/mineral oil?
 
87manche said:
"Factory"
But it sure looks like a vintage air add on system. Completely separate air box, controls and vents. Mini is 1993 from Japan. Fuel injection and AC.
152 works fine and is a better option than tearing this whole thing apart to replace all the shit it would need to run 134. It has ester oil in it so the 152 plays nice with the oil.
Click to expand...
japan is wierd, they mandate A/C for their domestic market cars, so they can have defrost

My datsun pickup came with a similar dealer addon ac
it was a completely separate underdash box that spanned the width of the cab with vents and a condenser and blower
it was all busted up and crumbly plastic so I pitched it in the trash
it was probably worth something to someone, oh well
"it was"
 
Some forward progress today. Noticed that the high pressure line fitting on the condenser was loose. Tightened it up, pumped it down again, same 24+". I am going to call that good.

Tomorrow will change the pressure switch on the drier and pump it dwn again and refill it.

Now.....

What is best practice for filling? I have heard high side/liquid/engine off and low side/gas/engine running.

I do not have anything that will connect to the high side fitting. It seems to be an R12 quick-connect and I don't have anything that will.

I would normally do low side/liquid/motor running and a bit at a time.

I have a scale so can add the 2.5 lbs it calls for.. I will likely add some dye as well.
 
87manche said:
"Factory"
But it sure looks like a vintage air add on system. Completely separate air box, controls and vents. Mini is 1993 from Japan. Fuel injection and AC.
152 works fine and is a better option than tearing this whole thing apart to replace all the shit it would need to run 134. It has ester oil in it so the 152 plays nice with the oil.
Click to expand...
poe (ester) oil is fine with 134, too
probably just an orifice tube

whatever, run what you brung and all that
 
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