A/C Charging: In Progress...

A/C Charging: In Progress...

'02 Impala 3.4L 150k miles

It's 94 degrees here with 45% humidity.

Static Pressures before running engine first time: 98 psi (L), 90 psi (H). After running engine first time: 110, 105

Running Pressure (prior to charging) @ idle: 31..34 (L), 145..195 (H). Vent temp off the charts HOT.

AFTER charging 1 full (10 oz?) can: 35..51 (L), 195..240 (H). Vent temp down to 60F.

QUESTION IS:
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Documentation I've read says R134a HIGH side should top out at about 2.2 to 2.5 times ambient. At 94F, that's a range of 206F to 235F. I'm already maxing out at 240F on the high side after one can. But my vent temp is only 60F.

Are the 2.2 and 2.5 numbers correct? Can I actually (and safely) go higher on the HIGH side ... say 250-260 ... or whatever it takes to get the vent temp down to, say, 50F?? 60F is not that cold for a vent temp. I don't want to overcharge it, of course ... and I don't want any explosions either ...

I did this last April when ambient temps were at least 10 degrees lower and I was able to achieve a vent temp of under 50 degrees! I know I have a leak somewhere and I hope to find it this time around with residual dye from last year (this year's stuff doesn't contain any dye).

A/C Charging: In Progress...

'02 Impala 3.4L 150k miles

It's 94 degrees here with 45% humidity.

Static Pressures before running engine first time: 98 psi (L), 90 psi (H). After running engine first time: 110, 105

Running Pressure (prior to charging) @ idle: 31..34 (L), 145..195 (H). Vent temp off the charts HOT.

AFTER charging 1 full (10 oz?) can: 35..51 (L), 195..240 (H). Vent temp down to 60F.

QUESTION IS:
----------
Documentation I've read says R134a HIGH side should top out at about 2.2 to 2.5 times ambient. At 94F, that's a range of 206F to 235F. I'm already maxing out at 240F on the high side after one can. But my vent temp is only 60F.

Are the 2.2 and 2.5 numbers correct? Can I actually (and safely) go higher on the HIGH side ... say 250-260 ... or whatever it takes to get the vent temp down to, say, 50F?? 60F is not that cold for a vent temp. I don't want to overcharge it, of course ... and I don't want any explosions either ...

I did this last April when ambient temps were at least 10 degrees lower and I was able to achieve a vent temp of under 50 degrees! I know I have a leak somewhere and I hope to find it this time around with residual dye from last year (this year's stuff doesn't contain any dye).

install the correct amount of refrigerent. with temp of air at the vent this is variable ..the more the humidity is ,,, the higher the vent temp. these evap units [r134] do not perform well with high dewpoints 60 deg plus....with the older vehicles designed with R12 the evap coil spacing was greater and therefore this was not much a factor...

I would expect at 95 deg f the high side on most vehicles will be 250 psi plus high side..the evap can be dirty also . this will cause poor high vent temps as well as excessive water on those coils..all this interferes with the hot air being cooled...................

I couldn't wait and found a MasterCool table online that said, for R134a and 95F, I could have a LOW side of 50-55 psi and a HIGH side of 275-300 psi, so I charged a 2nd can.

I ended up at a LOW side high of 42 psi and a HIGH side high of 232 (with vent temp of 49-50F). Interesting that the vent temp dropped some 10F, but the gauges didn't change much at all ! My final STATIC pressure ended up at 80 psi on both LOW and HIGH side gauges (if that means anything).

I just checked my notes from last year ... I had achieved 42-43F vent temps with the Impala. Almost seems like it might be able to take a little more, but I'm going to drive it first and see how it performs at road speed.

Thanks for now...

I couldn't wait and found a MasterCool table online that said, for R134a and 95F, I could have a LOW side of 50-55 psi and a HIGH side of 275-300 psi, so I charged a 2nd can.

I ended up at a LOW side high of 42 psi and a HIGH side high of 232 (with vent temp of 49-50F). Interesting that the vent temp dropped some 10F, but the gauges didn't change much at all ! My final STATIC pressure ended up at 80 psi on both LOW and HIGH side gauges (if that means anything).

I just checked my notes from last year ... I had achieved 42-43F vent temps with the Impala. Almost seems like it might be able to take a little more, but I'm going to drive it first and see how it performs at road speed.

Thanks for now...


the pressures look good. the temps are normal. too much refrigerent is destructive ..best error on less than too much ..