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Posted: 7/11/2010 6:21:37 PM EDT
I need a delay to shut off.

Basically I have a relay attached to a switch that turns off and on a little too fast for my taste. It causes an electric fan to cycle based on a/c high side pressures.
The fan barely gets up to speed and the pressure is down enough it causes the fan to turn off.

I want to put in some sort of delay that lets the fan run for a min or two before it shuts down. I can rewire if I have to, but figured if there was a plug and play replacement relay all the better.
Link Posted: 7/11/2010 6:26:07 PM EDT
First, look in the grainger catalog

After that, perhaps an old Bosch glow plug relay - folks used to rig them up as an after-run timer for VW turbo diesels.

Also, it sounds like you need to replace/adjust the pressure switches.  A time delay relay sounds more like a band aid.
Link Posted: 7/12/2010 6:12:29 AM EDT
For 12V?
DEI 528T Pulse timer relay will do what you want.
Link Posted: 7/12/2010 6:38:47 AM EDT
Thanks. Looks good. Too bad it isn't a direct plug in, but I will live.

No issue with the switch.
It is working as designed. The "problem" is the electric fan is just too powerful for what I am using it for. It takes several seconds to fully spin up, but that is a lot of air movment. And it is enough to bring the pressure down to the shut off point.

I don't know if it is bad for the fan or not, but I don't want to risk it. Plus it would only be a problem in stop and go driving, not moving. So a 90 second dely at a stop light should be plenty.
Worst case it cycles on a couple of times, vs the 5 to 10 times it normally would in that time frame.
Link Posted: 7/12/2010 6:49:18 AM EDT
Link Posted: 7/12/2010 8:30:22 AM EDT
Odd shapped, but it looks lit it will fit a standard plug too.
Link Posted: 7/21/2010 11:38:46 AM EDT
I think Dakota Digital sells a fan timer.
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