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Why less R134a?

Dereck on Mon October 20, 2008 5:00 PM User is offlineView users profile

Year: 1992
Make: Lincoln
Model: Town Car
Engine Size: 281ci
Refrigerant Type: R134a (now)
Country of Origin: United States

Hi Guys

As an air conditioning noob I would like to know why it appears some people say to use less R134a in a system that was originally charged with R12?

Regards

Dereck

TRB on Mon October 20, 2008 6:12 PM User is offlineView users profile

R134a has a higher operating pressure. Refrigerant needs to be converted from a gas to a liquid. The higher the high side pressure the harder it is to do this. Options are to get a more efficient condenser or some will undercharge the system. I don't suggest undercharging as you lose the ability to carry the oil back to the compressor.

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Dereck on Thu October 23, 2008 4:54 PM User is offlineView users profile

Quote
Originally posted by: TRB
R134a has a higher operating pressure. Refrigerant needs to be converted from a gas to a liquid. The higher the high side pressure the harder it is to do this. Options are to get a more efficient condenser or some will undercharge the system. I don't suggest undercharging as you lose the ability to carry the oil back to the compressor.

Hi TRB

Thank-you for your reply.

I have just fitted a new compressor, suction acumulator, orifice tube and low pressure switch, charged with 40 ounces of R134 and 7 oz of PAG 46 oil the quantities originally specified by Ford so it's probably a good thing I fitted two electric cooling fans switched (via a relay) by the low pressure switch as well

Regards

Dereck

rm32644 on Tue November 18, 2008 11:50 AM User is offlineView users profile

How did that work out for you? Be aware that too much R134a charge can result in too high of condenser pressures.

Dereck on Sat March 21, 2009 9:12 AM User is offlineView users profile

Quote
Originally posted by: rm32644
How did that work out for you? Be aware that too much R134a charge can result in too high of condenser pressures.

Hi Rm32644

It works really well, with an ambient temperature of 75 - 80 degrees I get 40 - 43 degrees from the center registars.

Regards

Dereck

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