Strange AC problem & its 95 outside HELP!

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Aug 9, 2009 | 02:15 PM

okiepc1

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From: Oklahoma

Strange AC problem & its 95 outside HELP!

AC works just fine at idle, cold and blowing good, problem is going down the highway under power, no cold air, but if you coast, plenty of cold air. It acts as if something closes off under power and reopens when coasting.

Gauges check out, 38 low, 280 hi what could the problem be? I cannot find a vacuum leak.

Thanks for any help
okiepc1

85 F150 302 AT Explorer

Aug 9, 2009 | 02:37 PM

ctubutis

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From: Denver Metro Area, CO

Sounds to me like a lack of a fruit juice can or other vacuum reservoir (some trucks use
softball-sized black, plastic ***** for the HVAC vacuum), these are the things that
retain/store vacuum during times of little to no vacuum supplied by the engine, e.g. during
heavy acceleration. Or, perhaps a vacuum leak affecting the vacuum motor that operates
the HVAC system.

Aug 9, 2009 | 04:36 PM

okiepc1

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From: Oklahoma

You verified my suspicions. my pickup has both, the fruit can and the ball so it looked like the black plastic ball ran the show for the ac. I had an extra reservoir from some other application, hooked it up & nice cold air uphill or down.
, problem solved

Thanks for your input

okiepc1

Aug 15, 2009 | 02:09 PM

Cnorth6525

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From: Texas

check your vacum hoses on the firewall closest to the blower motor. Cap the middle one and the left one goes to the blower motors, and the right one goes to the intake.