PR5 overheating - radiator fans not running

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slvrPR5

:
2003 Protege5
Any advice is greatly appreciated...

Car overheats with normal driving, can avoid this by running the car's heater full blast. No visible coolant leaks, coolant level is fine and radiator cap is under a year old. It seems like the two fans behind the radiator do not come on at anytime (car on or off). They will by turning on the A/C, so at least i know the fans function.

Since the fans run with the AC turned on, does that prove the 30A "Cooling fan" fuse is good? Any suggestions for what else i can check?
 
check your ECT sensor (engine coolant temperature sensor)

I remember reading about another guy that had a bad temp gauge. It would read hot but when he got an obd2 reader and torque app it showed his temperature was normal.

Does your temperature gauge rise above half ?

Does your overflow reservoir boil ?
 
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Can the ECT sensor be checked using an OBDII reader?

Yes, temp gauge will shoot to the top if i don't blast the heater. The first time this happened, the overflow reservoir was boiling.

Torque app?
 
It sounds like your temperature gauge is working properly , so that would mean your ECT is working.

You may have a faulty thermostat. It's a valve located on the bottom rad hose that is supposed to open up when when the coolant gets hot. If it doesn't open, the car will overheat.

(I'd post a diagram but my computer crashed,... I'm trying to do this with my phone)
 
You should get yourself an Elm 327 scanner. It plugs into your OBD2 port and broadcasts via Bluetooth or WiFi to your smartphone.

If you get the torque app for your smartphone it will list the data for every sensor that your car has.

The scanner is 20 bucks and the app is free,... You can't beat that.
 
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slvrPR5 said:
PCB, wouldn't an overheating condition activate the two fans?
Click to expand...

Yeah it should I don't get what going on.

Your fans and fuses are good.

I'm thinking either the ECU or your HVAC control circuit somehow ??
 
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Check all your fuses, there may be a blown fuse that powers a control circuit.
 
OBDII scanner says P0090 which is not cooling system related. Haven't checked other fuses, am i looking at the under hood block or the one inside the passenger compartment? Any particular fuse i should be paying attention to?
 
The room fuse is definitely connected to the cooling fan system. It's fuse number 8 in the passenger compartment. The cooling fan system isn't shown in the wiring diagrams so it's hard to tell what fuse ties into what circuits.

You should probably just check all your fuses,... under the hood and in the passenger area.

CEL number P0090 isn't listed as a code for our car. Its probably another example of how different scanners give different code numbers for the same problem.
 
Do both fans come on with the A/C? I was under the impression only the passenger-side fan came on with the A/C, but I could be wrong.

Also, what happens if you turn on the A/C (thus activating the fans) while driving? Does this affect the temp at all?
 
dmention7 said:
Do both fans come on with the A/C? I was under the impression only the passenger-side fan came on with the A/C, but I could be wrong.

Also, what happens if you turn on the A/C (thus activating the fans) while driving? Does this affect the temp at all?
Click to expand...

Apparently turning on the AC does cool our car down much better even if our fans are working properly. You would think the extra heat created by the AC being on would make it hotter but the extra wind created by having both fans going, cools the car the best.

Running his AC is a good way to buy some time while he figures out what going on with his car.
 
Head gasket? Based on descriptions above, the head gasket would be my first thought, especially the 'boiling' in the overflow tank.
 
larson701 said:
Head gasket? Based on descriptions above, the head gasket would be my first thought, especially the 'boiling' in the overflow tank.
Click to expand...

His fans didn't come on,... any car will boil over without the fans working. (hoping of course that he didn't warp his head and screw up his head gasket with the over heat condition.)
 
slvrPR5 said:
Haven't checked other fuses, am i looking at the under hood block or the one inside the passenger compartment? Any particular fuse i should be paying attention to?
Click to expand...

It looks like the engine fuse (fuse #14: 10 amp) A/C fuse (fuse #4: 15 amp) located in the cab,.. as well as A/C 10 amp, AD fan 30 amp, cooling fan 30 amp located under the hood, all tie into the cooling system. There's a few fuses that feed the engine control system that might tie together both your fan problem and your FPR issue.

I'm assuming the big 30 and 40 amp fuses are OK because your fans do work and those are the main power feeds to the fans.
 
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Did a visual check on all fuses mentioned above, the look fine. The big 30 or 40 may be bad, but the fans do operate with the A/C so that may rule those out.

I drove around today, as soon as the temp started rising, turned on the A/C and the heat up full. Both fans were running and temps stayed in the middle of the gauge. While parked, the engine running, and the A/C turned off, only the drivers side fan would run.

Any more suggestions?
 
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