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Change Compressor Model

ChemE on Fri April 18, 2008 9:13 PM User is offline

Year: 91
Make: Ford
Model: Mustang
Engine Size: 5.0
Refrigerant Type: R12
Country of Origin: United States

This car has a 6P148 compressor. The low side pressure is kept above a minimum by cycling the clutch on and off. It is effective, but sloppy in my mind. With the suction pressure ranging from 25 to 45, it does not keep the air at as low a temperature as I would like. The temperature ends up being lower if I speed up the fan or it is hotter, because the clutch does not have to disengage and send the evaporator pressure up to 45.

Another car I have has a GM V5 with a control valve, which is a lot smoother and more appealing to me as being a better answer to regulating the pressure and flow.

Some day if that compressor goes bad, I would like to replace it with one like the V5 that has a control valve. Does anyone know of a model with a control valve that is similar enough to the 6p148 to make mounting it and connecting the hoses practical?

There are no real problems with the system, although I had to add a can a few years ago. I recently added some UV dye so I can find the leak if it gets worse. This is just long-term thinking. Thanks for any ideas.

jdjam on Sat April 19, 2008 12:38 AM User is offline

Although not the best system in the world, it shoud be performing well if everything is adjusted or working properly. I have the exact same setup in my '89 Mustang 5.0.

Do you have any high-side pressures you can post?

Are you running the original fan clutch? Replacing my worn-out fan clutch helped tremendously in reducing high-side pressures.

If your cut-out pressure is 25 psi, you might be able to get by dropping that one or two psi without freezing the evap if you are in a drier climate.

My 6P148 pumps quite well at 18 years. What are your vent temps?

These guys on the forum are extremely experienced and helpful. Listen to them and they will guide you. I just wanted to share my thoughts as I have the exact same setup.


ChemE on Sun April 20, 2008 12:14 AM User is offline

Thanks for the post.

Sorry, I did not explain my request well.

The system works fine. I just don't like the cycling clutch design. It changes the sound of the engine idling.

I guess the cycling clutch is the standard though as my 2001 Ford does this also. I will try to go back to ignoring it. Maybe it is a little more noticeable with the engine starting to get tired.

bohica2xo on Sun April 20, 2008 11:10 AM User is offline


CCOT systems are cheap, bang-bang control stuff. They are not especially effecient, and the performance can be all over the place.

Your old V5 was an elegant solution by comparison. Constant run, variable displacment, with evaporator pressure control. Coupled with a TXV this is a very smooth, effecient system.

It would be a lot of work to fit a V5 / V7 in place of what you have on your fox body. It could be done but you would be fabricating new brackets & hoses, adding a TXV etc.


"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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