No AC and Fan Acting weird

[slonison]

Hey guys, need some help with my cars AC. A few months ago, I realized that when the A/C is turned on the, the fan will kick on but only run for about 3 seconds and then shut off. Then 30 seconds later, it will try again. This will go on indefinitely while until I turn off the car or turn off the A/C.

I only noticed because I was driving and would notice my RPM drop to about 600 and the voltage drop to 12. It would return back to 800 and 14+ but when I was driving, every thirty seconds was concerning.

I have replaced the alternator thinking it was that. No improvement.

I have noticed that when the cylinder head temp reaches 230*, the fan will turn on AND stay on. Until the cylinder heads drop back below about 226*

I read about the fan resistor and the fan plug. I checked my plug and there was absolutely NO issue with the plug, no burn marks, no damage to the connector. It looks basically flawless. I haven't checked the relays yet, but I'm not sure those are damaged either.

Any thoughts? Do you know how I can check my A/C refrigerant or my A/C compressor to see if they are still good?

 

[StockishS197]

Hey guys, need some help with my cars AC. A few months ago, I realized that when the A/C is turned on the, the fan will kick on but only run for about 3 seconds and then shut off. Then 30 seconds later, it will try again. This will go on indefinitely while until I turn off the car or turn off the A/C.

I only noticed because I was driving and would notice my RPM drop to about 600 and the voltage drop to 12. It would return back to 800 and 14+ but when I was driving, every thirty seconds was concerning.

I have replaced the alternator thinking it was that. No improvement.

I have noticed that when the cylinder head temp reaches 230*, the fan will turn on AND stay on. Until the cylinder heads drop back below about 226*

I read about the fan resistor and the fan plug. I checked my plug and there was absolutely NO issue with the plug, no burn marks, no damage to the connector. It looks basically flawless. I haven't checked the relays yet, but I'm not sure those are damaged either.

Any thoughts? Do you know how I can check my A/C refrigerant or my A/C compressor to see if they are still good?

On my 2006, my fan resister was fine but my BECs relay slots were melted completely causing intermittent high speed fan, which is usually called during AC.

I would pull the relays and inspect the pins. If it’s melted, you will need to bypass the BEC and replace your fan.

On my 2007, I proactively installed WireEverythings fan relay relocation harness and it works perfectly and is a plug and play install.

 

[08TorchRedShelbyGT500]

AS mentioned by StockishS197, there can be relay issues, wiring issues, and fan issues.

1. The fact that it appears your high-speed fan comes on when your CHT hits 230 tells me your low-speed fan isn't working at all. You should not be seeing CHT that high. You should rarely even need a high-speed fan, since the low-speed fan and its preset on/off temps take care of that. When was the last time you replaced your cooling fan assembly?
Once the fan assembly begins to fail, it "Tries" to run like it used to but draws much more current to operate, overheating relays and possibly some wiring, and if it gets hot enough, it shuts off or outright quits. This would also explain the voltage issues with charging. If a component is failing and drawing so much current to operate, your alternator won't keep up, and that would show the drops you are getting. You are overloading your charging system due to a simple fan assembly replacement.
The first step is to ensure nothing is melted or burnt. If you're lucky in that regard, check/replace the low and high-speed fan relays. Then you really need to replace that old fan assembly. A few of these troubleshooting items will get you narrowed down, if not completely fix your issue, but when you let a car go a long time without proper maintenance, the issue can manifest.

Also, to prevent any issue in the future, as StockishS197 stated, you need to look into the fix to prevent future issues. That is where the:
Dual Relay Harness Upgrade





Better Reading:

https://www.s197forum.com/threads/low-speed-cooling-fan-relay.154832/#post-2593521

 

[StockishS197]

One of the biggest design oversights of the these cars is the fan relay design.

If the high speed relay fails, low speed won’t run at all unless the PCM calls for low speed fan. So if your low speed system is fine, it still won’t run as a backup. This is exactly what happened with my 06.

AC often calls high speed fan, even if CHT/ECT isn’t needing it directly.

 

[slonison]

Ok,

A lot of this has been very educational for me. I had no idea replacing the fan assembly was considered preventative maintenance. I checked the plug on the fan assembly and it didn't have the burn marks. I will check the relays tonight.

I looked into the wire everything harness. I am very familiar with the electronics and design elements and will be making the harness myself. It's just not worth $199.

But before I do anything I am replacing the coolant reservoir. Evidently mine has a stress crack.

I'll be ordering the fan tonight. And checking out the relays. I'm hoping my A/C compressor hasn't gone the way of the dodo. Could this fan issue be resulting in no AC?

 

[StockishS197]

Ok,

A lot of this has been very educational for me. I had no idea replacing the fan assembly was considered preventative maintenance. I checked the plug on the fan assembly and it didn't have the burn marks. I will check the relays tonight.

I looked into the wire everything harness. I am very familiar with the electronics and design elements and will be making the harness myself. It's just not worth $199.

But before I do anything I am replacing the coolant reservoir. Evidently mine has a stress crack.

I'll be ordering the fan tonight. And checking out the relays. I'm hoping my A/C compressor hasn't gone the way of the dodo. Could this fan issue be resulting in no AC?

View attachment 116868

If the fan isn’t on when the AC is commanded on, it’s the fan or relays/wiring.

I would put AC on, see if the fan is running. The AC compressor should be easy to hear/see engaging to determine if that’s the issue

 

[slonison]

Here's 50 and 55. They appear to be fine.

When I turn the A/C on, the fan turns on for 3 second then turns off. It sits idle for 30 seconds. Then kicks back on for 3 seconds. And the cycle continues indefinitely.

I'm not sure what I'm looking for regarding the A/C compressor.

 

[MrBhp]

The part that melts is below what that relay plugs in to. The box separates into two pieces. That's where the damage is.

 

[MrBhp]

In your third picture you can see the prong has seen some heat.

 

[StockishS197]

The part that melts is below what that relay plugs in to. The box separates into two pieces. That's where the damage is.

+1. Though my 06s got hot enough to melt the relay AND the upper pins.

 

[slonison]

I gave it my best tonight. We'll find out in the morning if my best was enough.

 

[MrBhp]

Did you bust open the fuse box?