electric fan woes, or "if it aint broke, don't fix it" - Team Camaro Tech
Electrical & Wiring Troubleshooting electrical.

 
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post #1 of 8 (permalink) Old Jul 10th, 03, 08:35 PM Thread Starter
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Sean
 
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well this is my story. sorry its so long. i've been running an elect. fan from a v-8 cad on my camaro for about 2 years now. it cools good, and has worked well. problem was, i had a cheap mechanical t-stat that would run forever, and was just real inaccurate i felt. plus i never wired in an off switch, so it ran auto all the time. that was not a problem, but i wanted to shut it off before i made a pass, and couldn't. so, i decided to go with one of derales solid state fan switch/relay packages, liked the nice neat install it would provide. wired it all in, made it look all nice and pretty, but the thing so far works like crap. when setting the t stat i noticed if i just turned the adjustable pot it would come right on, and turn it the other way, it would turn right off. so far so good. but when just allowing it to turn on at the pre set temp by itself, the relay contacts would chatter like a mofo, but eventually pull in. sure it works, but i'm thinkin i'll need a box of relays everywhere i go, cause this going to trash them. so i call derale, and i actually get real decent tech support, and the guy figures, as did i, the relay must be bad, so he sends one out to me, no problem. he did show some concern about the fan i was using, since the unit/relay are only good for 30a. but i have been runing this fan for years now, with a 25a fuse, and never an issue. he said i may still need a larger relay, and to use the derale unit as a trigger. i'm thinking i could have just assembled my own set up with a t stat if thats the case, cause now we're talking so much for the "clean package, easy install". well i couldn't wait, so i went and got another 30a relay from the parts store, tried it, and same thing [img]graemlins/angry.gif[/img] . so i'm not sure what the best solution is now, just find a bigger relay and use the derale to trigger it, or just start over, that seems like the easiest clean solution at this point. i don't think its the relay myself, because it holds fine when switched manually. i'm thinking some problem with the internals on the switching. anyone dealt with the derale fan switches? also, if your reading this chicane, you had a link to a wiring diagram for the lincoln fan set up, but i couldn't find it, if you could put up a link to it, i'd appreciate it. i'm thinking about just doing it that way now. this is pi$$ing me off, i'm a freakin' electrician, i have set up auto start stops with plc's and vfd drives on 1000 horse motors, but this stinkin' little fan is kicking my ***! any input would be greatly appreciated, thanks [img]graemlins/beers.gif[/img]

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #2 of 8 (permalink) Old Jul 11th, 03, 12:49 AM
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So far I like my painless kit. It comes with a relay (I used 2 for my dual fans) a thermostat that screws into the water neck. It comes on at 200, and off at 185... You can easily wire a switch to turn the fans off. Not sure if that helps any, but my setup works pretty good.
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post #3 of 8 (permalink) Old Jul 11th, 03, 05:25 AM
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Your temperature switches dead band is to small, or the switch is bad. Dead band is the difference between when the contact opens and closes. Don't know if yours is adjustable or not, as I'm not familiar with the system your using. The switch should have at least a 5 degree, and preferably 10 to 15 degrees of dead band. If the fan is supposed to come on at 195F, it should not turn off until the temperature gets down to 185F, or 180F. If the dead band is to small, say a degree or two the contacts will do exactly what you are describing, chatter back and forth, picking up and dropping out the relay.

Mark Canning
1969 Indy Pace Car
350/300HP RPO Z11

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post #4 of 8 (permalink) Old Jul 11th, 03, 11:30 AM Thread Starter
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mark, yeah, thats kind of what i was thinking as well. like the dead band is too tight or non existant, or it's switching has got issues because like you said, it comes on but it chatters bad, like its half way between coming on and going off. i don't know if your familiar with large electric motor starters, but it sounds like a starter that has the wrong voltage coil or not enough voltage to hold the coil. but i know my voltage is good. unfortunately its completely sealed and unadjustable, except for the temp. adjustment. thats another reason i don't like it now, you simply cannot trouble shoot the stupid thing except for knowing if it's wired right and the voltage is good or not. thats why i liked it at first, neat and tidy package. but now that it's not working right, neat and tidy isn't such a good thing maybe i will take it back and try another one, like you say, this one very well could be bad from the factory. and spames, at this point, i wish i had gone with the painless set-up, if i can't get this one dialed in, i'm going to do that or just put together my own, at least then i can trouble shoot it. thanks for the input guys, i'll let you know what i end up with [img]graemlins/thumbsup.gif[/img]

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #5 of 8 (permalink) Old Jul 11th, 03, 01:21 PM
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Nuclear Power Plant Electrical and Instrumentation engineer. I've engineered and installed everything from 30,000A, 22KV breakers to 4-20ma level transmitters and limit switches. I like the low voltage stuff better though.

Mark Canning
1969 Indy Pace Car
350/300HP RPO Z11

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post #6 of 8 (permalink) Old Jul 11th, 03, 11:11 PM Thread Starter
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cool deal, that sounds like really interesting work. the bulk of large motors and plc's i've dealt with were at the paper mill in town, there are more different types and sizes of motors there than you can shake a stick at, and since its been running since the early 1900's, they are running stuff with state of the art plc's, on down to switchgear that still uses tubes, and even a couple of motors still in use for power factor correction. it's quite a site to see. lots of my 4/20 ma instrumentation exp. has been at the local refineries, cool equipment to wire, not such a cool place to work, it stinks 24/7. and our local airplane factory, boeing is pretty interesting as well. we have some nuke plants, but they don't have a lot of action lately, and i havn't worked at one yet, but would like too. and we have some hydroelectric as well. i love the field i'm in, it's always interesting, as i'm sure you well know. oh, as for the fan situation, i went and exchanged the whole unit to see if that was the issue, and it still chattered bad. so i just put together my own set up using a 30a relay, and my old mechanical t-stat, and it works just fine now. i changed the location of the probe, and connected a sp/dt center off switch, so now i can use it in run/off/auto. it works great. thanks again for all the input! [img]graemlins/beers.gif[/img]

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #7 of 8 (permalink) Old Jul 14th, 03, 05:37 PM
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joseph l clance
 
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Hystersis: your fan control needs at least 15* of it to operate properly. The relay does not appear to be your problem.

69 X-44 base coupe, ZZ4, 16lb nodular flywheel, Center force DF clutch + PP, Holley 600DP, Hooker super comp 1 3/4 ceramics, 2.5" dual exhaust w/ X-pipe, flowmaster 40 series mufflers.
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post #8 of 8 (permalink) Old Jul 14th, 03, 09:33 PM Thread Starter
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joe, yes the relay was just fine, i figured my problem lay somewhere else. i think it was just the internal electronic controls of the "module" that they have (derale), just not switching properly, due to the load or some other internal issue that can't be trouble shot . thats why i 86'd the unit, and put together my own circuit, using the relay from the unit, my old mechanical t stat switch, and a spdt switch to make it all happen. it works good, although i feel my t stat still needs some dialing in to be right. could you explain to me what you mean about hysteresis, i'm not quite clear on the role it plays in this application. from the majority of stuff i do, hysteresis, i.e power loss through heat generated by molecular friction, similar to eddy losses and I2/R losses. which are bad things in motors and/or generators, and if excessive can damage them. this is my limited understanding of course. i'd be interested in what you mean, i find stuff like this pretty interesting. thanks for the input [img]graemlins/thumbsup.gif[/img]

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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