HI,
I have a 98 F150 75,000 miles and I noticed that the air conditioning was blowing hot air. I can turn it off at times and it will start to blow cold air but if I accelerate it will transition to hot air.

Could this be caused by the drive serpintine belt slipping? I haven't replaced it...still has the original belt. I opened the hood and I haven't noticed anything unusual about the belt. No squeeking or fraying.

I love my truck and this is the first issue I have had with it.

Thanks for your input.

 

Could be low freon, they sell a nice kit with a guage at autozone for $30. It could be your belt but I would think you'd be having other problems if that were the case. I don't know if its true with the newer stuff, but the ac is suppose to cut off under heavy acceleration.

 

Don't use the kit from AZ to check your refrigerant charge. You need to monitor both high and low side.

Unless you understand refrigeration, the a/c is best left to those who understand the system. If your belt looks good and is tight, that is most likely not your problem.

Turn the a/c on full force and see if the clutch on the compressor is kicking in. If it is the frontmost portion at the a/c compressor will be turning, if the clutch is not kicking in, then this portion will not be turning.

The most common cause of the clutch not kicking in is a low charge. There is a switch that interrupts the clutch circuit when refrigerant is low to prevent compressor damage.

Good luck,
Doc

 

Your blend door runs off vacuum. The vacuum drops, almost to zero, when you punch the accelerator. That's why there is a vacuum accumulator. Could it be the blend door adding heat when your vacuum drops off as you accellerate?

 

The AZ kit works fine. The only reason to to measure the high side is to check the health of the compressor. I've been doing my own for over 20 years now.

And on the vacuum reservoir (accumulator), which you have to remove the right front fender to get to. That sounds like a good theory, but wouldn’t he be having other problems, no floor heat, trouble codes etc?

 

I will check the clutch today, since it was getting dark last night. Over the phone, my dad thought it was the freon as well but I thought at time the air would stay cold until I change the air setting from 'max air' to 'air', then it would start throwing out hot air. Other times, it seemed to be tied to acceleration.

Thanks for the posts, it gave me a few things to look at. I will check the truck out today.

 

Son, does it just blow non airconditioned air or does it blow hot as in heater hot?

 

Sorry...been busy lately. The wife is painting the house. I haven't had a chance to take it anywhere to have the freon checked. Today it seems that the vent is blowing hot air(air conditioning off). No matter what position, it is blowing hot air. Could it be the switch?

 

Replace the switch. I had similar problem $13 for switch.
Please note that the switch, even new, can not be turned quickly.
You have to turn it slowly. Have degree in EE and I can't figure it out.
No logical reason. Try the switch first, turn it very slowly at all times....

 

Or just the ****, They crack. Pull the temp **** off and look for a crack on the backside that fits over the metal post. If its cracked you wont be able to turn the post and it would be stuck on whatever temp it sits at. Simple fix, happened to me.

Don

 

I have a 97 f-150, a/c not working, tried to charge & it won't take it, noticed the compressor isn't kicking in. How do I check the clutch? Got my truck in 98 with 50,000 miles and now have 225,000. I love my truck and will drive it with-out a/c but it isn't as much fun. thanks for the help.

 

...Welcome young-g-ma, to Ford Truck Enthusiasts! Please read the Guidelines, it will help you to navigate through and understand this site.
Stick around someone will be by shortly to answer your question.
We are happy you have chosen the best source for Fords!

Enjoy FTE....and
JOIN CLUB FTE -SUPPORT THE FORUMS!
…..See you on the boards.

 

When I read about all the blend door problems I automatically assumed that my symptoms pointed in that direction - the $1000 repair. I saw the post about using a pin in the actuator shaft to engage the door mechanism but when I started to remove my glove box and check the actuator things did not really look like the pictures. I came back on this forum and got into the right section pertaining specifically to F150s and happened to see the posts in this thread about checking the switch and even the ****. Lo and behold my **** is broken where it engages the D shaped shaft of the switch. If I pinch the **** and turn slowly the temp changes through the range so I will not get too hopeful but I will pick up a new **** and try that first. Would it be a good idea to squirt some Tri Flow or some other lube to make sure the switch is not binding?

Thanks for the pointers - I wonder if I had left the truck at the dealer when I am on vacation in a couple of weeks if I would have come home to a new plenum box and a $1000 bill?

 

Do not squirt anything in switch. Turn it slowly and live with it, it works. I have done it for 2 years now, only an irritation. Ford should tell us why it works that way.

 

When does it blow cold air?? I've seen temp blend door actuators fail causing your system to blow hot except in max a/c mode. switch it to max and let me know what happens. I'm trying to remember if the f-150's have it, I think they do. There should be a water control valve in the heater hoses. it;ll be a black plastic valve with a vacuum line going to it. if it's equipped, (and I think it is) you can also disconnect that line and see if it blows cold. (this valve shuts off flow to the heater core in max mode) The blend door actuator is located under the middle of the dash, behind that black plastic cover. I'd test for power to the motor, or even just pull it down leving it connected, watch to see if it moves when you change the temp. you can try and put a stethoscope on it to and listen. if you don remove it, use an inspection mirror and check to make sure the blend door itself isn't broken. I'ts not trypically an issue with the f series that I've seen, but explorers/rangers are notorious for that. But just to be on the safe side, I'd chek it out. Lemme know what you find!