Cooling Fan trouble shooting
01-19-10, 10:36 AM
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Cooling Fan trouble shooting
I have been trouble shooting my cooling fans for sometime now and need help with one answer.
My question is does the thermo-switch located next to the water temp-sending unit behind the water pump activate (serve as ground for the g\l wires) for relays 1 & 4 controlling the cooling fans?
To date I have checked all relays, all good, traced the wire coming out of my ecu and grounded it. Cooling fans activated, and grounded the single wire coming out of the aforementioned thermo-switch, which, when grounded, activated the fans. I am currently using a ground switch to turn the fans on manually. Also when the temp reaches approx 97c the fans come on at low speed. I believe this would be relay #3, not sure. I am running a PFC with datalogit software and have all of my fan settings set at 86c. I did find where I could remove the thermo-switch and test it with hot water and an ohmmeter but it is not easy to get to. I guess I am hoping someone will be kind enough to verify if it is the source for ground on those two relays or if the ecu is supposed to use the temp from the water temp sensor next to it. By the way, my commander does readout water temp which appears to be correct so if the ecu is supposed to use that input to send ground I have a bigger problem. Thanks RD
My question is does the thermo-switch located next to the water temp-sending unit behind the water pump activate (serve as ground for the g\l wires) for relays 1 & 4 controlling the cooling fans?
To date I have checked all relays, all good, traced the wire coming out of my ecu and grounded it. Cooling fans activated, and grounded the single wire coming out of the aforementioned thermo-switch, which, when grounded, activated the fans. I am currently using a ground switch to turn the fans on manually. Also when the temp reaches approx 97c the fans come on at low speed. I believe this would be relay #3, not sure. I am running a PFC with datalogit software and have all of my fan settings set at 86c. I did find where I could remove the thermo-switch and test it with hot water and an ohmmeter but it is not easy to get to. I guess I am hoping someone will be kind enough to verify if it is the source for ground on those two relays or if the ecu is supposed to use the temp from the water temp sensor next to it. By the way, my commander does readout water temp which appears to be correct so if the ecu is supposed to use that input to send ground I have a bigger problem. Thanks RD
01-19-10, 10:47 AM
#2
In a nutshell, here is how the fans work: There are 4 relays. Fans are wired in parallel, so speeds are same for both. Relays 2&4 operate in parallel, too.
When the relays come on:
* Relays 2 & 4 controlled by PCME, come on when temp reaches 221F.
* Relay 3 controlled by thermoswitch, comes on at 226F
* Relay 1 controlled by A/C switch.
How fan speed affected by relays:
* Off, none on
* Low speed comes on when relays 2 & 4 are active.
* Med speed comes on when 2 & 4 are on plus _either_ 3 or 1 comes on but not both
* High speed comes on when all are on.
Other facts:
* The fan controller can bypass the 226 thermoswitch and fake out the relays 2 & 4.
* Grounding the test lead _immediately_ turns on relay 3.
* When you ground the test lead then the fan controller waits 2 min and turns on 2 & 4.
* If the test lead grounded for 2 minutes before engine shutoff, relays 2,3,4 will be kept on.
So there are several permutations depending on what the driver does and the state of the car.
When the relays come on:
* Relays 2 & 4 controlled by PCME, come on when temp reaches 221F.
* Relay 3 controlled by thermoswitch, comes on at 226F
* Relay 1 controlled by A/C switch.
How fan speed affected by relays:
* Off, none on
* Low speed comes on when relays 2 & 4 are active.
* Med speed comes on when 2 & 4 are on plus _either_ 3 or 1 comes on but not both
* High speed comes on when all are on.
Other facts:
* The fan controller can bypass the 226 thermoswitch and fake out the relays 2 & 4.
* Grounding the test lead _immediately_ turns on relay 3.
* When you ground the test lead then the fan controller waits 2 min and turns on 2 & 4.
* If the test lead grounded for 2 minutes before engine shutoff, relays 2,3,4 will be kept on.
So there are several permutations depending on what the driver does and the state of the car.
04-18-10, 11:49 PM
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May i ask you a quick question too?
When i turn my key to ignition on, my cooling fans working full speed. I guess this is wrong. Also when i drive normally, the fans still working full speed.
So i guess my problem is that thermo-switch ( that on the backside of the coolant level sensor ) too?
Thx a lot
Andi
When i turn my key to ignition on, my cooling fans working full speed. I guess this is wrong. Also when i drive normally, the fans still working full speed.
So i guess my problem is that thermo-switch ( that on the backside of the coolant level sensor ) too?
Thx a lot
Andi
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04-19-10, 11:39 PM
#8
unplug the relays in sequence to see which one(s) are keeping the fans on. unplug #1 (A/C triggered relay), then #3 (thermoswitch triggered relay), then #2 and #4 (2 and 4 are wired in parallel and can be triggered from the cooling fan control module or the ECU). see this thread about where the relays are: https://www.rx7club.com/showthread.php?t=876767
04-25-10, 11:37 AM
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I checked the fans again, when i turn the key to on ( i dont know the correct word for, i mean not starting the engine ) the fans work 100%. So i disconnected 1 fan-relay after the other one.
There are 3 Type B relays and one Type A relay ( its the top right in driving direction ) - when i disconnect the Type A relay, the fans doesnt turn.
So is my Type A damaged or is this quite normal that fans doesnt work if Type A isnt connected?
I am a little bit lost...
Ah, the relay is the no 1 relay on that picture:
There are 3 Type B relays and one Type A relay ( its the top right in driving direction ) - when i disconnect the Type A relay, the fans doesnt turn.
So is my Type A damaged or is this quite normal that fans doesnt work if Type A isnt connected?
I am a little bit lost...
Ah, the relay is the no 1 relay on that picture:
05-02-10, 02:59 AM
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Yes i did and all four relais were fine. I orderd a new water temperature sensor from ray, i guess that things broken. I had a similar problem on my 944, the fans doesnt turn off and killing your battery. I will report again.
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