Constantly Operating Electric Fans - Toyota Nation Forum : Toyota Car and Truck Forums

toored · 07-14-2006, 06:54 AM

Both engine cooling fans on my 1986 Camry are running all the time; even when the engine is cold. Has anyone experienced this on a Gen 1 car and could it be one of the water temp sensors at fault? If so which one and where would it be located?

Thanks for any help in this matter!!

camryfour · 07-14-2006, 08:45 AM

Both my 2nd Gen Camrys do this.

89_3SFE · 07-14-2006, 12:05 PM

Make sure the wires are all plugged into whatever they need to be plugged into. I noticed when I replaced my thermostat and unhooked the fan cable from the water temp sensor that the fan automatically turned on. I think it's a safety feature. Check that first and if everything's hooked up and working, then replace the water temp sensor.

toored · 07-15-2006, 07:57 AM

Thanks for the suggestion 89_3SFE.

I checked all the connectors and everything is intact. I also checked the cooling fan switch (on the water inlet) with a meter and it checks ok (continuity from pin to ground below 181 deg. F and no continuity above 194 deg F). With this switch logic in mind, I suppose the wire going to the temp switch may have a break in it somewhere. However, I suspect that something else in the system is at fault, like another sensor or relay stuck on, etc.

I will keep searching. Thanks again.

***toyomoho*** · 07-15-2006, 05:28 PM

When the ignition is turned on, it appears if the water temp is above 194F, the water temp switch is turned off cutting power to Relay No 1. This relay controls power to the radiator coolant fan (not A/C radiator coolant fan). With relay on, there is no power to the fan. With relay off, there is power. This relay might be located in a relay box on the left side of the engine compartment.

The only other power source for this fan is through both Relay No 2 and 3 (in series). Relay No 3 operates with the A/C magnetic clutch. Relay No 1 and 2 are energized when the ignition switch is turned. Try pulling the RDI fuse and see if this stops the radiator coolant fan operation. If so, check out Relay No 1.

rezzle · 07-15-2006, 06:07 PM

Quote:

Originally Posted by toored

Both engine cooling fans on my 1986 Camry are running all the time; even when the engine is cold. Has anyone experienced this on a Gen 1 car and could it be one of the water temp sensors at fault? If so which one and where would it be located?

Thanks for any help in this matter!!

Errr is your AC on or is your HVAC venting set to defrost?

every time the AC is on there is a good chance the engine cooling fan is on and blowing air over the condenser to keep the head pressure down.

toored · 07-16-2006, 07:18 AM

Thanks again for the help folks.

The HVAC vent is not set to defrost, which I guess - like most cars - will command the condenser fan on whether the AC is on or not. However, both cooling fans (radiator and AC condenser) are running all the time with or without the AC turned on and engine cold or hot.

Considering what toyomoho said about relay logic it appears that one (or more) of the relays may be bad. I am going to try to get a good wiring diagram of the system and try to determine what is common (power or ground) to both fans.

I understand that the radiator fan is commanded on above 194F but are both fans commanded on together when the engine temp is at a certain level, regardless of whether or not the AC is on? And what does RDI stand for?

I appreciate the help!!

Doctor J · 07-21-2006, 09:27 AM

Try the simple test:

Locate radiator fan thermoswitch in the thermostat housing (engine end of the lower radiator hose);
Disconnect wire from it;
Connect jumper from this wire to the block.
Turn ignition on.

If fans are off now, replace the switch. If fans still on, check relays by substitution.

toored · 07-21-2006, 10:57 AM

Thanks for the suggestion Dr. J.

I have not jumpered the temp sensor wire to ground yet. However, I did check for continuity from the sensor center conductor terminal to ground through the sensor and it does have continuity when the sensor is cold, as it should. As I understand it the sensor should be closed until temp reaches 195 deg., then opens and deenergizes fan relay nbr 1 which turns the radiator cooling fan on(correct me if I'm wrong), but I'm not sure if it turns both fans on at the same time.

I have changed Fan Relay #1, #2, and #3 (thinking one of them could be stuck energized/deenergized). No luck so far. I also have another temp sensor but don't expect it to fix it since the other one checks good with a meter.

It is possible that the temp sensor wire has an open curcuit some where. I'll look for that. I'm certainly open to further suggestions.

Thanks again for the help!!

Toored

Doctor J · 07-21-2006, 12:30 PM

Inspect sensor wire connector to make sure that sensor wire is not pulled in, and its teminal is actually makes connection with the switch.
Next step would be to diconnect the connector from A/C pressure switch and short it out.

toored · 07-22-2006, 08:22 AM

Hey Dr. J I finally found the problem!!

It turns out, as you suggested, that the AC high pressure switch is apparently failed open. I jumpered the connector last night and the fans operate as they should. (Yipee!)

I was studying the wiring print and it appeared that the temp sensor circuit is the only thing common to both fan circuits.

I need to replace the high press switch but I'm not sure if it is attached to the receiver dryer on a shrader valve connector or not. Would you happen to know?
Thank you so much for the help!! I just love the Toyotanation website!!

An unrelated question: Would you happen to know what controls the torque converter lockup solenoid on this car? There appears to be 2 speed sensors - one integral to the speedometer and one on the transaxle. Does one of these control the lockup function? My converter locks up every time the transmission up-shifts. I can't find a diagram anywhere that shows this system. Again, any help is greatly appreciated!!

Doctor J · 07-24-2006, 11:05 AM

I am not sure, if the high pressure switch has a shrader valve on 86 application. However you still can use a/c with jumper instead of switch: in such position, the fans with a/c on will run on the low speed (connected in series), and will run at high speed (parallel), once engine reaches its operational temperature). Unless a/c is overcharged, such use should not cause damages.
We use this "cheating" on 1988 Corolla.
On 86 camry, if it has A140e transaxle, the lock-up signal is sent from computer and based on the input from TP sensor, and two speed sensors. Generally speaking, if the throttle is above idle, both speed sensors are working, the speed is above 45...50 mph and coolant temperature is above low mark on the gage, the lock up should engage. For more specific details refer to Autoshop.101, by K.Sullivan, technical articles, electronic transmission controls. You can split a small wire from the lock up connector on the transmission, and connect other end to the small light bulb such as 7219 or 73. Place this bulb in easy -to -see location and attach other lamp's term. to the ground. Once car is driven you can see if signals to lock-up solenoid are sent (lamp on) and if lock up is actually taking place ( rpm drop and more direct responce to the throttle manipulation).