A/C recharge issue/R134A shelf life?

[HawkeyeScott]

Weekend tasks will include a recharge of a 1998 Rav4 air conditioning system that is only blowing about 55 degree air. The system seems to be performing well, though the high/low pressures suggest it needs topped off.

First attempt with approximately 10 year old can of refrigerant resulted in no visible refrigerant being pulled into the manifold gauge via the yellow hose. When I bled the line with the valve, nothing but what felt like air came out. In other words, the refrigerant wasn't visible in the little window or at the Schrader valve. Yet, the can started to get cool.

Question is, has the refrigerant/can sat too long? The internet says the shelf life of 134-A should be very long. I've always been able to see the refrigerant briefly "spray" when burping the gauge valve, signaling the line is full and ready to charge the system.

FWIW, the manifold gauge set is a brand new borrowed set from AutoZone. It seems to be in working order.

Thanks for any thoughts. Have a great weekend, everybody.

 

[Cujet]

134 is 100% stable. No degradation over time and has an indefinite shelf life.

Some thoughts. Underperforming systems are generally low on charge, but there are times where moisture and or air was introduced and can cause issues. Also the evaporator can require cleaning. It becomes obvious when the condenser requires cleaning but worth mentioning too.

Turn the can upside down in brief spurts.

 

[Eddie Hudson]

I added a 10+ year old can (non self sealing) to my system yesterday with no problems. Did you make sure all the valves are open?

 

[mk378]

New cans have a reclosable valve. Old cans are pierced once. The top of a reclosable can looks like a spray can with the nozzle pulled out. The top of a nonreclosable can is flat metal. The can tappers are different though they look much the same. You may be trying to use the new type tapper on an old can.

A full can is heavy and feels like liquid when you shake it.

 

[Nukeman7]

First attempt with approximately 10 year old can of refrigerant resulted in no visible refrigerant being pulled into the manifold gauge via the yellow hose. When I bled the line with the valve, nothing but what felt like air came out. In other words, the refrigerant wasn't visible in the little window or at the Schrader valve. Yet, the can started to get cool.

Question is, has the refrigerant/can sat too long? The internet says the shelf life of 134-A should be very long. I've always been able to see the refrigerant briefly "spray" when burping the gauge valve, signaling the line is full and ready to charge the system.

If you want to see the refrigerant appear in the viewing window and "spray" out of the hose couplings, you should turn the can upside down during the purge sequence to discharge liquid R-134a. However, it is already purging correctly (in the gaseous state) if you can hear the hissing sound and the outside of the can gets cool.

 

[mk378]

When charging as gas with the compressor running, you should see the low side gauge jump up to about 90 psi and the high side slowly increase. The sight window in the manifold is a gimmick that really has little use. More expensive professional manifolds don't have one.

 

[TCL]

If it's a small store bought can, make sure it is getting punctured by the tip.

 

[Bailey28]

As a shade tree mechanic I think the importance of bleeding air from the a/c gauge lines after connecting them is underemphasized. I think most DIY videos show the connections and charging but leave out a thorough air purge.

Any air in the system will lower the cooling output noticeably. When I first started using gauges I was guilty of introducing air into the system and eventually figured it out.

 

[Snagglefoot]

I’m guilty of hooking up the red high pressure line, seeing if it still has a charge in the spring, say at 68 F. If it has at least 50 psi, I immediately use the short blue loading hose from my R12A kit, screw on a can, purge the short line, then hook up and load in a 6 oz can. I’m using R12A, a propane/butane mixture legal in Canada and the EU. I switched to it several years ago. The system is 16 years old and after I replaced a few items I put the system on vacuum and loaded in R-12A.

 

[D60]

I agree the can taps are problematic -- or at least easily confused. Order several on Amazon. They're cheap and seem almost like consumables -- but maybe that's because I'm using cheap ones!

I had a bad experience with Mastercool taps (can't recall the exact issue now) and then decided to just use basic import stuff. They're also easy to lose so I like to have backups

 

[Chris142]

Refrigerant never goes bad. Many people here do not know this.

 

[mk378]

The only way a can would go bad is by leaking out.

 

[HawkeyeScott]

If you want to see the refrigerant appear in the viewing window and "spray" out of the hose couplings, you should turn the can upside down during the purge sequence to discharge liquid R-134a. However, it is already purging correctly (in the gaseous state) if you can hear the hissing sound and the outside of the can gets cool.

Thanks.

So, this is all happening but for seeing the "spray." Which is what is confusing me. Hissing sound, cool can, but no spray when attempting to bleed the yellow hose.

You're thinking that the can is being evacuated and that I should open the low side to start charging, even if there is no visible spray?

That makes sense...but I keep wondering where the spray is.

 

[Nukeman7]

Thanks.

So, this is all happening but for seeing the "spray." Which is what is confusing me. Hissing sound, cool can, but no spray when attempting to bleed the yellow hose.

You're thinking that the can is being evacuated and that I should open the low side to start charging, even if there is no visible spray?

Yes, you can charge if you hear hissing from the end of the red and blue hose ends. Be sure to purge the hoses BEFORE you connect it to the car's A/C system...otherwise the hissing noise may be refrigerant leaking out from the car.

That makes sense...but I keep wondering where the spray is.

The visible spray is the R-134a escaping as a liquid aerosol. If it is discharged as a gas, you won't see visible spray.

 

[HawkeyeScott]

Yes, you can charge if you hear hissing from the end of the red and blue hose ends. Be sure to purge the hoses BEFORE you connect it to the car's A/C system...otherwise the hissing noise may be refrigerant leaking out from the car.

The visible spray is the R-134a escaping as a liquid aerosol. If it is discharged as a gas, you won't see visible spray.

Great - thanks for sharing your expertise. Very much appreciated.