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Very slow re-charge

Fishbone on Wed October 03, 2007 9:50 PM User is offline

Year: 1999
Make: Mercury
Model: Sable
Engine Size: 3.0
Refrigerant Type: R134
Ambient Temp: 75
Pressure Low: 75
Pressure High: 125

Today I finished a change-out of the major components of our Sable's AC system. Below is a rundown of what I installed:

New compressor
New drier/accumulator w/switch
New manifold hose(s) w/ switch
New condenser
New orifice
The only original remaining components are the condenser to evaporator liquid line and the evaporator itself. I blew out the original liquid line and evap. core before installing the new orifice. Somewhat clean oil was the only material that came out of these components.
As far as oil goes, I emptied out the new compressor of it's pre-charge so I would know how much was in it. I spread out about 7 oz. of oil between the compressor, the evaporator core, and the drier.
I then vacuumed out the system 3 times (diaphragm type) for about an hour each. The system held a vacuum sufficiently.
Now it came time to charge with R134a. I am using the 12 oz. cans through the yellow pick-up tube on the gauge manifold. The R134a was going in very slow. Initially, I let about 1/2 of a can flow in with the engine off. I then started the engine and jumped the low pressure switch and got the engine up to about 2K RPM in order to get the stuff to move. It took 45 min. to an hour to get the 1st can in. The 2nd was even slower. I managed to get another 1/2 can in when I gave up to the day. The low side reading (engine/compressor running) was +/- 75 PSI while the high side stayed around 125. It was 70 to 75 degrees outside. I was getting some cold air through the vents when I started the 2nd can. The compressor would not stay running without being jumped. The low press. switch is also new.
I did notice that there was some frost forming on the liquid line between the orifice and the evap. firewall fitting. I am going to let the car sit overnight to see if the pressure on both sides equalizes and give it another shot tomorrow. The car should take 3 cans of R134a since it was completely empty.
Is what I described here normal? Thanks.

iceman2555 on Wed October 03, 2007 11:39 PM User is offlineView users profile

The frost ring at the orifice tube is not uncommon on Ford units with a undercharged system....once the system is fully charged...it should go away.
Since the ambient temp is low...try warming the charging cans in warm water as you are charging the system...this will increase the pressure/temp of the refrigerant in the cans and 'force' the refrigerant into the system. Warm water is sufficient.....not boiling.....simply attach your cans in the normal manner....have a container with warm water hand...and place the can in the warm water....open the gauge....
Good rule of thumb...charge until the inlet and outlet of the evap are the same temp......best to do with the doors open......
Good luck....

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

Fishbone on Thu October 04, 2007 9:10 AM User is offline

Thanks, I'll give the warm water trick a try. I just ran out to the garage and took a static pressure reading after the car sat all night. 65 PSI on both sides.

2POINTautO on Thu October 04, 2007 10:00 AM User is offlineView users profile

Remember to crack open your manifold gauge to bleed out some system freon back out of the system to purge the air out of the hose prior to tightening the can on the yellow hose.

With temps at or below 75F, there are these issues, hot water buckets are the preferred method of charging with cans in Japan, drop the can in the water and go to work on another car. Its concidered dangerous to put the can on the exhaust manifold or near the radiator fan to get some heat.

Nissan vans are bad here, even in hot weather.

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Give all the dirty details
and dont forget the LO & HI pressures
Year, Make & Model would be nice too

Fishbone on Thu October 04, 2007 10:54 AM User is offline

It worked! Put the remains of the 2nd can and the 3rd on the pick-up tube and into a bucket of warm water, and it flowed right in. I did crack the low side knob on the manifold to get some bleedback to clear the line prior to installing and bleeding off the yellow hose. Thanks for the input. Brrrrrrr......its cold inside that car. Hope it stays that way.

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