Radiator fans issue

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Jul 8, 2025 | 10:42 AM

unibody62

Thread Starter

Laughing Gas

Joined: May 2002

Posts: 873

Likes: 37

From: Ohio

Radiator fans issue

While I was charging my AC, I noticed that electric fans started cycling to high speed, and then back to regular speed. Now, as soon as I start the truck, the fan goes on high, even though the truck hasn’t been running and is not heated up. The temperature gauge is normal, so I don’t know what’s going on. Any ideas anyone thanks in advance

Jul 9, 2025 | 11:58 AM

wulleebullee

Mountain Pass

Joined: Feb 2010

Posts: 101

Likes: 14

From: Diboll, Texas

High fans

Radiator fans immediately going on high in hot or cold temperatures, whether at operating temperature or not, can be caused by TXV, the expansion valve. This is a common issue in this series. It was the cause of mine.

Jul 9, 2025 | 01:47 PM

unibody62

Thread Starter

Laughing Gas

Joined: May 2002

Posts: 873

Likes: 37

From: Ohio

Quote:

Originally Posted by wulleebullee

Expansion valve in the A/C unit. I’m not real surprised, because the A/C acts like my ‘69 Tbird and it has a known bad expansion valve. I noticed that if I turn the air off, the fan settles down. I’m traveling 350 miles from home now, so it’s not a great time for faulty A/C. Good thing my wife isn’t along, she’d be miserable.

Jul 12, 2025 | 07:57 AM

projectSHO89

Hotshot

Joined: Jan 2004

Posts: 19,762

Likes: 1,079

From: St Louis

The computer controls the fan speed based on its inputs and programming.

Guessing as to the cause is usually unproductive. Looking at the underlying data usually is.

Jul 12, 2025 | 08:39 AM

HomerWinzlow

Logistics Pro

Joined: Jul 2003

Posts: 3,595

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From: Lawton, Oklahoma

Overcharging the system can cause instant high pressure which will cause the fans to hit high speed to keep the system pressures from blowing up your compressor.

Jul 13, 2025 | 12:15 AM

unibody62

Thread Starter

Laughing Gas

Joined: May 2002

Posts: 873

Likes: 37

From: Ohio

Quote:

Originally Posted by HomerWinzlow

Overcharging the system can cause instant high pressure which will cause the fans to hit high speed to keep the system pressures from blowing up your compressor.

I wondered about that also, simply because after I added part of a can that I already had, it still seemed a little bit low. That can had a dial type gauge on it. The next can that I bought had a digital gauge, but it still showed not fully charged when I first put it on. But after I did a couple of cycles of 15 seconds each.(per the instructions on a can.) it suddenly shot up to overcharged, but the fan started running fast even before that. I’ll recheck the pressure when I get home and if it’s over, I’ll try to let some out.