Bear with me on this. I think I have narrowed down the problem to my thermostat and the thermo switch on the front of the engine (upper radiator hose) but would like confirmation if possible.

Neither one of the radiator fans would come on with the engine running and warmed up unless the A/C was turned on, then both would engage. Neither of the fans would come on after driving and then turning the engine off; as I recall, one of them used to come on if the engine was hot but shut off. I jumped the connector to the thermo switch on the thermostat housing and both fans would come on with the ignition on. I jumped the connector on the front thermo switch and the passenger side fan would come on with the ignition turned off. I removed the thermostat and did the hot water test and it opened, but I still suspect it because with the thermostat removed both fans will come on with the engine running and warmed up. I tested both thermo switches in hot water with a multi-meter and got continuity on the back one but not on the front one. All other fan power, ground, continuity and relay tests were good.

So, does it sound like the front thermo switch is bad? I should have seen continuity on my multi-meter at some point during the hot water test, correct?

 

94 and the fans work when you jump the connector at the t-stat. T stat's don't cost that much, replace it. If I read your post right, everything worked when it was removed.......Then,if still acting up, re-check/replace the switch (green)at the t-stat (lower hose).

The upper hose switch controls the fan (single) to run when the car is off.

 

Sorry, my post was a little confusing.
Yes, the thermostat will be replaced and everything works with it removed...except I'm not sure the switch in the upper radiator hose is functioning. I tried testing it in boiling water and monitoring the resistance between the terminals. Normally the resistance is infinite - open circuit. At some point (the temperature threshold of the switch) the resistance should drop to zero, closing the circuit and triggering the passenger side fan, but that never happened in my test. I thought maybe the switch temperature rating might be higher than the boiling water, which is roughly 212 degrees F. If that is the case, the switch may be good but I never got it hot enough for it to close.

I'm trying to figure out all the parts I will need so I can order them all at once.

 

Don't hold me to the exact temps. The "other" green switch on the "upper" hose is rated at around 225. So if the car is off, and it detects temps above that it will kick the one fan on.

So start with the t-stat. Then if the issues continue, look into the other.

 

The A switch (thermostat housing) is operational between 194°F and 205°F
The B switch (upper rad hose) is operational between 217°F and 228°F

 

Thanks! Sounds like the temp may not have gotten high enough for the switch to close. Looks like I'll just be replacing the thermostat first...

 

It's very easy for an air pocket to get stuck by the thermostat that won't let coolant get to the thermostat and/or switch. Make sure you open the bleeder bolt on the thermo housing before you start adding coolant.

 

Yeah, did that, too. The T-stat is out now so might as well put a new one in; the old one had been in there for at least 7 years.

Thing is, I don't think I will now know if the "B" thermo switch is good or not unless the engine overheats!

 

Thanks GhostAccord....I thought it was around there....my memory gets fuzzy every now and then

mherrcat..."B" is only when the car shuts down-heat soak. If the coolant gets to the temp range after the car is off then "B" kicks the one fan on. You can always pull it and test is to be sure.

 

Thanks. I replaced the t-stat today and things seem to be working fine; the fans come on intermittently after the t-stat has opened.

I did try to test the "B" switch by immersing the sensing element in boiling water and it didn't close, but I don't know how reliable that is if the switch closes between 217 and 228 degrees Farenheit. The boiling temp of water is 212 degrees at sea level and since I am at about 378 feet above it may even boil at less than 212 degrees, so the water may not have been hot enough to close the switch.

I tested the "A" switch the same way and it worked, but its threshold is lower than the boiling temp.

Good info though and thanks for the help!

 

If you really want to test it you could try using an old pot, or disposable tin cup, filled with 50/50 (coolant) and boil it. The boiling temp of 50/50 is in the 225°F range IIRC.

 

Now why didn't I think of that?

 

 

I've had a similar problem as described here. I'm about to replace the thermostat and would also like to replace the "A" switch and possibly the "B" switch. I read above they have different temp ranges...are they identical other than that? If so, my local parts store only has one model available. Where should I look to order and be sure I have the right one?

 

They are different. The "A" switch has a longer sensor element than the "B" switch. I would try testing the switches first before going to the expense of replacing them. There seem to be several places people order from that are popular; I usually order from this one:

http://www.hondaautomotiveparts.com/

However, the shipping and handling charges may make ordering a single part about the same as buying it from your local dealer; that's what I found in buying the thermostat, so you may want to compare prices before ordering online and having to wait several days to get your part.

I also noticed that the thermostat that came out of the car looked like a typical cheap aftermarket unit. The Honda t-stat I got from the dealer was more substantial and looked like a better part.

 

Thanks for the information.

 

speaking of the cooling system, i had totaled my accord and jus rebuilt it. but the wiring for the fans had gotten messed so im not sure which wire is what. and also would it be possible that the fan relay went bad when i wrecked it?
please need some help thats the only thing keeping me from gettin it back on the street. It a 94 ex

 

Which wires are you trying to figure out?

 

im tryin to figure out the wiring for the radiator fan. i changed it to a single aluminum radiator with a universal fan. i thought i had it right but once it got hot it didnt kick on.

 

Oh, well that would have helped to know in the begining.....

OE, there should be a BLU/BLK wire that supplies power to the Cooling fan....the other side is ground....sounds like you only have one fan now?

 

yea now i have an aluminum radiator that dosent go all the way across like the stock an just one fan. There is another set of wires not that far down from the blu/blk wire i think is orange or red. What are those for?

 

That could be to the ac compressor, does it come from the left/drivers side almost from under the headlight. There would have been two relays and wires there. Some of the wires and one relay ran the "condensor", some of the other wires and relay ran the compressor...

If this is coming from the right/pass side, need to know as it could be something else...like the reason you are running 3k rpm's at 60 mph

 

i know what the wires are on the driver side did a way with everything that had to do with the ac awhile ago, before i wreckked the car. The wires i was talking about is on the same harness for the fan wires.

 

Pic's? I'm getting lost here, of course it is late. Is there a BLU/BLK wire or not? Should see continuity from the cooling fan relay to where it "ends" somewhere under your hood.

 

Factory Service Manuals/wiring diagrams+ multi-meter=solutions