a/c almost done....evac/recharge issue

with a long rainfree weekend i was finally able to attack the a/c evaporator core and was successful in replacing it. the problem comes from the evac/recharge step -
i purchased a set of manifold gauges from auto zone, and they let me borrow a pump. cool beans. i hook it all up as directed and turn the pump on, the directions say to pump till you hit 29 bars or so, then leave it on for one hour. it went to 29 bars in about one minute, with a 2.0 cfm pump i dunno, sounds ok to me. after an hour i stop the pump and let it sit for 1/2 hour - no increase in pressure so all should be cool, right?
i shut down both sides, hook up the yellow hose that was on the pump to a can of 134a, then start the engine and turn on the a/c and open the blue valve into the low pressure side - -nothing. guage doesnt move. i checked and triple checked that the valves were open thru to the low side connector. i slightly disconnected the yellow hose clamp onto the 134a can and confirmed the can was full and had been punctured. unhooked the blue quick-connect and opend the valve so the guage did read zero (up from negative). hooked all back up and tried again - nothing.
disconnected the whole contraption and used the little el-cheapo refill hose and got the system charged correctly, and it works.
anyone have this problem? if the guages will not allow 134a to enter the system, then when i did the evac was i just evacuating the hoses and not my a/c system? is that why it hit 29 bar so fast, or is that normal?
i am thinking i need to vac out all the coolant in there now and try this again
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evaporator
borrow a

one
dunno,
hour -

can
into
triple
slightly
was
the
and
hose
my a/c

again
It won't fill unless there is suction, which requires the compressor to be jumped directly from the battery when the system is completely empty.
Doc

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???? then why does the little recharge hose work? there seems to be enough pressure in the can to do it with that set up, and the compressor cuts on when there is sufficient pressure in the system.
does the manifold gauge set havd some sort of baffles in there or something?
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there is a sensor on the compressor to tell it when the vaccum is too low, so it will not run to burn up when there is no freon in the ac system, my suggestion would be unplug the sensor from the compressor and stick a jumper from one side of the connector to the other. Going directly to the battery will also work.

be
enough
when
something?
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i understand, and i greatly appreciate your insight and patience, but what i dont understand is why the cheapy little hose is able to charge the system using only 134a can pressure, whereas you say the expensive professional manifold set cannot?
i got 3.5 cans in the system in about 45 minutes and its cold. my question is - if the professional manifold sytem couldnt charge it, should i worry if it properly evacuated it? should my system go from 0 to -1 bar (-29 psi) in a minute or so with a 2 cfm pump???
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jumper
battery
i
question is

it
a
Sounds like yer' hose is plugged bud. It should creep down slowly over an hour or so, not instantly.
Doc
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ok - went back to AZ - - the FRIGGIN hose does not come with an actuating pin!!!!!!!!!!!!!!!!!!!!!!!!!!
as much help as my local AZ guys have been, AZ still fails in not equipping their stores with a two dollar part that i need to complete an $800 job....(parts only)
THANKS doc, and others who have chimed in over the past month.
dont you feel sorry for the minions who say "what?" when you mention "usenet newsgroups" ?
usenet rocks, and its people like all of you and doc that do it. i use it for dog help, surfing fun, home repair, gardening, etc etc the works.....
thanks again
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snipped-for-privacy@aol.com (Surfgeotwo) wrote:

So it looks like you're going to have to recover, evac and recharge all over again.

That's loaner tools for ya, the last guy probably lost the valve depressor.

Or put the other way, isn't it great when someone knows what it is?

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