Automotive Air Conditioning Information Forum (Archives)

wdcruz523 on Tue August 20, 2013 5:17 PM

Year: 2001
Make: Toyota
Model: Celica GT
Engine Size: 1.8L
Refrigerant Type: R134a
Ambient Temp: 90

I read that 2-3oz of refrigerant can remain in the manifold gauge and hoses after use. So if I charge a system with the recommended amount of 16 oz of 134a, then remove the gauges, I guess what's actually in the system is 13-14oz total. Also, each time the gauges are used to check pressures, you lose another 2-3oz's?

Edited: Tue August 20, 2013 at 10:13 PM by wdcruz523

webbch on Tue August 20, 2013 5:57 PM

If your hoses are empty when you start, then they must fill up with refrigerant before any starts going into the vehicle. That's where you get the 2-3 oz "loss". Unless you intentionally purge them, the hoses generally have valves that prevent the refrigerant from emptying out. Thus, on subsequent uses, that "loss" would be substantially less.

Now if you're changing between R-12 and R-134a on the same gauge set, you need to purge the hoses to avoid cross contamination, but that's a different issue.



Edited: Tue August 20, 2013 at 5:58 PM by webbch

wptski on Tue August 20, 2013 6:18 PM

I used this as a guide Charging with Cans(if that's what you used), a small digital scale weighing before, during and after.

wdcruz523 on Tue August 20, 2013 10:06 PM

Thanks. One more question. Since I don't have a scale and refrigerant tank, I need to go by pressures and ambient temp. I'm not sure what information I should rely on.

First I have the Toyota FSM -





MPa conversions -
Low = 21.7 to 36.2 PSI
High = 198.7 to 227.7 PSI

-----

Then there's the R134a chart -



What conditions should the system be running when using this chart? Idle or 1500+ RPM? Doors/windows closed or open?

I don't understand why at 90F the chart says I should have at least 250 PSI on the high side, but on the FSM, max high side is just 227.7 @ 86F to 95F.

Edited: Tue August 20, 2013 at 10:08 PM by wdcruz523

Leggie on Wed August 21, 2013 12:03 AM

Don't trap liquid refrigerant in line and loss is negligible.

2-3oz seems plausible if the entire volume of path is filled with liquid refrigerant. If you charged as liquid, do the last bit of charging as vapor to push all the liquid into the system.



Edited: Wed August 21, 2013 at 12:07 AM by Leggie