Air Conditioning
It's a Van Gogh
Joined: Feb 2010
Posts: 7,813
Likes: 1,335
From: Elk Grove, CA
There is a max AC mod that works well, still rocking it on my truck.
Wow...REAL Air Conditioning!! - Ford Truck Enthusiasts Forums (ford-trucks.com)
Wow...REAL Air Conditioning!! - Ford Truck Enthusiasts Forums (ford-trucks.com)
Tuned
Joined: Nov 2018
Posts: 292
Likes: 64
From: PA
Cheap fix to improve on AC is install a ball valve on engine heater hose and close it in the summer.
Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
Have you gone over the duct work checking for leaks. At their age it's a good possibility the foam that seals the joints has broken down some. I went through mine with a roll of rope caulk and plugged any air leak I could find. It made a noticeable difference in felt temp and force at the vents. The evaporator box was the biggest leak point, especially after opening it when I replaced the core. Another thing noticed by more than a few or us is the blower performance after switching to an aftermarket fan. They just don't seem to move as much air as the original Motorcraft blowers do.
More Turbo
Joined: May 2016
Posts: 717
Likes: 9
Next put a RED Orifice Tube in the A/C. Mine blows about 54* Air Temp
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Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
A couple other things came to mind. You might check the fresh air vent door is closing during max AC. Up under the dash in the passenger footwell is the vacuum control actuator. Check that the vacuum line is hooked up and the door closes when in max AC. The blend door is another possibility and a somewhat common one. If the actuator has quit or even just dirty connection it can allow hot air from the heater core in w/ the cool and just kill the AC performance.
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Trailering
Joined: Jul 2016
Posts: 23
Likes: 4
Not much you can do about that. However, put a vacuum solenoid into the Heater Core Line and connect it to the white vacuum line under the dash. When in MAX A/C the Heater Hose Valve is CLODED Automatically
Next put a RED Orifice Tube in the A/C. Mine blows about 54* Air Temp
Next put a RED Orifice Tube in the A/C. Mine blows about 54* Air Temp
Laughing Gas
Joined: Apr 2006
Posts: 1,121
Likes: 267
From: Middle Georgia
IIRC last year some guys talking about an addative that made the AC perform better. Was going to do it to mine, but never got around to that or installing the bypass valve. I think @Sous and @SkySkiJason were both in on the conversation since I recall it coinciding with discussion about one of the NGA G2Gs.
Cargo Master
Joined: Sep 2015
Posts: 2,860
Likes: 365
IIRC last year some guys talking about an addative that made the AC perform better. Was going to do it to mine, but never got around to that or installing the bypass valve. I think @Sous and @SkySkiJason were both in on the conversation since I recall it coinciding with discussion about one of the NGA G2Gs.
On edit: x3 on the bypass valve, a 3/4 PEX ball valve fits perfectly in the line going to the heater core. Simple , cheap quick fix and it works.
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
Banned
Joined: Dec 2018
Posts: 3,541
Likes: 458
As far I knew the low pressure switch on the accumulator was just a "dumb" switch that cuts the compressor off if low side pressure drops too low. What specific pressure that is, I'm not sure. There is a PID in ForScan for it called "ACCS" which basically just displays "off" when the system is off and "on" when one of the AC or defrost settings is selected with the dash **** to cut the compressor on. It does not report real time pressure readings to the PCM I was disappointed to learn like the MAP sensor does, or an aftermarket boost or fuel pressure PID, which would be helpful for diagnostic purposes on a cranky system that isn't working right (like mine). Same with the high side switch.
Trailering
Joined: Jul 2016
Posts: 23
Likes: 4
Normally when the low side gets to about 25 psi, the compressor cycles off. This is to prevent freeze up of the evaporator, cycle off the compressor at very high rpms and shut it off if there is low charge.
If you have to downshift going up a hill or have low gearing and high rpms on the freeway it can cause your compressor to constantly cycle.
I replaced the low switch with one that I can adjust with the adjustment screw to lower it down to say 19 psi. The OEM 25 psi is about 29 degreesF at the evap core when it cycles off. So your air coming out will be at best 38 degrees with low humidity. Im in PHX so humidity is LOW, I can get down to about 20 theoretical degrees at the evap at about 19 psi. The truck does not normally run that low however unless high rpms or low blower. My air is real cold about 32 when cruising. It does nothing for idle.
If you have to downshift going up a hill or have low gearing and high rpms on the freeway it can cause your compressor to constantly cycle.
I replaced the low switch with one that I can adjust with the adjustment screw to lower it down to say 19 psi. The OEM 25 psi is about 29 degreesF at the evap core when it cycles off. So your air coming out will be at best 38 degrees with low humidity. Im in PHX so humidity is LOW, I can get down to about 20 theoretical degrees at the evap at about 19 psi. The truck does not normally run that low however unless high rpms or low blower. My air is real cold about 32 when cruising. It does nothing for idle.