Adding freon

[lutronjim]

I have always heard that you added freon until the bubbles just stopped in the sight glass which I have done in past.

I recently bought freon that had a gauge attached. Instructions said to add freon to the low pressure side then stop, let gauge stabilize, and if in green quit adding freon. Too much pressure might occur in operation if you added to try to get to the top of green.

I followed instructions. When I put the cap back on and checked the sight glass - there were still bubbles flowing.

Too me that says its still low. Which is correct?

If it makes a difference it a VA system on my LS 70ss that is several years old.

Thanks

[Steeveedee]

Is your system calibrated for R134? I never saw a can of anything other than R134 that had a gauge on it. Maybe that's new. I still have a vacuum pump and gauges, and a tank of R-12 (which is just about empty). Depending on the local conditions, you might see bubbles in an R-12 system. So, what are you running?

I guess if you had the system open and didn't evacuate before a recharge, you could have air bubbles. I'll also ask what temperature you were getting out of an AC vent. It's possible that you have a sufficient charge.

[lutronjim]

Sorry wasn't thinking. It's 134a and it hasn't been opened. This is just the 2nd time I've had to add freon.

[Davidf]

The sight glass will only indicate proper charge if using r12. With r134a, the sight glass is meaningless and must fill by pressure or weight.

[Steeveedee]

^ What he said!