Thread: Slow a/c on D4

I don't use pag in that application..I use a universal or a hydrocarbon oil. I've seen plenty of dead compressors from hychill and it's variants

My compressor is 288,000km. I guess I need to bite the bullet

Originally Posted by DiscoJeffster

My compressor is 288,000km. I guess I need to bite the bullet

Mine 240,000km and never missed a beat and never touched the gas yet still very cool

Originally Posted by josh.huber

I don't use pag in that application..I use a universal or a hydrocarbon oil. I've seen plenty of dead compressors from hychill and it's variants

I had a look at the hychill documentation years ago, and noticed they appear to recommend severe undercharging. I can understand why in that HCs reject to the condenser better and so you don't need the extra volume for subcooling, but it leaves bugger all reserve, so when the system leaks a bit it winds up severely undercharged, oil logging the evap and starving the compressor of lubrication.

They recommend ~30% of the charge. Example, the Golf specs 525g of r134a. Hychill recommend 160g charge.
At 25c, 525g of r134a is ~420ml. At 25c, 160g of HC is ~324ml. So right off the bat the thing is pretty seriously undercharged. It needs about 200-210g (~40%) for the equivalent volume.

Yeah, sure it'll work, but it impacts lubrication leading to grey death. On the other hand, Hydrocarbons transport lubricants so much better than HFCs that most lubes seem to work if they are circulating.

Ideally I'd pull the compressor and change the oil, but for a short (ish) term test it's not likely to be an issue. Plus the compressor on the golf is only slightly harder to change than a TDV6 HPFP. I've never had an issue with PAG or POE and HCs but maybe I've just been lucky.

I do wish people would speak English on this thread

Originally Posted by BradC

I had a look at the hychill documentation years ago, and noticed they appear to recommend severe undercharging. I can understand why in that HCs reject to the condenser better and so you don't need the extra volume for subcooling, but it leaves bugger all reserve, so when the system leaks a bit it winds up severely undercharged, oil logging the evap and starving the compressor of lubrication.

They recommend ~30% of the charge. Example, the Golf specs 525g of r134a. Hychill recommend 160g charge.
At 25c, 525g of r134a is ~420ml. At 25c, 160g of HC is ~324ml. So right off the bat the thing is pretty seriously undercharged. It needs about 200-210g (~40%) for the equivalent volume.

Yeah, sure it'll work, but it impacts lubrication leading to grey death. On the other hand, Hydrocarbons transport lubricants so much better than HFCs that most lubes seem to work if they are circulating.

Ideally I'd pull the compressor and change the oil, but for a short (ish) term test it's not likely to be an issue. Plus the compressor on the golf is only slightly harder to change than a TDV6 HPFP. I've never had an issue with PAG or POE and HCs but maybe I've just been lucky.

Hey Brad, I agree with the under charging. Hychill now make a oil for there product. I have always used a oil from Ashdown that was called extol. I did read once that the hydro carbons were not mixing with the original oils and pooling in condensers and not traveling through the system and that was why the compressors fail with HC refrigerants in them

Originally Posted by josh.huber

Hey Brad, I agree with the under charging. Hychill now make a oil for there product. I have always used a oil from Ashdown that was called extol. I did read once that the hydro carbons were not mixing with the original oils and pooling in condensers and not traveling through the system and that was why the compressors fail with HC refrigerants in them

Ta for the headsup on Extol. The data sheet reads _exactly_ like the datasheet for the Hychill SRO500. I've also heard people talk about hydrocarbons not mixing with the other oils used, but given PAG oil is used (and was apparently originally designed) for hydrocarbon compressors (not in A/C use but oil and gas) I'd be very surprised. Also, when they discontinued using R11 as a flush, pretty much all the newer flushes are hyrdocarbon. So it'd be pretty silly to use something as a flush that wasn't capable of sweeping pretty much anything out of a system quickly and efficiently. Even the Extol flush is pretty close to Shellite and n-Heptane.

I've never seen oil pooled in a condenser, although I suppose with a gross undercharge it might be possible. I've certainly seen oil logged evaporators.

I think the bad rap hydrocarbons get is mainly due to poor workmanship. You get a car with a leak, gets taken in to "dodgy brothers automotive" with a "please make it work I don't have much money". They "gas 'er up" and it works for a while, but following the Hychill manual it's undercharged to start with. By the time it's noticed that it's not working again most of the oil is logged in the evap and the compressor is grinding itself to aluminium dust. One or two horror stories get around and suddenly it's the refrigerants fault.

Couple that with r134a being **** at transporting even oil it's compatible with, it takes a r134a system a lot longer to evacuate the oil from the compressor. Hydrocarbons will sweep pretty much any oil around pretty quickly, so they'd dry the compressor a *lot* quicker.

I will say my theory on my wifes golf is the PAG is starting to turn and gumming up the PCV. I checked a bit of oil when I removed the 134a and it's not supposed to be that colour.

As 134a is not great at shifting lubricant the whole works gum up and take ages to get moving. By the time I'd finished charging it up with HC, the AC was back to full performance and I now have a high "Wife Approval Factor". Not delay and it's cold before she's backed out of the driveway. As I think the PAG is turning I'll order some Extol and the flush and give it a good run-through when it starts to cool down after Easter.

We had a good run using it in mining excavators in Africa in extreme heat. We didn't gas off weight but. Mainly off pressures and evap performance.
Was used to lower head pressures due to a poorly sized aftermarket system. I just use extol in everything. I'll run 134a plus in the D4 with a new compressor after a flush. Not looking forward to removing the compressor.

For everyone else with a dodgy compressor at the moment. I have found setting both sides at LO. And controlling the temps with the manual fan speed works best at faster cooling and keeping it cool without it fading away.