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1978 Ford LTD with A/C issue


Guest WisconsinGuy
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Guest WisconsinGuy

I have a 78 Ford LTD with a 351m. Having an issue with the A/C. 

 

At idle the air works perfect. Blows ice cold. Under acceleration it gets warmer. Still somewhat cool air but not cold enough to keep up when it's extremely warm out. Any ideas?

 

Thanks! 

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I would guess a  problem to the door that regulates the temp. The ac probably working fine but the door is opening to let in warm air. If it is vaccum operated you are loosing the pressure to control the door.

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That model year is too vintage for the a/c compressor to "cut-out under load", so that's out, as far as I know.  Is it letting outside air in (on Recirculate) or just getting warmer?  Is the water valve vac operated or operated with a cable? 

 

Can you duplicate these operational issues with the engine loaded against the foot brake, in gear?  IF, as you throttle into the engine with the foot brake firmly applied, the a/c compressor stops cycling, or if the warmer air starts with lower manifold vacuum, then those would be two things to investigate.

 

If you restrict the heater feed hose with a pair of vice grips or similar, does it still get warmer air?

 

Please keep us posted on your progress.

 

NTX5467

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