Heating, Air Conditioning & Cooling SystemsDoes your heater blow cold air? Does your air conditioning blow hot air? Post your all of your technical issues related to your heating, heating core, air conditioning unit and controls here. Don't wait until it is to late to get these important vehicle functions fixed.
We have a 2003 F250 7.3 diesel. The air conditioner blows cold when we turn it on, but then in 5 minutes or 3 hours later, you just never know, it starts blowing hot air. Then it might start blowing cold again in 5 minutes or 2 hours. My husband thought he fixed it one day when he checked wires under the hood to make sure they were all connected securely and not halfway disconnected. After that we went almost one week without a problem and then, all of a sudden, it started up again with the same thing. So, I guess that might have just been a coincidence. My husband checked the fuses inside on the driver's side and they all seemed to be good. We've taken it to Ford, but they can't find the problem unless it's happening when they receive it. It has plenty of freon. Any ideas would be great appreciated.
Gas engines produce vacuum and it is used to affect vacuum actuators that control the direction of air flow through teh venting system of the truck. There is also an electrically controlled motor that affects the movement of a "Blend" door within the ductwork to permit air to travel through, or around the heater core.
Deisels don't create vacuum, but usually have a vacuum pump to create vacuum for these little actuators.
Other than that I believe that the systems are the same.
HEre are a number of threads that if you poke through them, you'll find enough info to understand how the system works, and probably narrow down the issue.
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BroncoJoe19
2006 Alt Fuel Jeep (electric)
'98 windstar 3.8L
'99 Crown Vic 4.6L
'90 Full Size Bronco 5.0L
I'm not a professional mechanic, take my suggestions with a grain of salt, or a cup of coffee
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__________________
BroncoJoe19
2006 Alt Fuel Jeep (electric)
'98 windstar 3.8L
'99 Crown Vic 4.6L
'90 Full Size Bronco 5.0L
I'm not a professional mechanic, take my suggestions with a grain of salt, or a cup of coffee
At the bottom of each post there is a little icon
Clicking it gives feedback to the moderators, and poster regarding which posts are most helpful.
The blend door actuator has a "feedback" potentiometer inside to tell the controller it's position. If the feedback pot sends back the wrong position, the controller goes hog-wild trying to move the temperature blend door. Also the actuators can break a plastic gear inside allowing overrun, or heck, the door itself might be broken. Seen 'em all.
__________________ 96 Explorer XLT Control Trac 4WD 4.0
96 Dodge Caravan Sport 3.0
94 Toyota Tacoma 22RE
88 Toyota Camry
63 Yale G61C I hope you have found this post to be helpful.
You don't know how much your response is appreciated. We are definitely going to check out the blend door, etc. Hopefully that will solve our problem. Will post as soon as we find out something.
We have a 2003 F250 7.3 diesel. The air conditioner blows cold when we turn it on, but then in 5 minutes or 3 hours later, you just never know, it starts blowing hot air. Then it might start blowing cold again in 5 minutes or 2 hours. My husband thought he fixed it one day when he checked wires under the hood to make sure they were all connected securely and not halfway disconnected....
Another idea...
When you say "blowing hot air" , does that mean the heater is on, blasting air that has been heated (like 180`f)? Or does that mean same as the outside air, the hotter the day, the hotter the air?
We might have an intermittent A/C compressor circuit. If so, the compressor is not spinning during the periods of A/c failure.
__________________ 96 Explorer XLT Control Trac 4WD 4.0
96 Dodge Caravan Sport 3.0
94 Toyota Tacoma 22RE
88 Toyota Camry
63 Yale G61C I hope you have found this post to be helpful.
I am interested to know if you found a fix for this. I have had the same problem for months. Had gauges put on it and they said everything was fine. Sometimes mine works great other times not at all. Definately a clutch shutting off problem, when it's running everything is fine. I believe it must be a power to the clutch problem. Seems that if I accelerate or at least shut off the auto overdrive it will engage the clutch again at least for a short time. Sometimes it will work for a couple hours without shutting off (usually on the highway), other times not at all. Sometimes it even works well at idle but that is when I have most of my problems. If anyone has and answer for this I'd sure appreciate hearing about it. Everyone I've talked to just scratches their heads. Thanks in advance, Richard
We took out the radio on our F250 and checked to see if the little plunger, located behind the radio, was working. The plunger opens and closes the vents and it was working, so that is not our problem. We visually checked all the wires and connections and everything else we could see, but nothing looked wrong. Our problem continues with the A/C blowing cold air when it feels like it. I said previously that it blew hot air, but I didn't mean hot like the heater was on. It just blows regular outside air and not cold air when the a/c decides to stop working.
i have seen this problem before with the superduty trucks. it is the compressor shutting off. the cause has been the high pressure cutout switch. it is located on the discharge line comming off the compressor-it is the smaller line that goes to the condensor located infront of the radiator. the only other problem that i have found with the ford compressors-fs10 models-is that the field coil for the a/c clutch gets weak and cannot pull the disc in to engage the compressor when it gets hot. next time your a/c shuts down leave the engine running and ck to see if the compressor is turning. if it is not carefully take a screw driver and touch the clutch disc-be very careful not to touch the fan with the screw driver. it the clutch engages or the screw driver sticks to the disc then the field coil is weak. if not ck the high pressure switch. disconnect the switch and use a paper clip to jumper the two wires together on the harness. the a/c compressor should then engage. i hope this helps.
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F250 a/c blows hot air then self corrects 
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