1997 Ford Crown Victoria AC shuts off

Tiny
DAOVIC
  • MEMBER
  • 1997 FORD CROWN VICTORIA
  • V8
  • 2WD
  • AUTOMATIC
  • 170,000 MILES
The AC shuts off above 90 degrees. Filled the Freon with the proper pressures 45-55 psi. After running, it shut off with low pressure above 165 psi. Brought psi down to avoid damage to the low side of the system.

Please advise. From what I have seen, problem may be an inoperative expansion valve. Where is it, and how is it replaced? Is this a DIY, or Shop required?

Never used this site before.

Thanks
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Saturday, August 1st, 2009 AT 6:32 PM

5 Replies

Tiny
BUDDYCRAIGG
  • EXPERT
I'm going to have to ask you a lot of questions.
Even though you said a lot of stuff, you left a few little things out with each statement.

The AC shuts off above 90 degrees.
When what is above 90 degrees?

How does the AC shut off?
Is the compressor clutch disengaging?
Or
is the compressor still running but the air out the vents is warm?
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Saturday, August 1st, 2009 AT 11:16 PM
Tiny
DAOVIC
  • MEMBER
Buddy -

The ambient temperature is about 90 degrees. The AC cools until running for a while, then shuts down.

The compressor shuts off.

I checked the pressure for the first time yesterday. This was done after filling the low pressure side until it reached 50(+ or -) psi, with the ambient temperature around 85. I ran the car for a while and the compressor shut off. I searched the Internet for similar problems and found that the cause may be the expansion valve/orifice. I checked the pressure (low side) and it was around 165 psi. Seeing that this was the low side and did not want damage done, so I reduced the pressure back to around where it started before filling (around 25-30 psi).
Thanks,
DAOrner
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Sunday, August 2nd, 2009 AT 10:50 PM
Tiny
BUDDYCRAIGG
  • EXPERT
If the low side was at 50 with the compressor running, then you have 3 possibilities.

The compressor valves are weak.
The expansion valve is not closing.
You have too much freon in the system.

If you can tell me what the high side readings are, it will help rule out having too much freon.

The low side can get to 165 when the engine is off and the under hood temps are in the 220F range

And PS, 25 30 is where you want the low side to be with the compressor running.
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Sunday, August 2nd, 2009 AT 11:25 PM
Tiny
DAOVIC
  • MEMBER
The engine was running with the low side @ 165 psi and the compressor shut off (AC still on).

The hood was open, outside ambient was 85 degrees. Temp under hood was well under 220 degrees.

The instructions on the can show low pressure 45-55 psi @ 85 degrees ambient.

Do not have a dual guage (simple low side refill kit).

Thanks
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Sunday, August 2nd, 2009 AT 11:45 PM
Tiny
BUDDYCRAIGG
  • EXPERT
That would be for a charged system, without the compressor running.

I just checked my quickie chart and r-134 would be 165psi at 118F without the compressor, so that's totally believable.

Go get yourself a cheap set of gauges.
I paid $40 for my first set and they lasted 6 years.(Other than the plastic knobs cracked and had to be replaced.)

right now, we dont know why the compressor is shutting off. Knowing high side readings would help narrow that down.

The high side could be getting too high and a pressure switch is tripped,
or
the evaporator is freezing up
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Monday, August 3rd, 2009 AT 12:03 AM

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