A/C issue?
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A/C issue?
So i noticed today while driving on the highway to and from work, and even around town that when i get to the middle- top end of a gear mostly 3-4 the A/C air coming out of the vents will slow down and shut off untill i lay off the gas. Basically the faster i go the air shuts off. I dont think this is normal. Any help would be nice as the weather is getting to be hot and having the windows down doesnt cut it anymore. The truck is a 1996 f150 inline6 5speed 2wd.
Laughing Gas
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From: long island
sounds like a vacuum leak. does the air start to come out of the defrost when it stops coming out of the vents? pop your hood and look on the passenger side by the blower motor. there is probably a white vacuum line that got old and cracked and may be leaking.
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Ill go take alook now and see whats up under the hood. It doesnt come out of any other vents when it slows down. it just stops. I was thinking, and yes its kind of far out there, could it be the tension pully belt thing ( idk the exact name cause im a car noob) thats slipping on the compressor because when its on just vent and not a/c it stays on for the most part.
Senior User
Joined: Aug 2009
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From: Brazoria, Texas
Ill go take alook now and see whats up under the hood. It doesnt come out of any other vents when it slows down. it just stops. I was thinking, and yes its kind of far out there, could it be the tension pully belt thing ( idk the exact name cause im a car noob) thats slipping on the compressor because when its on just vent and not a/c it stays on for the most part.
Fleet Owner
Joined: Oct 2005
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From: Kentucky
Some great info and pics in this thread from another forum: A/C and/or heater stuck on defrost - FSB Forums
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Weird. Today it just stopped doing it.... It started to do it then just stopped. So I dont think ill worry about it until it happens again. But thanks for the help
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Lead Driver
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From: Sand Lake, MI
Its normal, the EEC cuts A/C under full throttle condition.
Even at that under full throttle engine vac drops sharply, dash venting requires vacuum to hold any setting other then defrost.
See here Ford Fuel Injection » Strategies, have a gander at the section "Full-Throttle Acceleration"
An excerpt,
All EGR functions are stopped and the canister purge valve is closed to ensure the exact air to fuel ratios desired. Smog pump air is dumped to atmosphere, air conditioning, electric fan, and all other high demand accessories are shut off to lessen the accessory drive load from A/C and alternator.
Even at that under full throttle engine vac drops sharply, dash venting requires vacuum to hold any setting other then defrost.
See here Ford Fuel Injection » Strategies, have a gander at the section "Full-Throttle Acceleration"
An excerpt,
All EGR functions are stopped and the canister purge valve is closed to ensure the exact air to fuel ratios desired. Smog pump air is dumped to atmosphere, air conditioning, electric fan, and all other high demand accessories are shut off to lessen the accessory drive load from A/C and alternator.
Lead Driver
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From: Sand Lake, MI
And just maybe at the same time the OP had been into that skinny pedal a little more then originally might have thought? Just maybe?
Anyway with that info a quick test ride should prove or disprove easy enough its normal operation or some other condition as the cause?
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I thank you sirs for the information, it has helped alot. And i do think i might have been into it a little more than i thought its very possible. (and highly likely) i had no idea about the full throttle adjustments and stuff. Ill read up on it. but it seems thats what it was.
Fleet Owner
Joined: Oct 2005
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From: Kentucky
FWIW my '92 F350 exhibited the same type issue when I first got it 2 years ago. After searching around on the 'net I narrowed it down to the little plastic reservoir on the side of the blower case. A previous owner had covered it in epoxy in an attempt to repair the cracks. I ended up using an unused portion of the dual chamber vacuum reservoir as a suitable replacement thanks again to the same PO who removed the TAB/TAD system.
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