I have a 96 f150 pretty much anytime that i accelerate my ac cuts out. Sometimes it doesnt cut out completely but stops blowing on the dash vents and blows on either the floor or defrost vents. when i let off the gas it starts to blow fine again. what could cause this???
What motor do you have? It may be normal depending on motor size.
Looks like the 300 6 is the only one that had one up to 95, can't find the same info on the OBD II system so far.
So if the A/C turns off at WOT and you have a 4.9L (300 CI) its a good chance its normal. A/C is shut off at wide open throttle to give full power, is also delayed at "start up" 15 seconds.
"Air Conditioning WOT off relay"
If it does it really easy, under even very moderate acceleration yea you may have a vacuum leak or a bad cut off switch or both making it worse.
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87, 94, 95 F250
89 Bronco II
96 Explorer
Hey i just noticed the other day mine does the exact same thing! I have the 300 too. But it didnt used to do this before.... also my heater doesnt work!
Long periods of high-load (low or no vacuum, like going up a long hill) will cause the vacuum reservoir to deplete, at which time the vacuum-operated blend doors will move to the default position (defrost). It doesn't even have to be WOT, and it will happen in any of these engines.
Jason
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-1990 F150 XLT Lariat LB 302 2wd AOD 3.55 open (former work truck, gone, but not forgotten)
-1993 F250 XLT xcab LB 351 2wd E4OD 4.10 open (parked, tranny issues)
-1989 Mazda B2200 SB 2.2L 2wd 5-speed (work truck)
i have a 5.0L V8 i found a diagram for the vac lines but there are i think 12 seperate vac lines on that engine the other motors that were made that year had only 4 to 6 could it be any of those line are is there a particular line that it might be?
Find the HVAC housing hanging on the firewall on the passenger's side. On the top of the housing will be a rubber boot with a bunch of wires and a couple vacuum lines passing through it. Only ONE of these lines will go to the engine and the rest will go to the underhood HVAC servos. It will have a small check valve in it. That's your main supply line for the HVAC.
In a good, sealed, system, the doors should NEVER return to default unless the selector switch on the dash is moved. The check valve in the supply line will maintain system vacuum and hold their position. I just did a body swap on my '93 and the doors were still in the "vent" position until I unplugged the vacuum connector under the dash - 3 WEEKS after the engine was last running and 2 WEEKS after the cab was removed! When I opened up the system, they returned to default.
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Speed kills. I'm just building a better way to die.
