Nobody responded to my earlier posts on these issues, so I will assume that none of the readers knows much about thermosensors and fan relays (or else they're a bunch of jerks for not sharing). My fan is now working properly, which tells me that my analysis of required specs was correct. Here is what I found: My fan wasn't coming on, so I replaced the thermosensor. I tested the old thermosensor resistance when cold (2,500 ohms) and hot (250 ohms), but never tested the new thermosensor. I tested my fan relay by placing an adjustable resistor (pot) in series with it and a 12.63 volt battery. I found that the relay wouldn't trip until the resistor was 55 ohms or less, corresponding to 230 mA or more of current. Since the old thermosensor never got that low in resistance, that might explain why the fan didn't come on. Maybe somebody will benefit from this data.

 

What are resistances?

 

A resistance is the ratio of voltage to current, which is to say that an element (such as a resistor) will only pass so much current with a given battery voltage. The unit of measurement for resistance is ohms. You can measure the resistance of an element by using a DVM, or digital voltmeter. This is such a handy, and inexpensive, piece of test equipment that it is a must. You can get a cheap one for $10, or a good one for $40 or more. The cheap one is good enough for most needs. It has two wires that you hook up to the element to be tested. To test the thermosensor, I hooked up the two wires to the two plugs of the thermosensor and dipped the thermosensor into boiling water. You can watch the resistance drop from 2500 ohms when cold to a very low resistance when hot. I don't know what the low resistance should be, but it probably needs to be less than 50 ohms. My bad thermosensor would only go down to 250 ohms, so it wouldn't pass enough current to trip the fan relay. A relay is a current activated device which operates by generating a magnetic field (due to current) that pulls on a piece of ferrous material to close a switch.

 

Isn't it DVOM? Digital Volt Ohm Meter.

 

What is your purpose here ? You seem to know nothing about the matter, and yet you are trying to correct me. Take some time to read about this stuff online. I tried to spoonfeed you and you bit my hand.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by The_Undertaker &raquo;</TD></TR><TR><TD CLASS="quote">What are resistances?</TD></TR></TABLE><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by The_Undertaker &raquo;</TD></TR><TR><TD CLASS="quote">Isn't it DVOM? Digital Volt Ohm Meter.</TD></TR></TABLE>

why is it that every other topic i look at you are posting irrelivant, offtopic, nonsence contributing nothing. please contribute if you can, if not dont post. people are here to learn, so dont spread missinformation. which is what i suggest you do, learn(read more post less).
hey, I'm not going to pretend I know everything. i'm not trying to insult you. i just want to point out that you seem to be taking on subjects you dont grasp, and then giving your advice on it.

please keep quiet