Bug or feature?
Thread Starter
|
Freshman User
Joined: May 2008
Posts: 44
Likes: 0
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
Posts: 6,473
Likes: 4
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
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
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.
Thread Starter
|
Freshman User
Joined: May 2008
Posts: 44
Likes: 0
Trending Topics
Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 12
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.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Lead Driver
Joined: Nov 2002
Posts: 9,555
Likes: 40
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
Likes: 13
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.