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pulling vacuum with partial charge?

lizardflats on Wed November 17, 2010 2:24 PM User is offline

Year: 1996
Make: Ford
Model: Explorer
Engine Size: 5.0
Refrigerant Type: R-134a
Country of Origin: United States

I had to have my A/C evacuated at a shop to remove the evaporator so that I could replace the heater core in our Explorer. The A/C was working fine before the heater repair. I didn't lose any oil in the process and the ports were covered when the evaporator was out (about a week). I've got everything back together now.

I started to do a recharge last night, but realized after putting in about 6-8 oz of R-134a that
1. I need to jumper the low side pressure switch to get the compressor to come on.
2. I really should pull a vacuum to dry out the system.

I can rent a vacuum and manifold guage kit at the local Autozone. My question is whether I can pull a vacuum with the partial charge in the system?

Then, once I have the system pumped down and dried out, I can add the rest of the specified charge (1 lb 14 oz total).


TRB on Wed November 17, 2010 2:53 PM User is offlineView users profile

You must reclaim any refrigerant in the system before pulling a vacuum.


When considering your next auto A/C purchase, please consider the site that supports you:

lizardflats on Wed November 17, 2010 4:08 PM User is offline

I thought so.


Dougflas on Wed November 17, 2010 6:44 PM User is offline

you should change the drier/accumulator also

bohica2xo on Thu November 18, 2010 3:51 PM User is offline

You should really put the jumper wire back where you got it.

Or, you can jumper the low pressure switch. Make sure you get that compressor spinning right away, in vacuum. Rev the engine up to about 1800 rpm for good measure. Now, fumble around getting the charging lines on, & the can tapped. This gives the compressor a chance to get good & warm. Now that the compressor is hot, with no refrigerant mass flowing through it for cooling & no oil returning from the refrigerant loop you can begin charging. Charge as a gas through the low side, and take your time. Refrigerant gasses are great degreasers, so this will help wash away any lubrication left in the compressor. By now you should be able to warm dinner on that compressor.

Eventually, you will either get it charged, or the seized compressor will snap the drive belt. If you get the charge in, you can wonder why the A/C never works as good as it did before the re-charge. With some scuffing damage & huge clearances from running without oil or cooling (thanks to the jumper wire) your compressor just can't match the old performance levels.

Jumper wires sell compressors.

"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

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