I am wondering if a fan going bad/out would/could cause its relay to fail. Is that normal and I don't know about it?

I run a dual Contour fan, each motor with its own 30--40 amp relay, triggered by a thermal switch. I keep blowing relays on one side. When I give that side fan power it works. Change the relay and it goes out in days.

Interesting.

 

Are you sure the fan's load is applied to the correct relay terminals?
Terminal #30 is wired to the battery and the fan motor connected to Terminal #87.....#86 is the signal hot. The temp sensor should be providing its ground signal through Terminal #85.

It could also be that the relay is undersized or not functioning up to the spec'ed amperage rating due to age or poor quality.

 

Hello, Hi-o, thx for replying. Yes, it all checks out. It's been running well for over two years. The only diff is that my relays show 87 and 87a. 87a is the hot signal. Fan is wired to 87.

Can a faulty fan case a relay to go out? I'm heading over to test it all now. thx.

 

Ah.. well OK.

The interesting thing about 'trons and 'trics is that resistance (heat) builds up as circuits age. In essence they become less efficient but draw more current. It could be that one of the electric motors is going bad and the indication is a burned up relay.... Consider switching to a different brand of relay. That'd be more better as a first step than changing out the fan(s).

 

Well, I found the hitch. I run a Taurus 30-40 amp relay to power each of my dual fans. I wired them separately so if one relay fails half the system will work. (Interestingly, I found that during the hottest days of summer, with temps near 100*, one fan will do the job.) One of the relay seats has a faulty/loose connector for the fan out power. I have to remove the lock insert that holds all the wires/female connectors in place from the bottom and secure the female connector so the male prong from the relay locks into it. Doesn't take long. It just takes some careful work, but enjoyable.

I'm amazed by what a person can find when they go digging through the forums for info. I found a thread where the guy swore that the black wire from the fan was hot, not ground. I wired it the way Ford did. It was easy to understand. Ford routed low thru a resistor.

 

'Glad you found the problem. I can't tell you how many times as a USN avionics tech I found pushed pins in connectors.

The corrective action was coded on the Visual Information Display System - Maintenance Action Form (VIDS-MAF) as 11-1A-799, or phonetically "Eleven, One-Alpha, Seven Ninety Nine" (intermittent contact).

One time a pilot spilled his can of Coca-Cola into the keyboard and track ball of his weapons station... dork!