A/C air flow / cold intermittent

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Apr 16, 2021 | 08:41 PM

gblinkey

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A/C air flow / cold intermittent

I have a 2000 7.3.with a new vacuum pump.

A/C blows cold and hard.

After driving on the interstate for and hour or so, the air flow diminishes and gets warm. The air flow is not being sent to the defrost as the default.

Get off interstate and drive slower and all returns to normal.... cold and blowing hard...

any thoughts????

thanks

Apr 17, 2021 | 09:50 AM

alloro

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From: 0,0,1

Quote:

Originally Posted by gblinkey

Get off interstate and drive slower and all returns to normal.... cold and blowing hard...

any thoughts?

Any chance the belt is stretched, worn, or slipping?

Apr 17, 2021 | 08:35 PM

01__Excursion

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From: Rock Hill, SC

Belt or clutch gap may be a factor in the warming part, but the diminished air flow is probably a different issue.
If it's originally blowing hard, than your fan must be set on high ? If so and the air fades away from the dash vents, are you still hearing the fan on high? Their are only 3 locations for the air flow to go. Defrost, dash, and floor.

Apr 18, 2021 | 07:17 AM

gblinkey

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Thanks for the response.
I believe the warming is just coming from the lack of airflow. As far as I know and can tell the fan is still blowing on high.It’s just hard to tell, while driving by yourself ,where the actual airflow went to. I’ll have to do a little better job at diagnosing it when the Airflow disappears the next time.
Thanks again

Apr 18, 2021 | 07:24 AM

ToolmakerRob

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My brother's CCSB F250 had the same issue and we solved it after looking at the gap between the clutch and the AC compressor. We removed one shim, checked the gap and all was well after, good cold AC.

Rob

Apr 18, 2021 | 07:33 AM

projectSHO89

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From: St Louis

The clutch gap cannot cause diminished airflow, only loss of A/C cooling function.

Sounds like the evaporator is icing up.

Apr 18, 2021 | 07:41 AM

01__Excursion

Cargo Master

Joined: Nov 2017

Posts: 3,096

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From: Rock Hill, SC

^^^, I was heading in that direction...

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Apr 19, 2021 | 11:23 AM

projectSHO89

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From: St Louis

Quote:

Originally Posted by gblinkey

What would be the cause of the evaporator to be freezing up?

The evaporator is too cold and the air passing through it is too humid.

I could be that the refrigerant charge is wrong or the compressor clutch isn't cycling when it's supposed to. On a 2000, it''s likely a cycling switch that has stuck in the closed position.

Last edited by projectSHO89; Apr 19, 2021 at 11:50 AM.