New AC R-1234yf - Is toppin off smart?

[dihi22]

Hi folks. AC service is pretty dang expensive. I was wondering after 30 or 40k if its wise to shoot a few oz of topping off refrigerant into the AC system.

All Ac systems will bleed off some refrigerant, and I'm not afraid a couple of oz would over fill it. But i do know that running it on the low side might wear out the compressor, and when that sucker goes the only reliable repair is also doing at least a new condenser. How can any ac tech ever assure that the bearing or grenaded wear material was flushed?

I have an AC pro can of r-1234yf sitting around. I used about half of the 7 oz bottle on my '18 civic (which i traded in the following year). The civic had the tell tale black spots on a few places on the condenser which showed the PAG oil marks of leakage. The system didn't have a noticable drop in performance, but after a few ounces of the ac pro thing i felt better. I ran it for another year and all was good.

I know folks will obviously say that a certified real mechanic is best, yaddy yaddy, but $200-$300 is steep if there really is no big deal with topping it up a few ounces. What do you folks think? Its unclear whether these cans have oil as well as refridgerant, i'd like to keep things in balance. Should it also have PAG oil? or are we just topping refridgerant here and thats ok? Thoughts?

 

[slacktide_bitog]

most cars new enough to have 1234yf should still be under warranty, so it shouldn't cost you anything

 

[skyactiv]

Doing what you propose is Dumb. You will add a small amount of air that will put moisture in the system. You don't want air nor moisture in the system. You can think that tiny bit is nothing which is dumb thinking. Some outboard 2-strokes run on a 100:1 mix which is also a tiny bit.

 

[RooflessVW]

Adding refrigerant blindly is not a smart move.

The best move, IMO, would be to draw the 1234yf out completely and replace it with R-134a. You'll get better performance with a smaller charge.

 

[bdcardinal]

No, you want to completely evacuate and recharge to a known proper amount. You can't do that with the A/C Pro garbage.

 

[JTK]

Just to add to the above, another potential issue to blindly adding refrigerant is, every time you use the service ports, you run the risk of having one or both not seal off. Especially if the vehicle has some age/mileage on it.

The more I read and poke around, it seems like a periodic evac, leak check, recharge and new service valve install can pay for itself for the long run of the system. I don't know what the cost is for that kind of service though.

 

[Astro14]

Adding something, anything, but particularly refrigerant, without first determining how much needs to be added, is a sure-fire way to end up with the wrong quantity. Most likely overfilled and most likely with contamination added. Not a good idea.

 

[atikovi]

most cars new enough to have 1234yf should still be under warranty, so it shouldn't cost you anything

Not really, from a web search,

Here is a list of 2018 Manufacturers and Models using HFO-1234yf:

• Acura – 0.00% (none currently)
• Audi – 22.20% (A4, Q5)
• BMW – 100.00% (all new models)
• Buick – 50.00% (LaCrosse)
• Chevrolet – 64.70% (Bolt EV, Camaro RS, Colorado LT Diesel, Malibu, Silverado 1500, Spark, Spark EV, Suburban, Tahoe)
• Fiat Crysler Automobiles – 87.50% ( Chrysler 200C, 200S, 300, 300C, Pacifica; all Fiat models; Dodge Challenger, Charger, Dart, Durango, Journey; Ram 1500; Jeep Cherokee, Compass, Grand Cherokee, Renegade, Wrangler)
• Ford – 42.89% (F-150, Focus, Fusion, Fusion Energi, Escape, Fiesta
• Genesis – 66.66% (Hyundai Genesis)
• GMC – 83.33% (All Cadillacs; GMC Acadia, Canyon SLT, Sierra 1500, Yukon XL & Denali)
• Honda – 77.77% (Pilot, Civic, CR-V, Fit EV, Ridgeline)
• Hyundai – 25.00% (Santa Fe)
• Infinity – 0.00% (none currently)
• JLR – 100.00% (all Jaguar and Land Rover models since 2016)
• Kia – 70.00% (Cadenza, Optima, Sportage, Rio)
• Lexus – 11.11% (LS, RCF)
• Lincoln – 40.00% (MKZ)
• Mazda – 0.00% (none currently)
• Mini – 100.00% (all new models)
• Mitsubishi – 50.00% (Mirage)
• Nissan – 0.00% (none currently)
• Ram – 50.00% (2019 Ram 1500,
• Subaru – 28.57% (Legacy, Outback)
• Toyota – 28.57% (Tacoma, Yaris HSD, Prius Plus, GT86)
• Volvo – 0.00% (none currently)
• Volkswagon – 71.42% (Atlas, Beetle, Golf, Passat, Tiguan)

So roughly half the new cars from 2018 use the new stuff and most of them are out of warranty by now.

 

[92saturnsl2]

I've had enough cars whose A/C was working great after 10-15+ years on unmolested factory A/C components to tell me that if it ain't broke don't fix it.

I've also had a couple that required components replaced, like an A/C condenser or evaporator. Evacuate (if not already), replace component, vacuum & test for leaks, then recharge. That process (for whatever component failed) has always yielded an A/C system that worked fine for many years after the repair.

I've never had a compressor fail on any vehicle I've owned, there are fail-safes in the system to protect it from a low charge level.

Indeed a compressor failure will likely be a bigger ordeal with possible system flush or replacing other components involved, but I don't think some DIY/hack "maintenance" would somehow prevent a compressor failure.

 

[Chris142]

The charge amount on a 1234 system is very critical. The systems don't hold much at all and the chance that you will put the correct amount in is very low.

 

[Rygrego]

I know the tree huggers won't like this but 134A will work in a 1234YF system you just need to purchase 134A to 1234YF adapters to connect your 134A Gauges to a 1234YF system. They are cheap and available for the time being.

 

[demarpaint]

They weigh refrigerant charges for a reason. Topping up based on pressures is a common practice, but a shot in the dark imo. Unless the system is not working properly I would leave it alone.

 

[dihi22]

I've had enough cars whose A/C was working great after 10-15+ years on unmolested factory A/C components to tell me that if it ain't broke don't fix it.

I've also had a couple that required components replaced, like an A/C condenser or evaporator. Evacuate (if not already), replace component, vacuum & test for leaks, then recharge. That process (for whatever component failed) has always yielded an A/C system that worked fine for many years after the repair.

I've never had a compressor fail on any vehicle I've owned, there are fail-safes in the system to protect it from a low charge level.

Indeed a compressor failure will likely be a bigger ordeal with possible system flush or replacing other components involved, but I don't think some DIY/hack "maintenance" would somehow prevent a compressor failure.

Wow, thanks thats a great answer. I'm going to put down this AC Pro can the guy in the alley way sold me and carefully step back away from my car...

I'll just monitor performance of the ac with a thermometer and if she ain't as cool as she used to find a good independent AC guy to vaccuum, test for leaks, etc. then just let them refill.

Unless i get into buying gauges and vacuums and studying more i shouldn't touch this stuff.

 

[kschachn]

Wow, thanks thats a great answer. I'm going to put down this AC Pro can the guy in the alley way sold me and carefully step back away from my car...

That may be the best course of action, all things considered in this thread.

 

[demarpaint]

Wow, thanks thats a great answer. I'm going to put down this AC Pro can the guy in the alley way sold me and carefully step back away from my car...

I'll just monitor performance of the ac with a thermometer and if she ain't as cool as she used to find a good independent AC guy to vaccuum, test for leaks, etc. then just let them refill.

Unless i get into buying gauges and vacuums and studying more i shouldn't touch this stuff.

Smart move!

 

[Astro14]

Wow, thanks thats a great answer. I'm going to put down this AC Pro can the guy in the alley way sold me and carefully step back away from my car...

I'll just monitor performance of the ac with a thermometer and if she ain't as cool as she used to find a good independent AC guy to vaccuum, test for leaks, etc. then just let them refill.

Unless i get into buying gauges and vacuums and studying more i shouldn't touch this stuff.

Honestly, even with gauges, and refrigerant, drawing it down and refilling by weight is best. I’ve got an EPA 609 license, and a nice set of gauges, vacuum pump, etc, but it’s not as simple as it seems, even with R-134. I’m no expert, I know just enough to know that I don’t know enough about AC systems.

When someone who does this for a living, like @Chris142 , says “don’t do it” then you shouldn’t do it.

 

[Chris142]

Honestly, even with gauges, and refrigerant, drawing it down and refilling by weight is best. I’ve got an EPA 609 license, and a nice set of gauges, vacuum pump, etc, but it’s not as simple as it seems, even with R-134. I’m no expert, I know just enough to know that I don’t know enough about AC systems.

When someone who does this for a living, like @Chris142 , says “don’t do it” then you shouldn’t do it.

Thanks! I'm with you on going by pressure. Does not always work. Starting from empty with a vacuum is best.

 

[zzyzzx]

I would check for dirt and bent fins in the condenser before I would blindly add refrigerant.

 

[Schmoe]

I tried the diy approach with R134a, that cost me. Overfilled it even after following that guage that comes with the bottle. Never again. Not worth it.

 

[RooflessVW]

I tried the diy approach with R134a, that cost me. Overfilled it even after following that guage that comes with the bottle. Never again. Not worth it.

The minimum tools required to self-service R-134a (IMO) are: gauges, a vacuum pump, a scale, and a willingness to vent refrigerant to atmosphere.

You MUST draw a hard vacuum, you MUST verify that there are no leaks, you MUST service the system by weight, and you MUST verify pressures.