Automotive Air Conditioning Information Forum

Okay sorry, here’s another question.

As for the pag oil, I couldn’t find the 46 in store so I’m checking another store (Napa) tomorrow, or ordering it online. We’ll see.

For the flush, I think I found some of the disposable stuff in a pressurized can. I would use my own air compressor and a gun+canister but as rarely as I do ac flush, I don’t think it would make monetary sense.

Here’s the compressor, no idea if there’s oil in there or not but I don’t think there is. I’m assuming I remove this top cover and add the correct amount of oil.

Still can’t find an r134a specific RD.

Expansion valve is the wrong one but I don’t think the original is clogged. Perhaps since the evaporator core is new, they will both be different sizes and will be correct for each other.

https://i.imgur.com/hy2tzcp_d.jpg?maxwi ... ity=medium

Hey guys. I’m adding oil to the compressor and I cannot get t to take even 4oz. I dumped the mineral oil and flushed, then tried to add 4oz of pag 46. It seems I only drained about 2oz or so of mineral oil. What to do?

If you haven't already done so, crank it over by hand as you're pouring the oil slowly jnto the ports. That usually helps. After you get all the oil in, crank it over another 10 or 12 revolutions so that it doesn't 'slug' when you first run it.

If you can get 4 ounces in the compressor, I'd then put 1-1/2 ounces each in the evaporator and condenser and 1/2 ounce in the R/D.

Hey everyone. So, got the truck all buttoned up today. Ended up actually being the correct expansion valve in the mail so that’s good.

Blew all the lines out with some $17 one-time-use cans from the auto parts stores (worked well), and then used compressed air to clean the residue out as best I could.

Installed all the new parts, then had a question about mounting the TXV bulb. I ended up mounting it where the factory one was, but was unsure of how to fasten it to the low side pipe. I ended up using some cork insulation tape as per recommended on here. Made a nice seal and hope it holds up well.

I vacuumed the system for over an hour and a half and was only able to pull about 26"Hg. Wonder why? Again pressed for daylight/time, I filled the truck with 23oz of r134. Oh yeah, for oil I had put 4oz in compressor, 1/2oz in R/D, then maybe an ounce in he condenser. I forgot about the evaporator I added some oil in the yellow manifold gauge line so I’m hoping there’s sufficient lubrication. I really needed better means of measuring the oil but we shall see how long it lasts. Anyway, 23oz of r134 in, and my gauge readings were, IIRC, about 35psi low, 250-275 high (clutch fan engaged. Before it engaged they were nearing 300psi so i put a fan on the condenser and they immediately dropped back down.) But unfortunately vent temps were only about 48-54. Closer to 60 at idle. And it’s only 75F out! So it’s not the coldest, but works none the less. Let’s see how it performs when it’s 100F out. Am I expecting too much from the old style condenser?

Thanks again for everyone’s help!

One more thing! Upon removing the R/D, I noticed I could shake it and hear all the little silica balls loose in there. I was able to turn it upside down and dump some out. Also I could not blow my breath through the condenser but I could with compressed air. So surely both of those things were partially clogged.

Bump. Just wondering about my previous posts please. Ac is still working though.

Your flushing-the-lines process sounds pretty good. I would think that they're clear of any oil and debris now. Glad you didn't use mineral spirits.

Based on the low-side pressure, the TXV seems to be working well the way you installed it.

I'm concerned about the vacuum reaching only 26 InHg, though, which isn't really sufficient for a good evacuation. Several things could cause that. Among them: Are you sure your manifold gauge set and hoses aren't leaking? And what kind of vacuum pump are you using? If it's the compressed-air type, they usually can't achieve the 29 InHg-plus that we like to see. After you closed the handwheels on the manifold gauge set and shut off the vacuum pump, did the vacuum that you were able to achieve hold steady? If not, there might still be a leak in the system somewhere.

Your refrigerant charge of 23 ounces sounds about right for this R-12 to R-134a conversion. The oil amount sounds a little light given the original spec but will probably be okay. The low-side pressure of 35 PSI should give an evaporator temperature of about 40 degrees and a center vent temp in the high 40's, which is essentially what you reported. The high-side pressure is elevated, though, at an ambient of only 75 degrees. At that temp, I would expect to see high-side pressures in the 180 to 190 PSI range.

An elevated high-side pressure usually points to an airflow problem. Do this simple test. Mist water on the condenser with a garden hose and nozzle while watching the high side. If the pressure drops into or near the preferred range, you have insufficient airflow over the condenser. To correct it, check to ensure that air isn't bypassing the condenser. Are all the foam seals between the condenser and radiator in place? If the truck originally had a fan shroud, is it still there and intact? Double-check the fan clutch to ensure that it's roaring at a fast idle with the A/C on. Is a plastic bag or other debris partially blocking airflow between the condenser and radiator? Was there any plastic film on the new condenser's core that you forgot to remove?

If the high-side drops considerably lower than the preferred range (while taking into account the ambient temperature), then you probably need to charge it a little more...maybe an ounce or two. Compared to late-model factory systems that take a very specific amount of refrigerant, conversions like this are hardly ever exact and are somewhat experimental.

As for the old receiver/dryer, you shouldn't be able to pour out any of the desiccant beads. If you can, the desiccant sock has broken open inside the R/D and has sent at least some of the beads downstream toward the condenser and TXV. No need to worry about that now, though, since you've replaced those parts with new and thoroughly flushed the high-pressure line.

Thanks for the reply John. My neighbor drove her truck to the airport the next morning and told me the ac worked still (so that’s good). She has been gone for a while so we will see if it still works when she returns.

I had vacuumed the system for about 1 hour or maybe 1.5 hours with a vacuum pump I rented from AutoZone. This is the same type I’ve rented there many times before and have always been able to achieve 29-almost 30 in Hg on other vehicles (Including her Toyota, before the new system). Considering I had removed every single possible connection in the system, the likelihood of a leak is higher. When I vacuumed it for 1-1.5 hours, it was 10pm and she was leaving the next morning for the airport, so I was in a hurry to get some refrigerant in the system.

If she reports back that the ac stopped working, I can only assume it’s because of a slow leak. Now that I think about it though, since the system was open for a few hours, isn’t it much more difficult to get that 29-30 in Hg? On a system that hasn’t been exposed to outside air, it seems to go into vacuum much easier. I’m wondering if I did a longer vacuum and achieved that number, if vent temps would be cooler.

As for the airflow, this vehicle has a brand new fan clutch that operates as it should. It whooshes upon startup but then disengages after 30 seconds or so. This is normal and unfortunately it’s just the nature of the beast. That’s why most mechanical fan clutch equipped cars will also have an electric 'auxiliary' fan for ac. Because at idle that clutch doesn’t move much air until the radiator is releasing hot air. I have previously talked to her about having me install a pusher/puller efan on the condenser to keep pressures low.

All gaps are sealed how they were from the factory. Whether or not it’s sufficient is a toss up. Surely it can be improved upon if I were to 100% seal all gaps between rad and condenser. The fan shroud is also in place.

However, as stated earlier i think (or maybe on another forum), I did solve her ‘overheating’ problem with the new clutch. When I first charged her ac, coolant temps would climb at idle. They are much more steady now.

Opportunity for improvement/learning curve for next AC service:
Evidence of a good compressor is to pump up to the PRV (pressure relief valve) pop off pressure about 420 psi (the first time) and blow out oil with leak dye and R-134a.
hotrodac