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740 Service R12 or convert to R134-a

2manyturbos said:
I don't know. I've never tried Duracool. I have used ES-12A in both R-134 and R-12 systems. It gets incredibly cold.
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Alright I?ll look into both. Looks like either ES-12A or duracool will work. So hold a vacuum for 30min-1hr, then evac the system, remove and replace the receiver drier, fill system with duracool and 2 ounces of ester oil.

I will talk to the old lady and order a receiver driver, ester oil, r12 to r134 fittings, and a few cans of duracool.
 
Running Duracool in the Wife's 244. Ice cold out the vents in 80* weather that Oregon sees every once in a summer. Defintely less expensive than R-134a. EnviroSafe is also a good one. Choose your flavor and fill 'er up. Roy does this stuff for a living, I would take his word over quite a few here.

You won't need to purchase any oil if you get Duracool, it comes with a bit in each can that is compatible with PAG and mineral oil. You can get a four seasons receiver/drier from RockAuto for $16.
 
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Thanks for all the words guys! I just had a look under the hood and it looks like perhaps someone has installed r12 to r134 fittings before? I don’t know **** about ac but maybe you guys can tell me. Looks like one of those press fit pieces r134 used instead of a thread on.
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I know it’s the wrong way to do it by just buying the stuff in a can and throwing it in, but I’ve gotten away with it a few times. I have some left over from filling another vehicle and when I put the gauge on the low side fitting I did get a reading (but a low one). I’m hoping the system is just low enough to not kick on. Might throw some Freon in there and see what she does.

Plan is still to evacuate system and fill with duracool (without lube because it has it already).
 
Just filled with enough Freon that the compressor should have kicked on but it didn’t. I’ve jumped ot before quickly to hear it run so I know it isn’t seized. Any other reason it wouldn’t kick on? Fuse number 9 is good.
 
Alright I just jumped the low pressure cutoff thing that connects to the drier and the compressor cycled. Is it safe to leave this jumpered for 10 minutes or so to see if AC gets cold? I had it jumped for about 30 seconds and the compressor didn’t kick off. Don’t wanna over pressurize anything.
 
Added some more R134 and here's what it's doing. Condenser doesn't even get warm and AC doesn't get cold. Any idea what's causing this? Gonna try to grab some real manifold gauges soon.

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The 134a system in my 93 wagon was full like that and was also cycling quickly like that while not cooling. Turned out the system was low on 134 and my gauge was lying about it being full. They hovered out the refrigerant and weighed it. There was a bit less than half of what it should have had in there. Once they filled it and leaked checked it. The system was worked well since then. thankfully 134 service is the cheapest at a shop.
 
I would take it to a shop and have them recover the 134 you put in so you can replace that crusty, tired accumulator and pressure switch. Those pressure switches are known to fail and look just fine, much like the junction block sensor in the brake system.
 
KeizerBrickGuy said:
I would take it to a shop and have them recover the 134 you put in so you can replace that crusty, tired accumulator and pressure switch. Those pressure switches are known to fail and look just fine, much like the junction block sensor in the brake system.
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Accumulator=receiver drier? Gonna throw some manifold gauges on there today.
 
You need to recover the refrigerant and weight it. Guages only tell you part of the story.

When I have a car that won't blow cold, the very first thing I do is recover it so I know if it's a low or overcharge issue. The machine is about $5k.

After I recover it. I vac it down and make sure it holds 29" of vac during and after the procedure.

Then I blast the specified amount of Freon back in there and recheck the system.
 
Bump. I have been reading around and maye there is no high side port on this r12 system. How are you supposed to do proper AC work without reading both sides of the system? I have a set of manifold gauges but cannot even use them.
 
Yeah, Volvo was cool like that. My 93 wagon only has the low side. but it is still good for servicing the system. The refrigerant is sucked out and added via low side. The vacuum is drawn on the low side so you should be fine.
 
PromiseRing said:
Bump. I have been reading around and maye there is no high side port on this r12 system. How are you supposed to do proper AC work without reading both sides of the system? I have a set of manifold gauges but cannot even use them.
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I'm pretty sure the high side port is on the back of the compressor.
 
dl242gt said:
Yeah, Volvo was cool like that. My 93 wagon only has the low side. but it is still good for servicing the system. The refrigerant is sucked out and added via low side. The vacuum is drawn on the low side so you should be fine.
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Yes but every source I?ve found has said that in order to do proper work, high and low sides should be considered.
 
PromiseRing said:
Yes but every source I?ve found has said that in order to do proper work, high and low sides should be considered.
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That is true if the compressor is an unknown. If you are reasonably confident in your compressor then using just the low side for service will work. I've had mine worked on several times and the shop didn't say anything. They may use some type of adapter that I don't know about but my system is still stock with only the low side port.
 
dl242gt said:
That is true if the compressor is an unknown. If you are reasonably confident in your compressor then using just the low side for service will work. I've had mine worked on several times and the shop didn't say anything. They may use some type of adapter that I don't know about but my system is still stock with only the low side port.
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I’m not confident on anything in this car. If I have a shop evac the system and hold a vacuum, can this be done on just the cold side? I’m really hoping the compressor still compresses. She is needing cold ac asap.

Should I also replace the orifice tube on this 740? Not sure where it’s located or if it’s bad but it’s a very very cheap part.
 
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