Only 20 psi left in low psi side of a/c...how much to charge?

["Turbo-T"]

My a/c leaks slowly but surely. Today with the engine off I determined there's still 20 psi left in the system on the low pressure side.

I'm going to charge it up to get me by until I can fix the leak this winter. But I'm not sure how much refrigerant (it's been converted to R134a) I should put in or even how much oil to put in...???

Or would I just be better off to suck it all down/evaculate the system and just start over fresh?

 

[Roger]

A/C operating low side should have 30 - 60+# pressure which varies with ambient temperature - lower pressure at lower ambient temps & higher pressure at higher ambient temps.

Static (a/c off), low side should have somewhere around 120#.

 

["Turbo-T"]

Thanks Roger.

Was thinking the 20 psi that was in the low side w/o the compressor not running was low but ok...didn't realize I think I read somewhere the pressure equalizes across the whole system when not running. Also there was less than 25 PSI on the high side with the a/c off. So this was way low.

Anyways I decided to just evacuate the whole system and start over fresh. Just got done unplugging the vacuum pump after running for a whole hour. So far the vacuum is still holding at 30 hg.

At least I was able to use the existing 20 psi in the low side to adjust the pressure switch on the accumulator-drier per AC 134a Retrofit. Took 2.5 turns from it's original position to get it to work.

 

["Turbo-T"]

Added 3 12 oz cans and a can of Pag 150 oil, it's 80 degrees and the gauges read 35 on the low and 190 on the high. Temp output seems to only be 60 degrees if that. Shouldn't it be colder? Should I add another 12 oz can of R134a?

 

[pacecarta]

do you have a large fan blowing across the condenser core ?
is the idle at 1500?
is the blower motor on hi?
are you mixing in heated air (is the heater door closed -look for a broken linkage rod behind the glove box) ?
is the vac lines to the hvac in good working order (no blown check valves no split leaking hoses) ?

i manage to see 34 degree at dash at even warmer ambient temps

charge should be 75-85% of R12
so one 12oz can of r134 equal to what would have been one 16oz of r12 plus a little more depending

empty the system needs 3.25lb r12 so you need about 3 1/2 -3 3/4 12oz cans of r134 , as you add check that you're charge on low is at 35-38 psi compressor running , adding the fan helps to get the last of the charge to full
start adding the 4th can and watch the low side that it doesnt go too high and watch the temps , if they no longer drop as you add refrigerant you're done .
oh and btw if you're using the cheap retro kits ive checked every kit gauge i ever had and have yet to find one that reads correctly , even the ones on the quick charge cans were way off

 

[Roger]

Have you located & repaired the leak?

 

["Turbo-T"]

do you have a large fan blowing across the condenser core ?
is the idle at 1500?
is the blower motor on hi?
are you mixing in heated air (is the heater door closed -look for a broken linkage rod behind the glove box) ?
is the vac lines to the hvac in good working order (no blown check valves no split leaking hoses) ?

oh and btw if you're using the cheap retro kits ive checked every kit gauge i ever had and have yet to find one that reads correctly , even the ones on the quick charge cans were way off

Idle was at 775, no fan other than the stocker drawing air, blower was on hi but then I bumped it down since less air across evaporator = colder air, no heated air is mixing that I can tell, not sure on vac lines.

But I did take it for a spin and the temps dropped some, so i thought it was due to not enough air across condensor, but then again our factory R134a Honda seems to cool quicker than the Buick. I know it's designed for R12 but have also heard it's due to R134a not being as efficient as R12.

Oh and no I was using an R134a manifold kit, the one with the red, blue and yellow hoses.

Have you located & repaired the leak?

Yes on location, no on leak. It's the compressor at the shaft for the pulley/clutch. Long story short due to lack of time and funds I'm not going to be able to fix it until this fall. So I'm just going to enjoy it as I can until I can fix it right.

 

[8UWITH6]

Sounds like your doing it right. I was in a hurry this year and just added 3 cans of 134a and suffered not so cold air. I dont have the time to jack with it so I had my tech at work evac and recharge it. He said I was close on the charge but there was lots of air in the system taking up space. I see 38 degrees on the highway and upper 40s lower 50s in traffic around town. I have a leak too aka A/C lines.......... you might add just a little more refrigerant and see how it responds.