thermo switch

hi guys
can you advise how i check the thermo switch, i put a multimeter on it open circuit
put in boiling water open circuit, i assumed it would close in boiling water to bring the fan on, any help appreciated
regards
chris

 

It's probably knackered. Our thermoswitches are just as unreliable as the voltage regulators, and are the usual suspects when fan doesn't come on when needed.

Best to leave it in place and wire a manual switch to activate fan, and that can result in better control of engine cooling.

 

ok thanks
but is there a way of actually testing the operation, what temperature
does does it switch?
cheers
chris

 

Boiling water should do. Specs are 98~102 Celsius.

 

auto parts store sells new ones every day

take part with you look up the same year ... but in honda/toyota car .

 

unplug the thermo switch, with key on touch the tab to ground with a jumper , if it doesnt run its bad , replace it , u can still get it from honda for 30 bucks

 

Wow, I just priced this from Honda. Retail: $84.49, and Service Honda: $67.43! I'll try Big3's alternative if I need to replace.
My fan comes on, but not until the temp gauge is almost pinned. Is this a bad switch, or should I look elsewhere? It never really overheats in traffic, but I think it's definitely boiling some coolant.
Thanks!

 

Here's some info I have.

Fanstat

Auto Tune PT2628
ACDelco E-1858
Beck/Arnley WorldParts 201-0817
201-1369
BWD (Borg-Warner) TFS500
Echlin (NAPA) FS-130
Facet FS8404
Filko TFS-1
Four Seasons 35934
G.P. (Sorenson) 40-5001
Kem TW-65
Mitech TS-84
Motorcraft no interchange
Niehoff WA-639B
Standard TS-84
Wells SW-504

Note: The following switches have a lower temp range than OEM Honda. OEM Temp Range: Closed Switch Temp Range=98c to 102c, Open Switch Temp Range=93c to 97c.

All are m16 X 1.5, N.O., 4mm Male Bayonet Connection, Closed Switch Temp Range=88.5c to 91.5c . Open Switch Temp Range=82c to 88c.

Beck Arnley 201-0817 ($20.00 Rockauto.com, Also Gates T274 $16)

Borg Warner TFS500

Echlin FS-130 (36.77 Napa)

Wells SW504

Niehof WA-639B

Four Seasons 35934

The above mentioned Thermo Switches should fit all models from 1975 thru 1987. A word of caution......I do not recommend running the OEM thermostat with these Thermo Switches. Your fan will be running all the time. I use the Stant 13868 82 deg C.

Note: The following switches have a lower temp range than OEM Honda. OEM Temp Range: Closed Switch Temp Range=98c to 102c, Open Switch Temp Range=93c to 97c.

All are m16 X 1.5, N.O., 4mm Male Bayonet Connection, Closed Switch Temp Range=88.5c to 91.5c . Open Switch Temp Range=82c to 88c.

Beck Arnley 201-0817 ($20.00 Rockauto.com, Also Gates T274 $16)

Borg Warner TFS500

Echlin FS-130 (36.77 Napa)

Wells SW504

Niehof WA-639B

Four Seasons 35934

 

Switch works, but...?

Thanks for all the great info. I disconnected the switch and jumpered the fan wires. The fan comes on when the ignition is turned on. All that tells me is that the fan and switch work, right? My question is: could the sensor have just gone out of calibration, causing it to turn the fan on above the temp when it should? I don't mind replacing it, would just like to know I'm going in the right direction, thanks.

 

If you ground the sensor wire and the fan comes on the circut is good. I forget about the grounding to radiator but it needs a good ground so when the thermo switch closes it grounds the circut, you could just run a temporary ground to the rad to see if it fixes the problem, if not the thermo sensor is bad (a common problem in bikes/cars) .
My fan comes on at the 3/4 mark, that's hotter than I like (not fond of replacing stators and cooking everything) so I wired a switch, if I'm going to sit in traffic I flip it on and the gauge never goes past half, only a issue in summer here.

 

I drained the radiator, removed the switch and suspended it in a pan of 50/50 coolant on the stove (I'm a bachelor, I can get away with ***t like that). Heated it to 220°F, or 104.4°C, and the circuit still didn't open. I conclude from that the sensor isn't opening when it should. Unfortunately, a trip to Autozone didn't come up with any useable matches from Captb's list above, which leaves me with 2 options: spring for the Honda part or follow Captb's other suggestion, to wire up a manual switch. Think I'll do that. Thanks for all the helpful posts!

 

might try a real parts store.

any mom & pop style auto parts stores near you? they are more inclined to open a book & look it up.

autozone, advance,pepboys sucks at stuff like that if it's not in the comp they dont have it mentaility.

 

NAPA will probably have one or keep an eye on Ebay for a deal. Good luck!

 

fan switch

Issue resolved, I mounted a toggle switch on the front side of the fuse holder, wired to the fan wires.[/IMG]
Thanks again for all the helpful posts. Great group!

 

Cyclepartswarehouse.com has the thermostat assembly for $25.34 and the thermoswitch assembly for $37.01 plus shipping if you want to keep it bone stock.
The best way is like the guys mentioned in here, wire up a switch and control it manually.

My nice 750 runs to 3/4 hot which I don't like so I'll probably have to switch out the thermostat and throw a switch on it also. My other 750 I have to plug/unplug it to power on the fan (haven't put on the switch yet) runs to about the middle when it gets hot.

 

If you run your own toggle, just be sure to do it in parallel so that at least it will still come on, albeit kinda late, if you forget.