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Discussion Starter #1
2003 Honda CRV EX 4x4 auto

135936


Recently bought this car and have been trying to fix all the issues I find.

Recently I noticed my radiator hoses were not getting hard after the car warmed up. The temp gauge would only go up 1/4 of the way. I believe that's because the previous owner put "radiator stop leak" in the cooling system (because there is white crusty stuff visible when removing the radiator cap) and removed the thermostat. If I let the car sit long enough it warms up but the radiator fans never turn on. I got the coolant up to 245F before I turned the car off to avoid blowing a head-gasket (also turning the heat on full will cool the car). The car does not lose any coolant and I stuck a funnel in the radiator and ran the motor and never got any bubbles so I believe I don't have a head-gasket leak. First thing I did was stick a paper clip in the 2 pin connector that goes to the bottom of the radiator to what I believe is the fan temperature sensor. The fans turned on so then I replaced that sensor with one from autozone. But the fans still do not turn on when the coolant gets over 230F and the temp gauge is at 3/4. I don't want to replace the thermostat yet because then I believe I will get over heating issues. The car doesn't overheat yet but I believe that's dude to the thermostat being stuck open/removed and that its been cold outside lately.

What else could I test that would cause the fans to never turn on but I can force them on with a paper clip in the fan temp sensor.

Also there is a connector next to the fan temp sensor connector that is not plugged into anything but it only has a single pin.

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There is no condenser on this car as it was in an collision and the condenser was removed and never replaced. You can see the disconnected lines on the left side.

135937
 

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Does that connector actually plug in to a sensor in the cold radiator tank? Usually the coolant temp sensor that turns on the efans is somewhere in the vicinity of the t-stat housing (top of motor). At some point, there was probably a plug/sensor that turned on the efans when the a/c compressor engaged.
 

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On that yr i believe the radiator fan switch is in the bottom of the radiator.\

CMDR,
Do the fans come on when you turn the AC switch to ON? (yes, I know the AC condenser was taken out)
You jumper the connector by the fan switch at the bottom of the radiator and the fans work, but not when the connector is connector to that switch.
Well then, either that 'new' switch is bad or the radiator is not getting coolant flow (water pump, stuck thermostat, bad hoses, etc).
I would definitely replace the thermostat with an OEM one, not an aftermarket one. Do a coolant change at the same time.
Question, when the engine is HOT, is the radiator hot? If not, that radiator fanswitch will not close because it isn't getting hot enough.
So, my guess is that either the thermostat is stuck pretty closed or the water pump is not pumping.
Buffalo4
PS: I guess you could test that pretty easily by leaving that connector jumped so the radiator fan is always running.
PPS: If turning the AC switch ON makes the fans run, then you don't even have to do that jumper on the radiator fan switch.
 

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Wonder if it’s the same way on a Gen 5......efans on switch/sensor in the bottom (cold) radiator tank?
 

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Discussion Starter #5
I will try getting an OEM sensor. I also believe the temp sensor from my 99 civic will also fit my CRV so I might try to swap them to see if it will turn on before I spend the $80 for an OEM one. The sensor in my civic is a Mishimoto that has the same part number as the one for my CRV.
 

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Discussion Starter #6 (Edited)
I believe I found the connector:

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So the connector must be for A/C as the exhaust manifold is on the other side of the engine as well as the Vtec solenoid.
 

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I will try getting an OEM sensor. I also believe the temp sensor from my 99 civic will also fit my CRV so I might try to swap them to see if it will turn on before I spend the $80 for an OEM one. The sensor in my civic is a Mishimoto that has the same part number as the one for my CRV.
I said OEM thermostat, not sensor. Does the radiator actually get hot enough to make the switch close?
Perhaps you can borrow an infrared temperature/thermometer gun to read it.
Buffalo4
 

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Discussion Starter #8
Today I flushed my whole cooling system. Flushed the radiator by itself, flushed the block by itself and flushed the heater core by itself. I replaced the thermostat with an oem one but the old one looked clean. I guess there was only crust at the radiator cap because nothing came out anywhere. I filled it back up with my clamp on funnel and waited for the car to warm up. I didn't get any constant bubbles that would indicate a head gasket issue. But the car still just wont warm up. I had my OBD2 scanner connected and the car wouldn't go over 186F and once I turned on the heater it went down to 170F. Its like the engine never warms up unless the temperature sensor is giving off the wrong readings. But I did notice that when I left the heat on it started to cool down.

I also noticed I dont have an A/C compressor. This is in its place and must be why that connector is unplugged.

135956
 

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Air in the cooling system will gradually find its way to the reserve bottle. For several days, several heat/cool cycles, check coolant level (COLD motor)) in the bottle and radiator cap (if your model has a rad cap). Add coolant as/if needed.

I don’t know what temp tstat an ‘03 has, but a ‘17 has a +/-176F tstat. All water cooled motors loose a little coolant temp when the heater is used. I observe +/-176F to 186F year round, vehicle moving/efans running.
 
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