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Hello all. I have a 2008 f250 lariat crew cab v10. The air conditioner on it has not been working. It blows mildly cool air, and barely feels cool as the temperatures reach closer to 80-85 degrees. The system is fully charged, and the truck also has a heater shutoff valve that is off. The ambient temperature is 80 degrees, and the low side is right around 30psi and the high side is about 220 psi. So the high side is normal, but the low side is low. Any ideas on where to start. Thanks
I'd suspect a jammed or stuck or otherwise inop temp blend door also. With the system on VENT, do you have full temperature control from a bit higher than ambient through HOT when varying the temp control through its full range with that heater valve open?
Your gauge readings look pretty good, you SHOULD have 35-40 degree air coming out the vents. The low-side line coming out of the TXV should be very cold, mid-30s.
I'd suspect a jammed or stuck or otherwise inop temp blend door also. With the system on VENT, do you have full temperature control from a bit higher than ambient through HOT when varying the temp control through its full range with that heater valve open?
Your gauge readings look pretty good, you SHOULD have 35-40 degree air coming out the vents. The low-side line coming out of the TXV should be very cold, mid-30s.
the line coming out of the orifice tube is definitely cold. I don’t have an infrared thermometer to check, but it feels about as cold as any line I’ve felt on any other vehicle. Can you elaborate on the first part? This truck doesn’t have a vent mode that I’m aware of, and the hvac controls that the truck has are the dual buttons on each side with a small screen on the center.
The goal is to use a setting that doesn't have the A/C compressor running. The discharge air should be pretty close to ambient. If the air is still warm with the A/C compressor off, that would confirm a blend door problem. Usually, the floor only and panel only discharge settings are the only 2 that don't run the A/C. If you have any doubt, you could pull the fuse for the compressor.
With regards to the blend door, is it usually due to the actuator or the blend door itself? Is there a way to inspect the blend door relatively easily?
The goal is to use a setting that doesn't have the A/C compressor running. The discharge air should be pretty close to ambient. If the air is still warm with the A/C compressor off, that would confirm a blend door problem. Usually, the floor only and panel only discharge settings are the only 2 that don't run the A/C. If you have any doubt, you could pull the fuse for the compressor.
pulled the fuse for the ac, and let the truck run a while (it was at operating temp) and the air from the blower never seemed to get particularly hotter than ambient
Did you perform the test as I described it back in post #4? I see no report that you varied the temperature control. Did you?
I hadn’t varied the temp, so I redid it. Because the truck doesn’t have a vent mode, I left it on ac and pulled the relay so the compressor wasn’t engaging. I also left the heater valve OPEN as you said. When I did that, the temperature when set at the lowest seemed to be pretty close to ambient temperature, and at the hottest setting got very hot. I think that is how you were saying to test it?
also, if I’m thinking right, even if the blend door was malfunctioning and mixing in hot air, wouldn’t the water valve negate those effect? Thanks for all your help
From what you've said, I'm having a hard time thinking of a logical reason for the air not to be cold. I know you said the line to the avaporator is cold after the orifice tube. How about the line on the suction side of the evaporator?
The auction line coming out of the evaporator I would say is cool to the touch, not as cold as the one coming into it from the orifice tube, but definitely cool to the touch.
one thing I noticed though is the line coming from the orifice tune into the evaporator goes right above the exhaust manifold, and there’s no insulation of any kind on it. Not sure if that could artificially heat the line and make it not work as well.
Well, got busy with work and had to put the truck on the back burner and use it as is, but once I got time again got it figured out. Better late than never. Replaced the orifice tube, it looked fine but replaced t since I already had it out. Vacuumed down and recharged. Air still wasn’t getting cold. I did notice though that the compressor was kicking on and off a lot, way more than it should. So I ran the compressor manually, and it froze the lines up so I knew it was fine. I did notice once I kept it running, the high side pressure kept rising…peculiar. Then misted water over the condenser and high side pressure came down, and both pressures were low and thus that’s why the ac wasn’t getting cool and kept cycling. However the excessive pressure needed fixed to be able to finish filling. I felt the fan clutch and it felt too loose to me and after running it I never really heard it come on like it should. Replaced it and my high side pressure stayed down. The truck then took another 12 oz of refrigerant and pressures are perfect, the compressor doesn’t constantly cycle, and the truck gets COLD. Sorry for the late update but maybe will help someone.
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