09 Yukon Intermittent fan e-fans not running

olliec420

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So the other day I went out and the a/c kept turning itself off. It was nice out so I put down the windows and was going to look at it later. Im about to get to the store sitting at a light and I notice the temp is over 210 (where it normally sits). I turned the heater on and when I started moving the temp went down. At this point I knew it was the fans. I stopped in the parking look and looked and sure enough no fans. Fuses ok. Headed to a friends with heat on and windows down. Looked at it for bit and shut it down. Hung out for a while, reseated the relays. Started it back up and they were working so I went home. Started it this morning and they weren't working so I headed to auto zone to get a relay (fan control relay). They started working on the way, I know this because the A/C came on and stayed on. Someone on reddit told me the system will shut down the a/c if the fans aren't turning when they should.

Thinking back, there was a time over the winter when it a/c wouldn't start and I wasn't really worried about it because it was super cold out so I had the heater on anyway. I didn't notice any rise in coolant temperature then. But this tells me it is an intermittent issue that started while ago and now is much more frequent.

Anyhow, today I got the relay and put it in and they didn't seem to start right away. We tapped on one and it started and then tapped on the other and it started. Could that be coincidence? I dont know. I tried that again and one started and one didn't. Is there a time delay before they come on when starting up, even when engine already hot? Could it not be the relay but the fan assembly itself? What are the chances of both fans crapping out at the same time? Oh yeah, 160k miles. I dont mine getting new fan assembly, I just need to be sure that is going to be the fix. Anyone had this problem?
 

Doubeleive

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So the other day I went out and the a/c kept turning itself off. It was nice out so I put down the windows and was going to look at it later. Im about to get to the store sitting at a light and I notice the temp is over 210 (where it normally sits). I turned the heater on and when I started moving the temp went down. At this point I knew it was the fans. I stopped in the parking look and looked and sure enough no fans. Fuses ok. Headed to a friends with heat on and windows down. Looked at it for bit and shut it down. Hung out for a while, reseated the relays. Started it back up and they were working so I went home. Started it this morning and they weren't working so I headed to auto zone to get a relay (fan control relay). They started working on the way, I know this because the A/C came on and stayed on. Someone on reddit told me the system will shut down the a/c if the fans aren't turning when they should.

Thinking back, there was a time over the winter when it a/c wouldn't start and I wasn't really worried about it because it was super cold out so I had the heater on anyway. I didn't notice any rise in coolant temperature then. But this tells me it is an intermittent issue that started while ago and now is much more frequent.

Anyhow, today I got the relay and put it in and they didn't seem to start right away. We tapped on one and it started and then tapped on the other and it started. Could that be coincidence? I dont know. I tried that again and one started and one didn't. Is there a time delay before they come on when starting up, even when engine already hot? Could it not be the relay but the fan assembly itself? What are the chances of both fans crapping out at the same time? Oh yeah, 160k miles. I dont mine getting new fan assembly, I just need to be sure that is going to be the fix. Anyone had this problem?
I would be checking the temperature sensor/sending unit, a issue with the fans/relays being bad would be very rare. after the temp sensor the next suspect would be the pcm or pcm wire harness, water intrusion can cause corrosion and bad connections.
 
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olliec420

olliec420

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I would be checking the temperature sensor/sending unit, a issue with the fans/relays being bad would be very rare. after the temp sensor the next suspect would be the pcm or pcm wire harness, water intrusion can cause corrosion and bad connections.
From reading in another thread I understand that if they sensor wasn't working, it would be fans on full and a/c off. I got no fans and a/c off. Actually that may be a better title for this post.
 

Doubeleive

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I would hook a tech2 or other similar tool to it then and see what is going on, i.e. what is the temp it is reading and what being command or not commanded, etc.
check the pcm harness it's fairly common for things like this to be caused by poor connections
 
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olliec420

olliec420

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It has to be the fans, today again, they come on when I slap them. Several videos on YouTube about fans going out. Got upgrades ones coming from Summit. Will swap and report back.

Also while I was scanning it (I have iCarsoft i900 scanner) I noticed the ambient temp sensor was stuck 64.4 and it was well over 70 out. I don't know if its broke or needs calibrating some how. A new sensor is $8 so I'd assume replace it. No other codes or anomalies that I could detect.
 

swathdiver

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There are 3 relays for the fans. The fan motors are the 500 watt variety for an XFE. You need a Tech-2 to properly diagnose this.
 

Doubeleive

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It has to be the fans, today again, they come on when I slap them. Several videos on YouTube about fans going out. Got upgrades ones coming from Summit. Will swap and report back.

Also while I was scanning it (I have iCarsoft i900 scanner) I noticed the ambient temp sensor was stuck 64.4 and it was well over 70 out. I don't know if its broke or needs calibrating some how. A new sensor is $8 so I'd assume replace it. No other codes or anomalies that I could detect.
are the fans on there now original? or some aftermarket?
 
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olliec420

olliec420

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are the fans on there now original? or some aftermarket?
Originals. It’s definitely the fans. Both of them too. It can’t be coincidence at this point how many times they and the a/c don’t run unless I open the hood and physically smack them and they start and everything works. I don’t know when that ambient temp sensor quit but that’s getting replaced too considering the low cost of the part.
 

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Originals. It’s definitely the fans. Both of them too. It can’t be coincidence at this point how many times they and the a/c don’t run unless I open the hood and physically smack them and they start and everything works. I don’t know when that ambient temp sensor quit but that’s getting replaced too considering the low cost of the part.
hmm first I have heard of the oem fan motors failing, have you pulled the connectors off and inspected the wiring harness at the fans? there was a recall for the harness melting and potentially causing a fire hazard.
 

mattbta

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lsxmatt has a youtube about having to replace the fan motors after running his e-fan swap for some length of time. had oem fans that were of unknown usage and replaced with oem motors.
 

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