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NKENN on Fri December 04, 2009 8:47 PM User is offlineView users profile

Year: 2005
Make: FORD
Engine Size: 3.0L
Refrigerant Type: R134A
Ambient Temp: 85
Pressure Low: HIGH
Pressure High: NORMAL
Country of Origin: United States

The Ford Freestyle and 500 both use block type TXVs attached directly on the evaporator at the firewall in the engine compartment. They also use variable displacement scroll compressors that pretty much run all the time when the AC is turned on. The compressors run continuously in the variable displacement mode to reduce changes on the engine load (and thus prevent drivability problems when they cycle on and off).

I have read on several forums where Ford 500 owners have had problems where the repair shops misdiagnosed the problems and replaced the wrong components. Their symptoms were that the AC did not cool when the car was idling and cooled sufficiently when the car was running at highway speed. Most of the time the shops replaced the TXV and that didn’t correct the problem. Then, they replaced the compressor to finally correct the problem.

I had a similar problem on my daughter’s 2005 Freestyle. It would stop cooling at idle and cool slightly at highway speeds. At the time, I didn’t know that the vehicle had a variable displacement scroll compressor. I was getting a normal high-side pressure and a high low-side pressure and, I too misdiagnosed the problem as a stuck open TXV.
My question is: Is there any way to properly diagnose this system using a manifold gage set or, did I just draw the wrong conclusion from the available data. If so please explain where I went wrong. I don’t want to make the same mistake again.


Chick on Sat December 05, 2009 7:55 AM User is offlineView users profile

Your pressures, high and normal don't tell us much.. We need the numbers, also make sure the compressor is running when you take them... Don't go by "others" diagnosis as you may have a different problem from theirs.. Cooling "slightly" while moving may also indicate a low charge.. start with the pressures (numbers)..and be sure the compressor is engaged when you take them..hope this helps..

Email: Chick


Freedoms just another word for nothing left to lose

NickD on Sat December 05, 2009 9:02 AM User is offline

Pressure Low: HIGH, Pressure High: NORMAL can be interpreted as the compressor isn't even running, in particular if the low and high side pressures are identical. Pressure readings for diagnostic and even charging are taken with AC on, blower at maximum, doors opened, and the engine running at 2,000 rpm. But also good to know the pressures at idle. Specify the ambient temperature and RH as well. If you say both pressures are at zero, but don't tell us the temperature is -30*F, can't be of much help. We may think your system is empty when indeed, these pressures, zero, are perfectly normal at sub zero temperatures.

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