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-   -   Overheating.. Fans dont turn on. (https://honda-tech.com/forums/honda-prelude-4/overheating-fans-dont-turn-2724620/)

niterider96cord 02-08-2010 04:07 PM

Overheating...
 
Trying to figure out his overheating problem for a while now. Also have spent time researching but havent found anything to give me an answer. Where im at is... The fans not turning on is RESOLVED but it still runs very warm, the water pump seems good as both rad hoses are about equal temp. Have taken all the basic steps to figure it out and nothing. It doesnt seem there are any problems with the system... I dont want to go one by one trying to figure it out as the weather is getting warm very quick causing the car to be hot all the time.. Thanks guys 4 n e help.

slomofo 02-08-2010 04:49 PM

Re: Overheating.. Fans dont turn on.
 
Could be a relay, fan switch, diode pack, or bad ground.

Simple solution would be to get a staple or paperclip, unplug the fan switch, and leave the paperclip/staple jumped in the harness. The fan will come on whenever you turn the car on. This will work forever or allow you to at least drive it around until you find the time to trace the wiring to find the real problem.

niterider96cord 02-09-2010 06:12 PM

Re: Overheating.. Fans dont turn on.
 
Ya this is what i had to do temporarily. It got up to 55 today and i was in stop and go traffic all day and she was getting hot. Still have no clue what the problem is. Orderd a switch in and should be here tomoro so we will see...

niterider96cord 03-06-2010 02:38 PM

Re: Overheating.. Fans dont turn on.
 
Bump.. Jumped the fans to be on when vehicle is on but it gets annoying sound like its going to fly away at any moment..
Switch that i changed out did not fix it.. Am at a loss. is there a way to test the relay? and whats this diode pack u speak of?

markwilson 03-07-2010 07:29 PM

Re: Overheating.. Fans dont turn on.
 
Hey,

Sorry i have no answers, but i have a similar opposite problem on my third gen. Both the condensor fan and the cooling fan run all the time when the key is on. Does anyone have an idea?? I have stared at the wiring diagram and i am now looking for A/C diodes because they are wired up, and it looks liek they might be the problem. Do you know where the A/C diodes are?

integra15 03-08-2010 06:46 AM

Re: Overheating.. Fans dont turn on.
 
In a 5th gen it is attached to the wiring harness below the heater core assembly. But if only the fans are running and not the compressor they it is probably a cooling system problem and not the a/c system.

pprowler6 03-08-2010 08:01 AM

Re: Overheating.. Fans dont turn on.
 
2 more things to look at... there is a radiator fan relay in the underhood fuse box and there is also the radiator fan control module that is the little box to the left of the ecu.

dpetro1 03-08-2010 09:00 AM

Re: Overheating.. Fans dont turn on.
 

Originally Posted by niterider96cord (Post 41787549)
Bump..
Switch that i changed out did not fix it.. f?

what switch did you change? the fan switch is located in the thermostat housing. also air in the system could cause the fans to not turn on

integra15 03-08-2010 10:57 AM

Re: Overheating.. Fans dont turn on.
 
"Switch that i changed out did not fix it.." Does that mean you changed the radiator fan switch?
There are a lot of things that could be causing it but that would have been my guess. Make sure you check all the fuses and relays as well.

niterider96cord 03-11-2010 08:37 AM

Re: Overheating.. Fans dont turn on.
 
I believe it was the switch. Not completely sure and the guys at jerry's auto supply were not either. The part i changed out was the switch or sensor that is right next to the EGR valve. Not the one under the dizzy.? It is the plug that i jumped to get the fans to stay on all the time when the car is on.

niterider96cord 03-14-2010 11:44 AM

Re: Overheating.. Fans dont turn on.
 
BUMP - Here's a pic if it helps at all.
http://i562.photobucket.com/albums/s...10001346-1.jpg

niterider96cord 05-26-2010 01:29 PM

Re: Overheating.. Fans dont turn on.
 
Bump. The swich i replaced above was not the right one. Jerrys auto supply ordered the wrong one and 2 months later a guy i know from there told me. So put it in and fans work like a champ now but the car is still getting hot! Summer is very close and i dont want to get stranded. Water pump is good i believe.. both the rad hoses are about equal temp. Flushed the cooling system and bled it... Still runs hot. Should i look at getting a new radiator?

codyh 05-26-2010 02:15 PM

Re: Overheating.. Fans dont turn on.
 

Originally Posted by slomofo (Post 41512631)
Could be a relay, fan switch, diode pack, or bad ground.

Simple solution would be to get a staple or paperclip, unplug the fan switch, and leave the paperclip/staple jumped in the harness. The fan will come on whenever you turn the car on. This will work forever or allow you to at least drive it around until you find the time to trace the wiring to find the real problem.

Its hard to take advise from you when i look at your car.

hahaha too funny.

niterider96cord 05-26-2010 11:09 PM

Re: Overheating.. Fans dont turn on.
 
/\ pointless post... Dont judge a book by the cover. N e thing helpful to add?

AyOhOndA 05-27-2010 12:11 AM

Re: Overheating.. Fans dont turn on.
 
If the fans aren't turning on. Check the Relay under the hood. Just grab one from a friend, or buy one they're cheap as hell. If the fans turn on, it was your relay. Have you checked the motor on the fan itself? Cuz if those go out, it dnt matter if everything is working right, your fans wont come on.

BigBlock22 05-27-2010 01:13 AM

Re: Overheating.. Fans dont turn on.
 
at what point do you notice the car getting "too hot?" if you have your doubts about the radiator you can take it somewhere and have it pressure tested or buy your own kit. a bad water pump usually makes noises but not always. the water pump has a weep hole on it so water would be coming out of if the pump was faulty. im sure you would notice a leak by the lower timing belt cover if that was the case.

codyh 05-27-2010 08:53 AM

Re: Overheating.. Fans dont turn on.
 

Originally Posted by niterider96cord (Post 42593513)
/\ pointless post... Dont judge a book by the cover. N e thing helpful to add?

Lol look at his Geo type-r. Im not making fun of him at all. I think its funny.

And all I can add to this thread thats helpfull, issssss that you need to use the damn search forum feature we have. There are like 1 million threads on this.

niterider96cord 05-27-2010 10:26 AM

Re: Overheating.. Fans dont turn on.
 
AyOhOnda- It was the fan switch (they sent me the wrong one) Fans turn on and work just fine.

BigBlock22- I notice it gets hot when i spend alot of time driving around town, alot of stop and go traffic. But no leaks coming from the the lower of the timing belt. Thats the only thing that could really come to mind, is it is the old 93 radiator originally supporting an h23 now trying to support an h22 so it just seems like that could be the kink in the system. (i dont know if they used dif size rads for the h23/h22?)

xmod supra- lol yet again a pointless post. Telling me to search does nothing especially since i have searched to no avail. This case is unique because there are no obvious problems in the cooling system, and i have looked through troubleshooting guides. It passed all the basic steps.

duanes 05-28-2010 02:55 PM

Re: Overheating.. Fans dont turn on.
 
There are two fans. The one on the passenger side is operated by the temp switch from your picture above. When the water hits 200-205 or so, it closes and powers the fan relay.

The second fan ONLY comes on it the AC is on. Normally, it will run most of the time when the AC is running, but will shut off on the highway because there is enough air flow.

When you are driving around town, does either fan come on? If not, then there is a problem with the temp sensor in the picture above since the fan comes on when the connector is jumpered.

If the fan runs and you still overheat, then a: water level is too low, b: thermostat is stuck or installed upside down, or c: radiator is plugged.

There is a final possibility - bad water pump.... but they are a royal PITA to get to.

niterider96cord 05-28-2010 03:34 PM

Re: Overheating.. Fans dont turn on.
 
/\ when you say water level you mean coolant right? There is plenty and bled the system the right way. How do i check the thermostat to see if its stuck.. or upside down?

5SpdH22 05-29-2010 01:07 PM

Re: Overheating.. Fans dont turn on.
 
Hang it in a pot of water with a thermometer in it, heat the water and make sure it opens..

Not sure about the upside down part, didn't know it could be upside down....

duanes 05-30-2010 01:29 PM

Re: Overheating.. Fans dont turn on.
 
I don't know if these particular ones can be upside down, but in many cars, the edge of the thermostat is flat. It can be inserted either way. If it is wrong, the water flow will hold the valve shut.

as 5spd says - suspend the valve in hot water (needs to be close to boiling). The spring should loosen and the valve will move. If in doubt, just replace it - they are cheap ($12).

niterider96cord 05-31-2010 03:09 PM

Re: Overheating.. Fans dont turn on.
 
Well if its only $12 i dont mind replacing it, one less thing to check of the list of what it could be. Just get an OE replacement from honda or does it matter?

duanes 05-31-2010 07:10 PM

Re: Overheating.. Fans dont turn on.
 
I put in OEM 3 years ago and have had no problem.

BigBlock22 05-31-2010 07:40 PM

Re: Overheating.. Fans dont turn on.
 
niterider96cord, if the thermostat was stock closed the lower radiator hose would not get as hot as the upper hose and the car would start to over heat around 25-30 minutes of the engine being started. if it was stuck open the car would run cooler than normal especially on the freeway and the car would take a lot longer to warm up to operating temperature in the morning. a honda thermostat usually has a small jiggle pin that usually goes on the upper portion of the housing. the spring side of the thermostat goes into the inner housing ( towards the side which water is comin out of the head) so you would not see the spring if it was properly installed. if you replace it just make sure the thermostat spring side faces away from you and the jiggle pin is in the grove that its suppose to fit into. in your case it sounds like the thermostat may not be opening all the way


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