iMac high fan speeds, slow

[timeshifter]

Mother in law's 21.5" 2014 iMac having trouble. Recently they had lightning nearby. It took out their cable modem and router. Printer, computer, etc were apparently spared. The iMac was plugged in with Ethernet to the router.

The iMac still works. Ethernet port works. But something's not right. Soon after startup, before OS even loads all the way the fans will start whirring. Computer is extremely slow. It was slow before (has a regular hard drive) but not this slow.

I tried resetting SMC and PRAM more than once. Tried booting from an external SSD. The fans kick on when selecting the boot disk (holding down Option and clicking the volume to boot from)

I'm fairly sure I'm dealing with a hardware issue at this point. Bad logic board, bad temp sensor, bad hard drive overheating... listed as worst to best case scenarios.

Thoughts?

 

[Markverhyden]

I'm fairly certain that's one of many models that had HD temp sensors. Either attached or via HD logic board. I know smcfancontrol can handle fans, just don't remember if it displays temps. I know there's temp apps out there but have never looked at any. If the drive is ok then it's probably a logic board issue. Maybe one of those temp apps might point it out.

 

[timeshifter]

So if the computer thinks its too hot the fans will spin up, on an iMac is it also going to throttle the CPU? The computer is really slow. Even when booted from an external SSD.

 

[overburnz]

So if the computer thinks its too hot the fans will spin up, on an iMac is it also going to throttle the CPU? The computer is really slow. Even when booted from an external SSD.

send me the sn of the iMac i’m not sure if that model can run remote diagnostics but if so i can try to run some tests and check that out for you

 

[sapphirescales]

Download some software to control the fan speeds and check the temp sensors. See if you can manually control them. If you can't, then the controller is shot. One of the fans might have actually failed, or it could be a bad sensor.

 

[timeshifter]

Can't believe I never ran the built in diagnostics by pressing D on startup.

"There may be an issue with the System Management Controller (SMC)."
Reference Code: PFM006

 

[Markverhyden]

Can't believe I never ran the built in diagnostics by pressing D on startup.

"There may be an issue with the System Management Controller (SMC)."
Reference Code: PFM006

Wow!! I'm surprised. Most the time Apple Diag says there's no problem. LOL

 

[timeshifter]

So what do you guys think are my best options at this point?

• find a logic board on eBay and swap it myself
• send the board to Louis Rossman
• send the whole system to Louis Rossman
• something else

I do want to repair it, it's my in-laws. I wouldn't get involved if it was a paying customer.

 

[HCHTech]

Family stuff is hard, isn't it? My vote is they should be told something along the lines of "You got 6 good years out of this machine, while we might be able to fix it, it is certainly at the end of it's expected lifetime and you should consider a new machine."

I've found that the more you try to save them money by repairing something that shouldn't be repaired, the more trouble they & you will have, and they end up thinking you don't know what you are doing, or aren't good at what you do. I treat them like regular clients now, and my life has gotten just a bit easier.

 

[timeshifter]

Louis Rossmann not an option:

"We do not accept board-only repairs.

We only work on devices when the full machine is sent – we do not work on board only repairs where the logic board is sent by itself.

We do not work on iMacs over the mail.

We have told several people over the phone that they should not send us iMacs because of potential for shipping damage. Unfortunately, they send us iMacs anyway, and they wind up damaged in shipping. To be clear, we take no responsibility for shipping damage on iMacs since our site says that we will not work on them if mailed to us. Please do not mail us iMacs: bring them in person or find someplace local."

https://www.rossmanngroup.com/shipping/

 

[timeshifter]

New system ordered.

Anyone want to buy an as-is 2014 iMac?

 

[Markverhyden]

New system ordered.

Anyone want to buy an as-is 2014 iMac?

fleabay....

 

[OrCrush]

So what do you guys think are my best options at this point?

• find a logic board on eBay and swap it myself
• send the board to Louis Rossman
• send the whole system to Louis Rossman
• something else

I do want to repair it, it's my in-laws. I wouldn't get involved if it was a paying customer.

I've had this same problem on more than one iMac, and the solution was not the same on each of them. If it was just the fans, I'd suspect the hard drive temp sensor, however you also have slowdown which can also be an overheating CPU (self throttled to preserve itself), to a poorly reassembled machine after an amateur worked on it (leading to thermal issues and god knows what else).

Definitely run a full system diagnostic. If you don't have access to Apple's pro tools, at least run AHT. You can also use something like TechTool Pro's hardware checks, they're better than guessing.

Before replacing a motherboard, there are 3 key things I would check:
1) verify that the fans, ventilation channels and heat sinks are not clogged with fuzz/lint/dust/debris. They won't do any good if they are clogged up but the fans often can still spin like crazy. A 6 year old machine collects a lot of crud.
2) verify that the internal HDD has a temperature sensor, and if it's external to the drive that is properly connected and thermal paste intact. Same goes for the CPU heat sink. By the way, unless you completely disconnect the internal HDD, the system will still try to read it's temp and react accordingly even if you're booted from an external drive.
3) zap the PRAM and reset the SMC, I think someone else mentioned these, they often will chase out ghosts in the machine