Let me preface by saying I'm not a car guy, so if you could dumb down your explanations I'd appreciate it.

Last night I was stuck in really bad traffic and my 2002 CRV began to overheat. I pulled over and the coolant reservoir was steaming and bubbling. If you didn't know any better you would think the coolant was boiling. There was some coolant that had sprayed out on the fan and a couple of other spots on the engine, and it was dripping onto the ground underneath the car, but 1) it wasn't actively spraying; 2) I couldn't determine where it was coming from; and 3) it wasn't a huge amount.

I waited a little bit and replaced the coolant in the reservoir and topped off the radiator (the radiator didn't take much coolant), and made it home ok.

This morning I ran the car for about 10 minutes. Temperature gauge looked ok, nothing was dripping from the bottom of the car, and I couldn't see any leaks. The only coolant I saw appeared to be leftover from last night.

My question is this: Do you guys know of any circumstance that would cause the issue I described last night, but where there also wouldn't be a leak and the car would be ok after replenishing the coolant?

(Also, in July my brother in law replaced the radiator and thermostat. Not sure if that's relevant or not)

Appreciate any help you can provide!

 

Usually the hoses would burst first, and then the radiator. Look for cracks on the upper and lower hoses. Did your brother miss putting back any of the hose clamps by any chance?

 

Yes, if your coolant fans are non-functional, it could do that. Assuming the brother-in-law got stuff right.

 

This happened to me when my radiator fan wasn't turning on in a high temp location. Coolant sprayed out from the reservoir cap, luckily nothing was damaged. Make sure both your radiator and condenser fan are both turning on. If not, could be something simple like a blown fuse, relay(easy). Could potentially be the temp fan switch(sensor located at the bottom of the radiator) which is a little harder to replace. Start with the easy stuff first.

 

Not as far as I can tell. The upper hose connection is on the other side, and since the "leak" was up high I'm guessing that rules out the lower hose? I did do a check of all of them, and I didn't see anything...

 

This is interesting. Should the fan kick on automatically at normal operating temperature? When I was running the car to test it, it got up to normal temps but the fans didn't start running. I didn't think much of it because I wasn't sure if that was normal. Is testing the fans just as simple as letting the car run until it's at normal temp, or is there something else I need to do/check for?

 

The fans for this gen take forever to kick on. Usually takes a little higher than operating temperature to get them to cycle. A real PITA when you're trying to bleed the coolant. To make sure they at least function, you could turn on your ac, both fans should come on right away. To test if They come on under normal conditions, either let it run for a good while (takes about 10-15 minutes. Sometimes 20 depending on the weather). If you don't feel like waiting forever, revving the engine at around 3k rpms for a little bit should get the engine temp to the point that they will turn on.

On a side note, since you boiled over(since you've found no leaks, I'm assuming), you more than likely got some air in your system. I'd recommend bleeding your coolant to avoid performance issues down the line.

 

Thanks for this info, I appreciate it. A/C hasn't worked in a long time, but I did drive it for about 30 minutes this morning and everything seemed OK -- temperature gauge, coolant levels, etc. When I parked, I left the car running and immediately checked the fans, and they were not turned on. I'm guessing this was because the car was in motion and there was cool air rushing through it, so I'll check it again tonight.

I'll also pick up a new fuse and relay and see how it goes.

Also, when you say I should "bleed" the coolant do you just mean burping it?

Thanks again. I appreciate the help. Sorry if these are dumb questions.

Thanks!!

 

Hey no worries. You gotta ask questions to learn right? Haha. Honestly before you go out and buy fuses and relays, just pop the AC on real quick and check to see that the fans spin up. Even if the compressor doesn't kick in the fans should still turn on, the AC could be a fuse or relay issue in itself depending on what you mean by not working. If either the relay or the fuse is blown, one or both won't turn on. Then at least you're not spending money unecessarily. And yes, bleed is burping the coolant lines. You essentially just let the car run with the rad cap loose for 20 mins or until the fans cycle twice. Squeezing the upper and lower radiator hoses helps this as well in my experience. Bring lots of paper towels.

 

Ok Polka, I have an update. I checked the fuses and relays and all were OK. So hopefully that means the problem is the temperature sensor, which you suggested. Is there any way to determine for surer that the sensor is the problem, short of just replacing it? Also, maybe worth mentioning: when my brother in law replaced the radiator, he put the temp sensor from the old radiator into the new radiator, but it leaked a small bit of coolant. We put some plumbers tape around the sensor and that stopped the leak. Possible that is somehow related to the issue here?

Can't say it enough, but thanks again for all your help!

 

You test the sensor by reading its resistance while heating it with water or heat gun in the range of operating temperatures.

 

Unplug the connector to the fan switch at the bottom of the radiator. Using a small paper clip or wire, jump the two terminals on the harness side connector. Turn the ignition switch to the ON position (car not running). Does both cooling fans run strongly? If only one fan runs, that may be the cause of your overheating in traffic. Both fans suppose to run at the same time.

 

Like Tech8 said, unplug the temp switch, use a paper clip to jump the plug(pop both ends of the paper clip into each side of the female plug), and turn the key to on(without starting it). Both fans should spin up at full speed. It's possible, unlikely but possible, that the plumbers tape may be inhibiting some of the heat transfer to the sensor. If it was leaking, more than likely the gasket was bad, or overtightened. Taking it out and testing it with applied heat like canister mentioned, requires draining the radiator. I believe you could get the same desired effect by testing the voltage of the switch by leaving it in the radiator, and getting the car up to operating temperature (not sure what the correct voltage is, but I'm sure it's on Google). This is probably the better option than removing it and applying heat, as you will have the switch heat up to the specific temperature it is designed to function at, rather than over or under heating it. Just be careful not to burn yourself! If it turns out that you do infact need to replace it, I strongly recommend getting an oem switch. I went through about 4 aftermarket switches that didn't work. Oem switch worked like a charm. Found it new on eBay for $12.

 

Thanks for the info everyone.

Last night I tried to 'jump' the switch with the paper clip, as you described, with the key turned to acc position. Neither the AC nor the radiator fan kicked on, but I did hear clicking coming from above me. I could not tell where exactly it was coming from since I was under the car. Assuming I did the process correctly (which, frankly, is no guarantee), any ideas what that clicking means?

I'm going to pick up jumper wire on the way home and see if I can test the fans using direct current from the car's battery. I saw that suggested on this site, which also suggested testing the switch like you guys explained.

 

The ignition switch needs to be in the ON position, not the ACC position.

 

Sorry, I think I misspoke... the key was turned to the final position before actually starting the car.

 

Unusual for both fans not to run. Check under-dash Fuse No. 14 (10A) and under-hood Fuse Nos. 1 (20A) and 4 (20A).

 

The clicking you heard was likely the relay. That's good as it denotes voltage is getting that far. Usually located on the drivers side fender well in the fuse/relay box. Replace the sensor. Normally most sensors read at 5 volts power and oms depend on what there job is and where they are at as far as engine temp closed loop or open...ECT. Could be a "brand new bad" thermostat. But unlikely although nothing surprises me anymore.

 

Strange that neither fan turned on. It's a long shot, but check your ac compressor clutch fuse, seeing as how your ac doesn't turn on either, it could be related. I think on the first gen crvs, that fuse had some kind of control over the fans too, but I'm not 100% sure. Worth a shot. Highly unlikely that both fan motors are blown. How does the wiring harness look at the connector, are the wires beat up? Possible that there is a short somewhere.

 

Since both fans do not run when you jump the fan switch harness connector, replacement of the fan switch currently would be useless. If you heard clicking, that may be one or both relay coils getting energize to close the respective relay contact(s). There are separate relays (an A/C condenser fan relay and a radiator fan relay) for the separate fans. You need to check/test the fan circuits further before anything else.

These relays are normally-open type of relays.

The way the relay works is when power (+) and ground (-) are applied to the relay coil, the coil is energized and the relay contacts closes; thus allowing power (+) through the relay "now closed" relay contacts. There is only one terminal for ground (-).

Under-dash Fuse No. 14 (10A) provides power on the respective relay coil side. When the relay coils have power (+) from under-hood Fuse No. 14 and ground (-) from the fan switch or PCM, it gets energized.

Check under-hood Fuse Nos. 1 (20A) and 4 (20A). These are the fuses that provide power to the respective fans when the relay contacts are closed.

 

When you say the sensor, you mean the temp sensor/temp switch, right?

 

I think I see what you're getting at, but just as background info the a/c doesn't work because the condenser is shot. (it has been this way almost as long as I've had the car, but I'm a freeze baby so I never bothered replacing it.) The connection at the temp switch is bent at almost a 90 degree angle, but otherwise I think it's fine? I'm not sure if that sort of bend is ok or unusual. There is nothing notable about any of the other connections as far as I can tell.



Lol most of this may as well have been in Portugese it went so far over my head. Makes me realize I have a lot to learn! That said, I did check the fuses under the hood that you referenced and both are good according to my fuse checker tool. I also checked the a/c fan and radiator fan relays under the hood by swapping them with my horn relay, and both worked.


As for the under-dash fuse, I just want to make sure I have the right one. According to my diagram the #14 fuse is RC mirror. Is that correct?






And I just want to make sure I have it right, because this is what the dash fuse box looks like. Yikes.

 

1. Yes, that is the correct under-dash fuse. That fuse protects the following circuits: A/C compressor clutch relay, A/C condenser fan relay, Blower motor relay, Heater control unit-panel, Power mirror switch,Radiator fan relay, Rear window defogger relay, Recirculation control motor, Seat heater relay (Canada: EX-L).

2. With the fan switch connector jump and ignition switch to ON, you can also test for power at the Blu/Blk (blue wire with blk stripe ) for radiator fan motor, and the Blu/Yel wire for the condenser fan motor.

 

In this diagram, I added some notes to try to illustrate what needs to happen. Think of the relay contacts kind of like a draw bridge. It needs to come down (close) to allow power through from the other fuse.

 

I was referring to the sensor/switch It's job is effectively that? TECH 8 Has paved a ROAD for you. This dude is good!