Strange Phenomenon with a strong tail wind at idle

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109
Location
Arizona
While waiting in a vehicle line idling for about 45 minutes (for the city dump) car started running hot, 230 degrees, AC working poorly, barely cooling the air. I turned off ac. Slowly cooled back to normal 210. New cooling system, always runs 210 no matter what. AC can freeze a side of beef (Except today) While waiting in line there was a tail wind about 30-35 mph. Ambient temps were 90 degrees, but my mirror indicated ambient temps at 116 degrees. Odd, as it is usually within 3 degrees even idling. As soon as I turned left into the dump (still in line) I had to roll up the windows as the dust/smell from the front loader moving garbage was awful. So I turned the AC back on and it worked perfect again, cold AC, normal temps. So do you think the tail wind was negating the airflow from the cooling fan causing these issues? Sounds like it to me. The wind was blowing directly behind me, and as soon as I turned perpendicular to the wind, vehicle was working like usual.
 
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Location
High Tax Illinois
Yep, You weren't moving so the fans were doing all the work, but a tail wind was evidently packing or distorting air movement in the engine compartment. My thoughts anyway.
 
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11,423
Location
Phoenix
On a day like today, you're really pushing the limits of the cooling system. A lack of airflow will really push them!
 

Nick1994

$50 Site Donor
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13,418
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Phoenix, AZ
Must have been early this morning, as it was almost 110 today. Check to make sure the electric fans are blowing good and hard, maybe they're weak.
 

Cmobile

Thread starter
Messages
109
Location
Arizona
I was in my Suburban, 5.3l, no e-fan, just mechanical. Was in Prescott. New AC delco OEM clutch fan, new bigger radiator. I thought my cooling system was good, just posted to see if it was a phenomenon, or an issue I needed to look at with my cooling system.
 
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Perris, CA
My XTerra would do this when I first bought it. Poor A/C performance at idle and would run hot with the A/C on and not moving. Issue was a bad fan clutch.
 
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11,423
Location
Phoenix
Originally Posted by Anduril
My XTerra would do this when I first bought it. Poor A/C performance at idle and would run hot with the A/C on and not moving. Issue was a bad fan clutch.
I think you're right.
 

MolaKule

Staff member
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Location
Iowegia - USA
Originally Posted by dishdude
Originally Posted by Anduril
My XTerra would do this when I first bought it. Poor A/C performance at idle and would run hot with the A/C on and not moving. Issue was a bad fan clutch.
I think you're right.
Me too! I had a Burb with a bad fan clutch. I went to the local GM dealer and bought a replacement. After installation the Burb would show high idling temps on a hot Kansas day. Pulled the fan and found the clutch had leaked its coupling fluid. GM dealer replaced with one that did not leak its fluid.
 
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ME
If your fan clutch were good you'd have hear the roar pulling out of the dump. Sounding like a school bus. If it didn't lock up then, when would it?
 
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16,259
Location
N.H, U.S.A.
Originally Posted by Cmobile
I was in my Suburban, 5.3l, no e-fan, just mechanical. Was in Prescott. New AC delco OEM clutch fan, new bigger radiator. I thought my cooling system was good, just posted to see if it was a phenomenon, or an issue I needed to look at with my cooling system.
Bad clutch fan. - or too low idle.
 

Cmobile

Thread starter
Messages
109
Location
Arizona
I'll check the OEM clutch for leaks. Been on about 6 months. I can hear the fan roar when it's hot above 1800 rpm or so. But not so much at idle. If I put in Nutral and rev to 1500-2000 rpms, it roars pretty loud. I do notice at idle, ac not as cold than when moving, but has always been able to keep up with heat load...except when idling with a tail wind. Scanner says idle 660-700 RPM. Always fluctuating. Lonf term fuel trim at idle a bit high at +13. When I was perpendicular to the wind, ac was cold and engine temps normal. Wind blowing 35mph to the North, Engine fan blowing air to the South. Does this create static pressure? Fan air blowing over the radiator has a harder time exiting the engine compartment due to the wind blowing the opposite direction. Only time this happened was during this unique situation. Like the train going 60mph East, wind blowing 60mph East, which way does the smoke go... Save for the electric train part...
 
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