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Discussion Starter #1
Dears, I have that problem make headache for me. That both fans running continually even before engine starting. I have a doubt that was the relay I took it out then try to test it it's clicks ok, then I put the ignation on and put relays back I never heard that clicks and fans running again. Please help. I have 2001 Camry 4c
 

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Both fans? AC and radiator? Either climate control is bad, constantly running in Max AC, what makes both fans run or, you have sort somewehere. if it were just bad temp sensor, only radiator fan will run.
 

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Discussion Starter #3
Both fans are running all time even climate hot or cold or engine hot or cold
 

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01 Avalon XL, 03 Avalon XL
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Which Toyota model vehicle? Which trim level (XL, SE, XLS, etc.)? What year was it built?
 

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01 Avalon XL, 03 Avalon XL
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Thanks. Do you have an automatic heating/cooling, where you set a temperature on a digital readout and the system maintains that temperature? Or do you have a manual heater/airconditioner control with knobs?
 

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That's good. As ukrkoz said in post #2 above, your system thinks that you have the air conditioning on all the time. Is there any chance that your dashboard controls have gotten jammed? On my 01 Avalon, which is in many details a Camry, I have an a/c switch that toggles (push in and it's on, push again and it's off) and another switch to choose between outside air and recirculating cabin air -- and yet another for heater fan speed. Any one of these could fail and cause problems.

If you're pretty sure the cabin controls are working fine, then I'm out of my league, and my factory service manual diagnostics cover only the automatic type.

It is relatively cheap to purchase a new fan relay and try switching out one of the old ones and replacing with the new... and do that for both fan relays. Engine cooling fan relay on ebay can be bought for $US 15 or so; a/c clutch/fan relay is more, $US 36 to $US 50.
 

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Thanks my dear, I going to do this and try. Also I have had the controls unite out before to change the radio and I have did some cleaning on whole ac/heater control maybe it caused some hidden damaged, overall it's working properly with out any faults.
 

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I had a similar issue after installing a used engine in my 97 Camry. I found the bottom radiator ATF sensor disconnected. The plastic plug harness was damaged and it wasn’t making the proper contact. In addition inspect your water temp sensor wiring plugs or the sensor maybe defected. i would follow the recommendations of our friendly subscribers as mentioned before.
 

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The fan system on these cars has a fail-safe design: if ANY component is failed or unplugged, the system will run all the time, just like you're experiencing. The question is, which component failed.
Could be any of the following:
Water temp switch (at the bottom of radiator)
AC pressure switch
Broken wire

If one of first two is open, or there's a wire that is broken, your fans will run all the time with ignition on. If both fans run with ignition on, it's unlikely to be the relay unless both relays failed at the same time (did you check all 3 fan relays? yes, there are 3 total).
If the AC control box is stuck, then you would have fans spinning at half speed with just ignition on and engine not running, as fans only go full speed when water temp is high of AC pressure is high (you cannot have high AC pressure with engine off). Unplug the AC pressure switch (by the pas strut tower, on AC line) with ignition on, engine off: if fan speed ramps up, then AC panel is a maybe; if fan speed stays same, then AC panel is fine.

My money is on water temp switch.
 

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Discussion Starter #12
The fan system on these cars has a fail-safe design: if ANY component is failed or unplugged, the system will run all the time, just like you're experiencing. The question is, which component failed.
Could be any of the following:
Water temp switch (at the bottom of radiator)
AC pressure switch
Broken wire

If one of first two is open, or there's a wire that is broken, your fans will run all the time with ignition on. If both fans run with ignition on, it's unlikely to be the relay unless both relays failed at the same time (did you check all 3 fan relays? yes, there are 3 total).
If the AC control box is stuck, then you would have fans spinning at half speed with just ignition on and engine not running, as fans only go full speed when water temp is high of AC pressure is high (you cannot have high AC pressure with engine off). Unplug the AC pressure switch (by the pas strut tower, on AC line) with ignition on, engine off: if fan speed ramps up, then AC panel is a maybe; if fan speed stays same, then AC panel is fine.

My money is on water temp switch.
Thank you for this valuable information, I really confused now, I have checked all the 3 relays as I mentioned when testing it out its works and clicks when 12 V go through, but when to put it back fans running without that click, also the Water Temp Sensor connection I have checked it's ok even the sensor itself I have tested it, it's reading resistance. I think I have to have 3 new relays and new water temp sensor just to get my self out of that headache
 

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On my 96 Avalon 1MZ-FE, same engine as yours I had this issue and discovered under one relay the female blade terminal had gotten pushed down and was not plugging into the relay. SO bend the tab on the terminal and plug it up into the holder for the relay. This fixed the fans being on all the time. I think it was a ground terminal
 

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Thank you for this valuable information, I really confused now, I have checked all the 3 relays as I mentioned when testing it out its works and clicks when 12 V go through, but when to put it back fans running without that click, also the Water Temp Sensor connection I have checked it's ok even the sensor itself I have tested it, it's reading resistance. I think I have to have 3 new relays and new water temp sensor just to get my self out of that headache
These are "normally closed" relays, the opposite of a regular "normally open" relay. In other words, the relay opens when the power is applied, closed otherwise.
Like I said, it's a fail safe system: the fans are ON until turned off. This normally happens the moment you turn the key on, so you don't notice the "turning off" part, but it's there. In your case, something failed, and the fans are not being turned off - so the normally closed relays are not energized and are not opening (turning off) the fans.

You can replace the relays, but I highly, highly doubt they're your problem based on the symptoms you're describing. Did you do the test for climate control panel/half speed I explained?

The water temp sensor in the radiator is an on-off switch, not a resistor. It should be closed (no resistance, or few ohms at most) until it reaches 180F or so, then it's open (infinite resistance). Same thing for the AC pressure switch.
 

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You need to troubleshoot all components that send a signal or call for the fans to turn on. You have a switch(es) that have failed in the on or closed position as slavie indicates above. Remember a relay is just an electro-magnetic switch.
 

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On my 96 Avalon 1MZ-FE, same engine as yours I had this issue and discovered under one relay the female blade terminal had gotten pushed down and was not plugging into the relay. SO bend the tab on the terminal and plug it up into the holder for the relay. This fixed the fans being on all the time. I think it was a ground terminal
So to be more concise. Pull the relay, I think the middle relay and look down into the female socket. You probably have a female blade connector that has gotten pushed down and is not making ground contact with the relay. So reach under and try to push the wire up so it locks. You may need to bend the small tab on the blade connector so it engages the stop in the plug which keeps it from falling downward. This worked. If you need I can post a picture of which relay block. It is I believe on the driver side of the throttle body.
 

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So to be more concise. Pull the relay, I think the middle relay and look down into the female socket. You probably have a female blade connector that has gotten pushed down and is not making ground contact with the relay. So reach under and try to push the wire up so it locks. You may need to bend the small tab on the blade connector so it engages the stop in the plug which keeps it from falling downward. This worked. If you need I can post a picture of which relay block. It is I believe on the driver side of the throttle body.
296518
 
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