Car overheating, radiator fan only works when car is off??
 

A couple weeks ago my car started overheating if I was at a stoplight for too long, but it would be fine as long as I was moving. For the time being, I just turned the heat on high and it would be fine. But with the hot weather keeping the heat on is just unbearable.

The A/C condenser fan works fine, and the radiator fan works fine when the car is off. But when the car is turned on, it just stops working. What's the problem here? Thanks in advance.

Re: Car overheating, radiator fan only works when car is off?? (pyrojeff)
 

Did you check to see if there was any coolant in the radiator? Mine use to do that because I had a very small leak (steam) in my radiator and it ran low and the fan kicked on when I turned off the motor. I replaced the radiator and bled the system and no more problems.

Re: Car overheating, radiator fan only works when car is off?? (technine)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by technine &raquo;</TD></TR><TR><TD CLASS="quote">Did you check to see if there was any coolant in the radiator? Mine use to do that because I had a very small leak (steam) in my radiator and it ran low and the fan kicked on when I turned off the motor. I replaced the radiator and bled the system and no more problems.</TD></TR></TABLE>

Yes, coolant levels are fine.

Re: Car overheating, radiator fan only works when car is off?? (pyrojeff)
 

I guess check to see if the radiator fan relay is working correctly. I am not too knowledgeable about that though. Does it EVER overheat on the highway while driving or just in stop and go/city driving?

Re: Car overheating, radiator fan only works when car is off?? (technine)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by technine &raquo;</TD></TR><TR><TD CLASS="quote">I guess check to see if the radiator fan relay is working correctly. I am not too knowledgeable about that though. Does it EVER overheat on the highway while driving or just in stop and go/city driving?</TD></TR></TABLE>

Never on the highway, only when I'm sitting at a stoplight for an extended period of time. Once I start moving again it cools down pretty rapidly.

Re: Car overheating, radiator fan only works when car is off?? (pyrojeff)
 

I think in '94 there were 2 fan switches & a fan timer module. The fan switch on the thermostat housing is responsible for running the fan while the engine is on. Unplug that & jumper the wires with a paperclip or something. Key on, that should make the fans run.

If it does, you've just demonstrated that all the fuses & relays are working OK. So you need a new fan switch.

Re: Car overheating, radiator fan only works when car is off?? (JimBlake)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">I think in '94 there were 2 fan switches & a fan timer module. The fan switch on the thermostat housing is responsible for running the fan while the engine is on. Unplug that & jumper the wires with a paperclip or something. Key on, that should make the fans run.

If it does, you've just demonstrated that all the fuses & relays are working OK. So you need a new fan switch.
</TD></TR></TABLE>

Alright, I jumped the wires and the fans both turned on with the key in the ON position. So I ordered a new fan switch. Thanks a lot!

Re: Car overheating, radiator fan only works when car is off?? (pyrojeff)
 

Maybe this is your excuse to flush & replace all the coolant.

But if you don't want to do that, just be prepared with the new fan switch. Swap them quickly & you'll probably only lose a few ounces of coolant.

Then for grins you can put the old one in a pot of hot water with a thermometer. Check with a multi-meter set for continuity, as you heat up the water the switch will close at it's proper temperature - or not...

Funny i was just about to post this same question. but i have a 91 honda accord and the same thing i changed all the sensors and it still doesnt turn on when the car is on only when i turn it off. what else can i look for thanks in advance. and sorry if im thread jacking

Re: (tobe2be)
 

I think there's a thread about how to check the fan timer module. I don't own one with that, so I don't know the details.

Re: (JimBlake)
 

check the engine coolant temperature sensor on the block. Same exact problem with me but on a integra and fixed it. the sensor is pretty cheap anyways

i replaced all the freaking sensors. and nothin all the fuses are good. i was just going to take a wire from ignition fuse it and throw it to the coolant fan relay. so that i can still have the function of the thermo switch. unless someone else can help me out

Re: (tobe2be)
 

Search for 'fan timer', there's threads about that around here someplace. It's not located in the fusebox, but I don't remember the details.

The fan timer is responsible for switching between the 2 fan switches. If it goes bad, it's possible for it to loose connection with the switch that's responsible for running fan when the engine is on.

The other sensors (ECU coolant temperature, gauge sender) don't share information between them, so replacing the other sensors can't help.

https://honda-tech.com/zerothread?id=1595129

thanks a lot ima check that out right now. and there is the link for anyone else who stumbles across this thread

Re: (tobe2be)
 

I also remember a thread with a picture of the wiring diagram showing the 2 sensors & fans with the timer module. Couldn't find that with a quick search just now...

ok still have this stupid problem and the actual radiator fan timer is next to the main relay. but ive noticed that the relay isnt getting 12 volts when the car is on but it does when the vehicle is turned off. ive checked all the fuses and relays and everything tests out fine. i have no idea what else to look into except fusing a wire from an ignition source to the fan relay to retain full function of the thermo switches. any clues. thanks

Re: (tobe2be)
 

Are you sure that's the timer? That sounds like the fan relay. The fan timer is a different thing.

Got a Helm book for your year?

no i dont have the helms manual. but the relay is in the front near the battery and thats the timer so i think. i took apart the glove box and there is nothin behind there. i am stumped. no check engine light or anything

Re: (Guru Designs)
 

I hate to bring up an old thread, but I need some advice.

I have a 96 Accord EX with the 4 cylinder Vtec engine. Last night the car ran hot while idling for an extended amount of time. I noticed that the fans were not running.

I've taken a jumper across the radiator fan switch that's on the thermostat housing and it only turns the fans on when the car is off. I jumped the other radiator fan switch that the lower radiator hose runs to and that turns both fans on while the ignition is on.

So, does this mean that my fan timer module is bad? b/c from what I've read here the radiator fan switch on the thermostat should turn the fans on when jumpered when the ignition is on?

I just don't want to throw parts at this thing. Any help would be appreciated.

Cam

Re: (Camshaft2)
 

The thermostat housing is the one connected to the lower radiator hose. The thermo-switch there may be bad, since it didn't turn the fans on with the car on, until you jumped it.

Re: (tech8)
 

My top radiator hose runs to where the thermostat is housed (at least it appears so). The bottom radiator hose runs more toward the back of the engine.

Also, the one that turned the fans on (with the ignition on), I jumped, was at the back of the engine.

Cam

Re: (Camshaft2)
 

The thermostat is actually behind the one that connects to the lower radiator hose, at the back of the engine.

Re: (tech8)
 

Oh.......It didn't look like it.....I guess that's where part of my confusion is coming from.

I gotta go outside and look at this again.

Cam

Re: (Camshaft2)
 

Thermostat is located behind this housing:

https://i56.photobucket.com/albums/g...8/DSC03216.jpg

This is the thermoswitch:
37760-P00-004 SWITCH ASSY., THERMOSTAT (A-93) (UCHIYA)

https://i56.photobucket.com/albums/g...8/DSC03218.jpg

San Leandro Honda link:

http://www.slhondaparts.com/br...=true

Re: (tech8)
 

Yeah, I just looked at it.....I guess I should have looked at that rear hose connection closer. That clears up my confusion. I'll replace that switch tomorrow.

Thank you for your help. I seriously appreciate it.

Cam