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how long does r134 take to enter system

vdubnut on Thu August 30, 2007 1:25 PM User is offline

Year: 1991
Make: chev
Model: suburban
Engine Size: 5.7
Refrigerant Type: r134
Ambient Temp: 85
Country of Origin: United States

I am wondering about filling my system after replacing my compressor, system flushing, filling with oil, evac, then charging....

first, with no charge in the system the compressor wont turn on because of low pressure switch....should i jumper it or fill system with freon up to the point that the switch engages? long should i expect it to take to put in a 12 oz can of freon in?

I started out just putting freon in without the compressor on, then it seemed that the freon stopped going in, so i jumpered the compressor, then it seemed to be pulling it in but it was taking 10+ minutes and the compressor was getting hot. so i stopped everything.....hopefully not too late...

any advice?

Chick on Thu August 30, 2007 1:43 PM User is offlineView users profile

Did you pull a deep vacuum and charge into the vacuum as a liquid??
Vac/charge procedure Has to be done this way..Hope this helps..

Email: Chick


Freedoms just another word for nothing left to lose

vdubnut on Thu August 30, 2007 2:10 PM User is offline

that hyperlink mentions..."should be charged as a gas but sometimes as a liquid" so do i charge a can or two as a liquid, ie can upside down? then the rest as a gas....

"be careful not to slug the compressor with liquid freon"

mk378 on Thu August 30, 2007 2:56 PM User is offline

When starting from vacuum, charge as liquid with the engine off. Open both valves on the manifold. Hold the can upside down and shake it. Put in as much as you can that way then close the manifold valves. If you want, turn the compressor by hand first to be sure it is not full of liquid. Then double check that manifold valves are closed, start up the engine, turn A/C on, and complete the charge into the low side. Jumping the switch is not recommended. Let the compressor cycle and it will still be able to pull more in.

vdubnut on Thu August 30, 2007 4:05 PM User is offline

thanks....hopefully that will work.

my vacuum pump is insufficient i believe so im going to a friends shop in the morning to have him bring it down for me....then i will fill as you recommend.

one more question if you dont mind...

does the oil and 134 mix in order to circulate? so if it was pooled in the various places(condensor, compressor) etc, does the 134 pick it up on its way by?

thanks for your help....i wish i found you guys earlier in this process!


Chick on Thu August 30, 2007 5:18 PM User is offlineView users profile

Yes, if you didn't flush the system the only oil removed is in the part you took off. On your car, the low side port in on the accumulator so it's safe to charge as a liquid. it will boil off before hitting the compressor. Be sure to add back the proper amount and type of oil for the parts replaced.. Hope this helps.

Email: Chick


Freedoms just another word for nothing left to lose

Edited: Thu August 30, 2007 at 7:38 PM by Chick

Ralliart16 on Thu August 30, 2007 7:26 PM User is offline

I've charged all my systems with 12oz cans, and this is what i do.

First do all your standard procedures, and after you have let it hold vacuum to boil off moisture, hook the can up and charge into the vacuum. The vacuum will suck a lot of refrigerant into the system, enough to make the compressor run for sure. I do this with the car off. Then once I feel it stop sucking the refrigerant in, I turn on the car and a/c and run it on maximum with the car between 1500-2000 rpms.

It takes quite a few minutes for the system to suck the refrigerant in. What I do is set the can inside the engine bay (NOT near the belts or anything dangerous), so that it keeps the can warm, since the can will get really cold from discharging the refrigerant. Keeping it warm will increase the pressure in the can and make it enter the system faster. Do NOT take this to the extreme and heat the can with a torch or something (i've heard of people doing this...)

Edited: Thu August 30, 2007 at 7:26 PM by Ralliart16

Dougflas on Thu August 30, 2007 7:45 PM User is offline

Shaking the can of refrigerant does nothing. All you can tell from shaking is if there is refrigerant left in the can. You can leave the can right side up, place it in a pot of hot water. This will raise the temp of the gas thus raising the pressure.

vdubnut on Fri August 31, 2007 12:12 AM User is offline

thanks all for your help....

hopefully i will be enjoying cold air tomorrow on my trip!

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