low relay resistance coil

Hi to all. I replace a AC compressor using a magnetic valve the resistance was 11 ohms now i need to use a relay to replace the valve I tried a bosh relay with 85 ohms but it will not activate the relay coil do you know of a relay with a resistance close to the magnetic valve or some thing I can used ??

What voltage & current rating for the contacts?
What coil voltage rating?

Thank for the quick reply.I Did not check voltage nor current but I believe it's 12 volts it's operating the compressor coil witch is 12 volt 4 ohms but is burning the compressor coil because current is to low.Do you know of any relay operating on 11 ohms??

Is the coil in series with something?

I don't understand the situation....
If the relay's coil load has to be something specific (but why?), then just add a parallel resistor (eg, say a 12 Ohm 20 W resistor for 12V).

And you can't use a relay to replace a magnetic valve. Do you mean replace a relay that controls the valve, and the valve has 11 Ohm resistance? (That's ~1A @ 12V (hence 12W) but most relays will handle that - eg, automotive Bosch-type 15A or 30A relays that have a typical coil resistance of 60 Ohms or more....    


But be sure of the voltage... if it's a 120V or 220V AC compressor/system/relay then using 12V stuff is DANGEROUS!

OK since you from Australia You know the 2005 Toyota hiace Lwb it has an electronic AC compressor with a magnetic valve now I have change it to an electrical compressor but relay will not work.

Nah - sorry, I only know of mechanical aircons with electric clutches driven off Vee or serpentine belts etc (and Peltier devices, but hopefully not for aircon!), and the various interlocks like idle cut-off (of the clutch) or fast-idle etc.

I'm not aware of valves per se - except for bypass (maybe during idle) or pressure relief etc.


Again, sorry.

I'll leave it to someone that understands....

Thank for the help maybe a Transistor will do the job. Do you know about transistors??

Yep. Not that I see how it helps.....
If you want switching - use a MOSFET.
If you want resistance, use a resistor.

wth is a magnetic valve? I've never seen one in an automobile AC. You won't find ANY automotive relay under 85 ohms coil resistance, the first poster is looking at another problem.
Florida? Every gas station has an AC expert, go to one.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Problem solve a resister across the relay coil was it

Another FIGJAM Howard? (I was expecting a WOMBAT or WOFTAM.)
Yet another example of a solution without the problem or situation being fully understood - or at all. (I should have said "repair"; those solutions are done all the time by management, and some Florida audio forums.)

So it is some system that senses load (coil) current, or feeds thru the coil, or is still totally misunderstood.
I'll bet it's a hot little resistor though....

Thank Old park. That was grate you solved my problem I put the resister across the relay coil and that was it.

Since I don't know maybe Oldspark or some other erudite chappie could explain the pros and cons of placing a resistor across the coil.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Old spark. The resister value you give me for the relay. Just what I wanted you are so correct.I like to have other choices with my project what value of transistor can I used

howie ll wrote:

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..maybe Oldspark or some other erudite chappie could explain the pros and cons of placing a resistor across the coil.

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It's like I alluded to in my 2nd reply... "If the relay's coil load has to be something specific... - somewhat like an alarm loop circuit.
It checks it isn't a short nor open, else checks for a specific impedance (which is only provided by their special Part No which is a rehoused $3 relay and $2 resistor selling for over $123), else has a recalcitrant impedance dependent driver....


However the OP's system is such a puzzle, any reality is likely.
And using a transistor? For what or why???

Thanks, Peter.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.