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Charging Problem

fslec on Tue June 08, 2010 8:36 AM User is offline

Year: 1984
Make: Ford
Model: Mustang
Engine Size: 2.3
Refrigerant Type: 134a
Ambient Temp: 70
Pressure Low: 90
Pressure High: ?
Country of Origin: United States

Started with system drawn down into a vacume of -30psi
With guages hooked up - connected 1st can of 134a and it took almost 15 min to get the hole can into the system.
Compressor started to short cycle - 1/2 sec on 5 sec off
Tried to charge with second can and low side pressure just stayed aprox 90 psi and it wouldnt take the charge.
Jumped low pressure switch trying to create some vacume in the suction line and the pressure just sits at 90 psi.
After about 10 min the high side line going to the evaperator started to frost at the evaperator - low side remained at 90 psi.
Pressure after about 1 hour and system equalized - low side still at 60psi

Bad compressor or system blocked??
The system had been open for awhile but all line ends were capped.

I'm suspecting compressor because it doesn't seem to draw the suction line down at all while running.

mk378 on Tue June 08, 2010 12:07 PM User is offline

You were just measuring the pressure in the can, it wasn't coupled to the car properly. Use a decent gauge manifold with two gauges, it's important to watch the high side pressure while charging. Whenever the compressor is cycling and you have sweating or frost on the lines, the real low side pressure is much less than 90 psi.

Is it properly converted for R-134a? Did you check condition of orifice tube, and install a new accumulator drier? After sitting open the old one will be saturated with water and useless for it's purpose.

For initial charging hold the can upside down with the engine off, it will go in much faster.

Edited: Tue June 08, 2010 at 12:10 PM by mk378

jgcox6 on Wed June 09, 2010 2:46 PM User is offline

i have a question relating to the advice given about the "initial" charging of a system when work has been done.....are you saying that you can turn the 134 can upside down and charge the system that way...(with the engine off)?? Does that not flood the compressor? I have always wondered about that..

98audiA4 on Thu June 10, 2010 10:10 AM User is offline

not a seasoned vet here but with the engine off the compressor isnt pumping anything, once the liquid goes in it'll turn to gas as it expands into the system.

bohica2xo on Thu June 10, 2010 10:47 AM User is offline

You can safely charge liquid into an evacuated system with the engine stopped. BUT, you should be careful WHERE you charge the liquid.

The liquid should be charged into the HIGH side of the system. On a few vehicles, there is a port located ON the accumulator. In this case it is OK to dump liquid into the accumulator on the low side.

Avoid introducing liquid into a low side port near the compressor. Liquid refrigerant is a great solvent, and can wash away all of the lubricant as it expands through the stopped compressor.

Just best to add liquid to an evacuated system through the high side port - with the engine off.

Remember to close the high side valve on your manifold BEFORE starting the engine. The high side valve should remain closed while the system is pressurized.


"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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