Do not top-off AC refrigerant????????????

[Gene in NC]

Bently pp 640-8 hss the following. What the heck are they talking about? What is the risk in topping -off? Sounds like something from the AC technicians union.

CAUTION --
Do not top-off AC refrigerant in a partially charged system. Discharge system, evacuate and then recharge the system.

[winfred]

if you know what you are doing you can top it off but taking a proper measurement is best. did ya blow sumthin up?

[Gene in NC]

No need to top e34 but my e28 needs a little pop. Never heard of not topping up. Suspect some validity in caution and a set of guages to measure pressure addition may be required. Maybe I was just lucky in the past.

[Blitzkrieg Bob]

I have seen a few ruptured A/Cs from too many of those DIY can refills.

Yup...I think just one more can otta get her nice n cold....bam!...ssssssssssss

[winfred]

if you are topping up with r12 you can watch for the sight glass to clear on a low rev but i find they are not that reliable with r134, espicially on a converted car

[dacoyote]

It's very important that if you are going to mess with it that you the very least you have the guage for the Low Pressure side. You can over change the system and ruin it really farking fast.

[CheapCheap1]

it recommends to fill up R134a only 80% of the volume (approx. 40-45psi on the "low" pressure side).

Too much refrigilant in the system will NOT make the AC cooler. But it could blow up the system.

[winfred]

the pressures change too much from system to system to depend on a certain psi and ambiant temp plays a good role too, besides on some cars after you get the first can in the low side doesn't change more then a few psi, a e34 takes 4.2 pounds of r12 and 3.5 pounds of r134, high side is what you want to watch for problems aux fan usually kicks into high around 300 psi, 375 aint the end of the world but aint good ether (you usually only find pressures like that on older systems that have been converted, i've seen over 400) the main problem with over charging is too much liquid on the low side hammers the compressor, it'd much rather suck vapor then liquid


it recommends to fill up R134a only 80% of the volume (approx. 40-45psi on the "low" pressure side).

Too much refrigilant in the system will NOT make the AC cooler. But it could blow up the system.

[Gene in NC]

OK, I got the message. Have a bud who has the gear to do it right- pull it out, evac and reload.

[632 Regal]

if he has the right stuff you dont really need to evac.

[Bellicose Right Winger]

I think it's a fair warning. For example how do you top off a system that doesn't have a sight glass like E36's? How about the guy who sees a bubble in his sight glass every 15 seconds, which indicates a very slight undercharge, and decides to add a 14 oz can?

Paul Shovestul




Bently pp 640-8 hss the following. What the heck are they talking about? What is the risk in topping -off? Sounds like something from the AC technicians union.

CAUTION --
Do not top-off AC refrigerant in a partially charged system. Discharge system, evacuate and then recharge the system.