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Relays...

AzPete

AzPete

Well-Known Member
The new electric fan stopped running on the way across town the other day. Messed with the relay and it started and stopped randomly. Got the car home ok and checked the relay again. It was real hot to the touch. Pulled it from the socket and the power out pin to the fan showed evidence of meltdown.

Relay has Painless stamped on the side and has a rating of 12 VDC and 2 X 20 Amp. It is of the 5 pin standard layout type with 2 power out pins. Now, I figure since the fan only uses one output pin, the relay should be ok for a 30 amp load. Looking inside and there is only one power out contact for the pins as normal. It shows signs of overload. Tested things again and the relay still got extremely hot so I replaced it with a new unit with one output and rated at 40 amps. New relay has not had a melt down with a couple trips across town in the last couple days nor does it feel to hot.

I have to assume, since I have no way of knowing, that this is the original system supplied to johnpro when he installed the elec. fan. Maybe age, maybe a bad relay, maybe a poor design. I could not find that relay on any painless sites either.

Just a heads up for anyone running these fans to keep an eye on that relay. For $6, it might be worth carrying a spare.
 
Hard to say Pete without reading technical specs for that specific relay. Maybe the input was only rated at 20-A. If so, your 30-A OCPD would have let it get too hot and not protected it. Did the relay run a 2-speed motor by chance? Maybe it just switched between 1 of the 2 outputs? high/low type of thing. If so - to me, that would say the input would have been just 20-A.

But I am also just swinging from left field here too.
 
The schematic drawing on the case plus a meter check shows it as two output pins wired as one inside. All that allows is to have two items plugged into it that operate at the same time. The 2 X 20 amp on the schematic seems to me to indicate a 40 amp load capability but like you....kind of baffled by it.
 
I don't know what fan you are running but the stuff I've been exposed to for years has been wired for 30 amps
 
Mine is the SPAL 2360 cfm straight blade. It is 30 amp so now I have a rated 40 amp with no question as to the rating. I also find it odd that I could not find the one that was in it from painless. Might call them for the heck of it.
 
"AzPete" said:
Mine is the SPAL 2360 cfm straight blade. It is 30 amp so now I have a rated 40 amp with no question as to the rating. I also find it odd that I could not find the one that was in it from painless. Might call them for the heck of it.
Click to expand...

You might check the wire gauge and make sure it is rated for 30 amp or you may just find the next weak link.
 
Talked to both Painless and SPAL concerning this little situation. Painless says the relay is rated at 40 amps, just capable of two 20 amp connections. SPAL says they have never seen that before and Painless is crazy. Either way, I have a good relay on there now. Wiring is good for the new fan too. It all checks out good on the car, grounds and all.

Some info I found out is interesting. The new fan is rated at 40 amps where the previous one I removed was rated at 30 amps. Minor change I was not told about when replacing.

Also, from the SPAL tech guy, this fan, part # 30102120 is the 2360 CFM straight bladed one, has a start up power surge of less that 20 milli sec in time but pulls 88 amps....yes, 88 amps. At the 200 milli sec time frame after initial startup, the power draw is at 56 amps. After that, it drops below 40 amps to about a 8 amp draw for constant running. The constant is based on different atmospheres also.

When he said 88 amps, he also stated that the time frame is so short that the relay and fuse does not notice that surge. A 40 amp fuse is all that is needed also. Mine has 30 amp circuit breaker....that will also get changed.

We also discussed the possibility of the old fan drawing a bit to much power being so old and causing the relay to start some melting. The circuit breaker should have functioned so not sure about that...either way.
 
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