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Discussion Starter #1
Hello all, I have a 2007 EX-L RES , NAV and I've started noticing that when I'm stuck in traffic or while on a long wait through a drive thru, the temperature begins to shoot up and the engines cooling system will not turn on. I would have to turn on the air conditioning to get the engines fan to kick on to help lower the temp. :huh: still even after I do that it will only run while I have the AC on but the moment I cut it off the temp begins raise. Also when I shut off the van thats when engine fan will turn on to lower the temperature. Any insight or suggestions as to what may be causing this and or a possible fix would be great! :DD
 

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Lots of potential trouble areas. Your radiator could be clogged up or the water pump is failing.
I would start by checking to see if the engine cooling fan is coming on and seeing what color the engine coolant is.
 

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When I went to see Atlantis' final flight, I parked off the bridge in Titusville from dusk to night in ~90° heat, windows up/engine running, to keep my AC and laptop going and mosquitoes at bay, for an eight-hour-plus stretch, with no overheating or any other ill effects. A well-running car will never overheat idling or in traffic... something's up with your system...
 

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Either:

1. Bad Aux Fan

2. Bad Aux Fan RELAY (in the box, engine compartment, pass side)

3. Bad thermostat. I wrote a DIY for "Motorad thermostat" a while back.
If you have more than 80K miles, I strongly recommend that you replace the tstat.
It is cheap insurance.
$20 for Honda tstat and $15 for "Motorad" tstat.
 

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Discussion Starter #5
Either:

1. Bad Aux Fan

2. Bad Aux Fan RELAY (in the box, engine compartment, pass side)

3. Bad thermostat. I wrote a DIY for "Motorad thermostat" a while back.
If you have more than 80K miles, I strongly recommend that you replace the tstat.
It is cheap insurance.
$20 for Honda tstat and $15 for "Motorad" tstat.

thanks for the suggestions, will check relay tomorrow its raining off and on today... as for the aux fan, excuse the novice question but that's the fan that goes off or suppose to go off when the engine's temp thinks about going up? if it is then i think it might be working still because as I stated when i turn on the AC and rev the engine I hear the fan that's mounted for the radiator go off and that's when the temperature begins to lower but IF I don't turn on the AC that fan will not come on at ALL... its weird ...

the van currently has about 64xxx miles on it now.
 

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The radiator has two fans - one for the AC and one for the engine. I think cnn was referring to the engine fan. It appears that your AC fan is working okay.
 

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Discussion Starter #7
Can you point me in the right direction , where to check the relay for the aux fan ? Is it in the " primary under the hood box " as the manual refers to on page 415? Fuse location # 11 cooling fan ? Or is CNN referring to something else. Once again sorry for novice questions, but this is my first vehicle. I'm not afraid to get my hands dirty while I try to figure things out.. Thanks again for any advice / help .
 

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send me an e-mail I have a Wiring diagram , xps doc could not figure how to post here

Relay is under hood

Al
 

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If your 2007 Ody has more than 80K, I strongly recommend that you replace the thermostat because most tstats lifespan is about 60-80K range.

You have 2 options:

1. Factory Nippon 78C thermostat + gasket....about $25.

2. Motorad 82C thermostat ($15 at local autoparts store) + Honda gasket ($3).

Plus 1 gallon of coolant.

Option #2 gives you more heat in the winter.
Once you replace the tstat and your overheat problem goes away, then you are OK.

If not, then troubleshoot the electrical thingy.
 

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I highly doubt your thermostat is the issue, given your symptoms. Honda uses thermostats that are designed to fail open, so your car will not overheat if it fails. The thermostat is not a maintenance item and should only be replaced when it fails....and you'll know when it does, as the temp gauge will not rise at all and you will have no heat.

I would check:
Coolant level in the reserve tank (white bottle located behind and below the hood latch area). If it is empty, then check the coolant level in the radiator (check only when engine is cold....and first turn the cap one click to remove pressure and then open the cap). If the level is not up to the base of the filler neck, then fill it up and put the cap back on. Then fill up the reserve tank to the max level.

Have the radiator cap pressure tested, as a bad cap will lower the boiling point of the coolant, due to lower pressure. Test the cap at 13-18 psi and check for loss of pressure. If the pressure drops, replace the cap.

Check the two cooling fans and relays.
 

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...Honda uses thermostats that are designed to fail open, so your car will not overheat if it fails....
I think the Nippon thermostat has the conventional design.
The tstat that fails in open position is "Motorad Fail-Safe" type.

Back to the conventional tstat, it can fail either way: open (no heat) or closed (engine overheats).
No tstat lasts forever, I have owned several cars over 30 years, the tstat usually goes (either open or closed) at around 80K or sooner.
Another mode of failure is the prong simply breaks in half.
 

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Discussion Starter #13
OK thanks for the input .. but back my real noobish question I'm trying to find to the location of the relays in question but I do not know where they are ... are the relays essentially fuses? Sorry again for being a big dumbass..

Sent from my SGH-T989 using AutoGuide.com App
 

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Discussion Starter #14
Also if the radiator cap needs to be replace would that cause the fans not to come on?

Sent from my SGH-T989 using AutoGuide.com App
 

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Also if the radiator cap needs to be replace would that cause the fans not to come on?

Sent from my SGH-T989 using AutoGuide.com App
No, the sensor is immersed in the coolant. If the radiator cap is bad, the coolant temperature will be the same except under less or no pressure. In extreme cases, it will boil. But the sensor will start the fan long before that.

Having said that, replace the radiator cap if you suspect it's bad. (Feel for pressure in the upper radiator hose when the engine is hot.)
 

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OK thanks for the input .. but back my real noobish question I'm trying to find to the location of the relays in question but I do not know where they are ... are the relays essentially fuses? Sorry again for being a big dumbass..

Sent from my SGH-T989 using AutoGuide.com App
Like said, given your vehicle doesn't overheat while in motion and it appears you get normal heat out of the HVAC system.. and the engine will cool once you start the a/c, it sounds like something is up with the main cooling fan. Relays, which are basically electronic switches, are a common failure point, but you mostly hear of them failing closed (on position). They look like this:
 

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No they are not fuses. Relays are an electrial switch that uses low amperage voltage and ground to controll a High amperage circuit (pos or ground). thus the 30-40amps that the cooling fans require only goes through the relay and not the controll circuit PCM in this case. Also a Relay can controll 2 circuits with 1 relay where 1 is on and the other is off and vice versa

in the picture, when voltage is @ 85 and ground @ 86 then a circuit is completed between 30 and 87 , on a 5 pin relay when 85 and 86 are not active then 30 and 87A are a circuit and open circuits when activated

Al
Al
 

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Like said, given your vehicle doesn't overheat while in motion and it appears you get normal heat out of the HVAC system.. and the engine will cool once you start the a/c, it sounds like something is up with the main cooling fan. Relays, which are basically electronic switches, are a common failure point, but you mostly hear of them failing closed (on position). They look like this:
I thought these relays are for European cars (Volvo, Mercedes, BMW etc.), they use 85-86 and 30-87 terminology.

The Honda relays use different terminology.
 

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Yeah I would check the coolant level and color first, then relays, then the cap. If the reservoir tank is empty then you have a coolant leak...at this point if your not familiar with cars I would take it in to a independent mechanic.
 
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