Bug or feature?
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Bug or feature?
In my 1989 F250 2wd, auto, when pulling a trailer uphill, my A/C seems to stop. Does it do this on purpose to give the truck all available power or is the truck using all available power and killing the A/C?
Post Fiend
Joined: Apr 2004
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From: Lafayette, IN
It's all about the vacuum. Under hard throttle/load/acceleration, the engine doesn't create much vacuum, so as soon as the pressure comes up in your vacuum reservoir, the blend doors in the dash go to their default position (defrost), so you don't feel air from the mid-level vents.
Jason
Jason
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Joined: Jun 2006
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From: Ottawa, Ontario
Yes.. that points to a vacuum leak.. though the OP made no mention of the air switching to another vent in his case.
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Lead Driver
Joined: Aug 2006
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From: Sand Lake, MI
The wife's explorer does the same thing, towing a camper through the mountains on a trip out west had it happen to us for the first time.
I thought oh great, on vacation hundreds of miles from home out in this heatwave and the air is going to pick now to die?
Long, steep uphill climbs at full throttle or close to it would cancel the A/C and yea I think it did even switch to defrost when it happen. Backing off the throttle a bit once cresting the hills and everything returns to normal. We got some hills here but nothing that long or steep so we never had it happen before that.
I thought oh great, on vacation hundreds of miles from home out in this heatwave and the air is going to pick now to die?
Long, steep uphill climbs at full throttle or close to it would cancel the A/C and yea I think it did even switch to defrost when it happen. Backing off the throttle a bit once cresting the hills and everything returns to normal. We got some hills here but nothing that long or steep so we never had it happen before that.
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Brett Foote
Lead Driver
Joined: Nov 2002
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From: Concord, NC
Not all vehicles have an A/C WOT cutout. That was one thing that I added when I converted to mass air using a Mustang computer. The Mustang computer had the feature, my stock truck computer did not. Even then, it just disengages the compressor -- it doesn't turn off the whole system (i.e. the fan still runs).
Post Fiend
Joined: Oct 2003
Posts: 6,214
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From: New Jersey
Some Fords turn off the AC compressor when the coolant temp gets too high. All three times my Intercepter overheated the AC compressor cut off while the temp gauge was at it's normal "4 bars" (digital cluster) then within 10 seconds the gauge jumped to "all bars", the knocking starts, the power goes away, then another 10 seconds later the engine shuts down.
Even if you're on the highway doing 75.
Definately the most bone-headed design there is.
The cause of all this? The electric fan was occasionally drawing over it's 50A fuse, and popping it, thus no fan.
Even if you're on the highway doing 75.
Definately the most bone-headed design there is.
The cause of all this? The electric fan was occasionally drawing over it's 50A fuse, and popping it, thus no fan.
