V8 VOL

Kind of feel like I am talking to myself, but I want to document this for anyone that may be searching on the topic.....

I installed the thermostat over the weekend (easy). I set the fans at 186 Low and 190 High. I also swapped the rear defroster relay with the high speed fan to eliminate that being the cause.

On cold start, the car works its way up to 186* and the fan kicks on. I drive it around for a little while to get some gas and the temps hang around 195, this is great news as it appears to be fixed.

Get gas, start the car, and drive off.......temps climb and climb and climb. I pull off once I saw 222*, no fan running.

I let the car cool down to below 186* to see if the fan will kick on. I start it and again at 186 the fan turns on, but the car is quickly overheating again, get home and the fan is not working.

My next step in this situation is to order a new fan. Lets just hope that is the problem!

Derf00

Look at replacing the cooling fan relay or coolant temp switch before the fan itself. The relay will be in the fuse box next to the battery.

It's rare that a fan works intermittently. An intermittent fan is usually a relay or temp sensor flaking out.

V8 VOL

So, this issue has shown up again. I had replaced the fan with an ebay fan. I think that information is relevant since that could possibly be the issue.....

The low fan comes on, but the high fan does not....sometimes. Sometimes its fine and it works how it supposed to. I guess you could call this an intermittant issue.

I have gone ahead and ordered a 2013 GT500 fan since its OEM and does provide with additional cooling.

Hoping this fixes the problem, but is there a chance there is something else going on?

All the relays and fuses look to be ok. I have not removed the fuse box to look for burn marks on the bottom, but will do that when I install the new fan.

edwin108

Since the fan seems to be working intermittently, you could also have a loose ground. According to the wiring diagram, the cooling fan grounds through G100:

wcgman

I would say you're looking in the wrong spots and going through a lot more time and money than you should be. How can you tell if a relay is bad by looking at it?

If I was having this problem, I would have replaced the relay first. Probably a lot faster, cheaper and less time to replace then waiting for parts to arrive.

V8 VOL

I will check the G100 ground when I get home. Thanks for that information!

How to tell if the relay is bad? Good question, perhaps you could help with answering that.....
Visually it looks good and when I was diagnosing the problem the first time I did put a voltmeter to it and everything checked out fine (with assistance from my Father-in-Law who knows his stuff when it comes to that type of thing).

Derf00

So you comment that you feel like you are talking to yourself, go out and buy a new fan even though It's already been mentioned that it's most likely NOT the fan. Problem persists. Surprise. Now you've ordered a second fan... What do you think will happen?

Relays and switches aren't like fuses where you can tell if they are fine by just looking at them. You have to test them.

An easy test is to swap the questionable relay with another on your car. Most relays are universal meaning they can be swapped with one from another area to test for functionality (if you don't know how to really test one). This isn't a definite test because the one you are swapping could be bad too...

If you don't have one to swap with or want to truly troubleshoot, these vids will show you how to do it.

(short version)
(long winded version but more educational)

Or, you can continue to throw parts at it and waste time and money...

If the relay checks out, then check your grounds, if the grounds check out, then check the cooling fan switch itself. If that checks out then you're on to more complicated stuff like wire tracing etc.

wcgman

I've seen a relay once where it was clearly bad. Major melt down, blackened like toast. But if there is no visual issues, you gotta check it with a 12volt source and voltmeter. Derf found a couple of great videos that explain how to test a relay. The second one is really good because he show you the inside of the relay so you can see what's actually happening. Or if you have access to a relay from another car that does work, you can always swap. My wife doesnt know it, but that's what her car is for My guinea pig! lol Troubleshooting electrical is some of the most frustrating parts of working on a car but when you finally nail it down, it becomes very rewarding because you frequently learned something new along the way.

wcgman

One more thing to add too...my 97 was having overheating problems. I was told the same stuff we all are telling you...the fans, the tstat, water pump, electrical.... turned out it was a plugged radiator. I might have been able to get it cleaned out, but it was just quicker and easier to buy a new radiator. Once it was replaced, never had an overheating problem ever again.

V8 VOL

This weekend when I dive into this project I will take note and check everything mentioned in the last few posts. I appreciate the videos and the feedback. Hopefully I can get this nailed down and find out the exact cause of my issues this time.

I did check the G100 ground last night and it was tight.