AC help .....
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Freshman User
Joined: Jul 2009
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From: DFW area
AC help .....
got a 99 f250. air works fine and blows cold but everytime I come to a stop or slow it starts blowing just plain air (not hot). heard I should clean the condenser of dirt and bugs. Also was told to add freon. I thought freon stayed put unless you have a leak or something like that. If so, where do I look for the leak. anyone else having this issue. Thnx in advance.
Fleet Mechanic
Joined: Feb 2006
Posts: 1,776
Likes: 5
From: Lorain County, Ohio
"Add Freon" is an answer you will hear any time you mention any problem with AC. Some folks think that is the very first thing to try if you have problems. 
To know for 100% certain, you will need a manifold gauge set to see what the system pressures are doing, but you can try some things to help you diag the problem without the gauges.
Your symptoms indicate restricted airflow through the condenser. This will be either debris in the condenser or a weak/failed fan clutch. The condenser can "look" clean and still be full of debris down in the fins.
Have a friend spray the condenser with water from your garden hose while you sit in the cab with the engine at @ 1500 and the AC on. If it starts cooling better, something is reducing the airflow through the condenser. If not, there is another problem and you need the gauges.
Assuming it cools better with the water test (I suspect it will), soak the condenser thoroughly with a good soap solution like Simple Green, Purple Power, etc. keeping it wet for about 10 minutes. If you can, loosen the radiator, pull it back and flush the condenser from back to front with the garden hose. Flush out the radiator fins as well.
Now, drive around for a few minutes to dry the condenser and radiator. If the AC works well now at idle, you've fixed the problem.
If it still wheezes out at idle, replace the fan clutch with Mororcraft unit or Hayden HD unit. Avoid the cheap parts store fan clutches.
At 10 years I suspect that you will end up replacing the clutch, that's actually the expected life span. Lack of AC cooling at idle is the very first sign of a failing fan clutch and will happen long before the engine temp is effected.
To know for 100% certain, you will need a manifold gauge set to see what the system pressures are doing, but you can try some things to help you diag the problem without the gauges.
Your symptoms indicate restricted airflow through the condenser. This will be either debris in the condenser or a weak/failed fan clutch. The condenser can "look" clean and still be full of debris down in the fins.
Have a friend spray the condenser with water from your garden hose while you sit in the cab with the engine at @ 1500 and the AC on. If it starts cooling better, something is reducing the airflow through the condenser. If not, there is another problem and you need the gauges.
Assuming it cools better with the water test (I suspect it will), soak the condenser thoroughly with a good soap solution like Simple Green, Purple Power, etc. keeping it wet for about 10 minutes. If you can, loosen the radiator, pull it back and flush the condenser from back to front with the garden hose. Flush out the radiator fins as well.
Now, drive around for a few minutes to dry the condenser and radiator. If the AC works well now at idle, you've fixed the problem.
If it still wheezes out at idle, replace the fan clutch with Mororcraft unit or Hayden HD unit. Avoid the cheap parts store fan clutches.
At 10 years I suspect that you will end up replacing the clutch, that's actually the expected life span. Lack of AC cooling at idle is the very first sign of a failing fan clutch and will happen long before the engine temp is effected.
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