AC still giving me issues. Help
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AC still giving me issues. Help
I own a 99 F-250 PSD with 144,000 miles. I am having a repetitive problem with the AC. It will blow cold at a high RPM then go warm/humid while I am at idle. I had the freon pressures checked at the shop and the level was low so they added 1lb to the system along with dye. They checked the sysytem for a leak after I drove it for a few days with none found. Problem still occuring. They replaced the low pressure cycling switch and told me that since it is a black truck with dark interior it will soak up the heat (duh) and will take longer to cool. Okay, I might beleive that if it was always that way but it has not. THis is the second low pressure swith changed. THe compressor will engage and disengage, and i cleaned the coils last night, but problem is still happening. I installed a Microtuner three years ago, but that should not cause this proble, should it? Any ideas, help! 
Fleet Mechanic
Joined: Feb 2006
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From: Lorain County, Ohio
Have you checked the operation of the cooling fan? This is a classic symptom of a weak fan clutch. If it uses a fan clutch, replace it with a NEW one from FORD. Avoid the aftermarket ones on this truck. It sounds like the system is cutting out due to high head pressure due to low airflow. Also flush the exterior of the radiator and condenser cores. Debris can block airflow and you'd be surprised how much will flush out of an apparently clean condenser.
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Change out Compressor?
I havediscussed the clutch fan and compressor with two seperate mechanic shops and they tell me the same thing, "it works fine when we live it sitting". Well yes it does when you crank it up, and don't drive off. THey are correct, but the problem occurs after I have driven it for a few miles. I have priced compressors with clutch fan online and have reached the point that I will cahnge the whole thing out myself. The question is how hard is that task? Do i need to evacuate all of the freon to do this? Any thoughts or guidance on these questions?
S
S
Fleet Mechanic
Joined: Feb 2006
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From: Lorain County, Ohio
Originally Posted by scdkmd11
I havediscussed the clutch fan and compressor with two seperate mechanic shops and they tell me the same thing, "it works fine when we live it sitting". Well yes it does when you crank it up, and don't drive off. THey are correct, but the problem occurs after I have driven it for a few miles. I have priced compressors with clutch fan online and have reached the point that I will cahnge the whole thing out myself. The question is how hard is that task? Do i need to evacuate all of the freon to do this? Any thoughts or guidance on these questions?
S
S
http://www.projectresponder.com/fan-clutch~4~105.htm
Fleet Mechanic
Joined: Feb 2006
Posts: 1,776
Likes: 5
From: Lorain County, Ohio
Originally Posted by scdkmd11
Thanks for the guidance. I am not an AC wiz, but apparently the shops I have brought my truck to are not either. S
I generally recommend that if a fan clutch is over 5 years old, it should be replaced with an OEM part if working on an AC system. I follow this advice on my personal cars. I've found that many aftermarket types cause AC problems even when new.
I hope this helps.
