QuestionQUESTION: Should the low speed fan (one on passenger side) turn off when the high speed fan comes on, and come back on when the high speed fan goes off? I would think that it would stay on whenever the AC compressor was running, but it doesn't and the head pressure goes up past 300 PSI. If I blow compressed air through the coils on that side the pressure drops back close to 250/275 PSI. Both relays are working since both fans do come on, any ideas as to what I should be looking for? The Haynes book I have doesn't seem to have any useful information about the how the fans are supposed to work. Thank you for your help!
ANSWER: Hi Pete,
I have the '94 and the '98 manuals which show different wiring of the two fans so I can't be certain about what is 'correct' for your '97.
It appears to me that in the '98 manual that both fans are dual speed so both should operate indentically at any time, either off, low, or high speed. The light green wire is activated only when the high speed relay closes, and the tan wire is supposed to be activated both when the low speed is required and when the high speed is required when the low/high relay is powered. If yours is wired this way I would suspect that there is a wiring issue in the fan module or if not then both fans are defective (one only runs on high, the other only runs on low).
The '94 manual shows the same two incoming wire colors from a high and low relay and going to an rfi interference module, and out of that rfi module separate wires go to the two fans but one fan gets only a blue wire and the other fan gets a yellow wire AND a brown wire. It doesn't say but it would appear that one fan is dual speed and the other is single speed but I can't say for sure. So take a look to see what your wiring is like and maybe we can figure out a way to test the fans to see if they are working properly. All fans have a black ground return current wire, of course.
As with the Haynes, the text is moot on exactly how the two fans should behave if not in parallel to one another.
Roland
PS Sorry for the erroneous 'rejection' message; I intend this to be an answer.
Hi Pete, My '94 fsm is not much help because the two fans are not labelled as to which is the low and which is the high speed. The high speed relay out put is yellow, the low speed relay output is tan and both go into the rfi module. The output to one fan is a single blue wire, the output to the other fan is a yellow wirer and a brown wire. But there is no explanation of the purpose of those wires and the fans are simillarly labelled 'radiator fan motor'. So I am not sure if one is a high speed only (the blue wire) and the other is a low and high, or if one is a high only (the blue wire) , and the other is a low and high. Can you tell me what the wire colors are going to your low only and high only fans? Roland
Question: Thanks for your input. I believe that the '97 is more like the '94 than the '98, in that the passenger side fan is a different type of motor and as far as I can tell is only a low speed fan. Still can't get my mind around having the passenger side slow speed fan stop when the other one goes to high speed. That just doesn't make any sense. Without a wiring diagram I really can't do much more by way of trouble shooting at this point. Since both fans run that means they're all right. That also means the relays are functioning properly and the temperature sensors are also more than likely working like they should because the fans do turn on and off. So once again, any ideas as to what I should do next besides continue to hunt on the internet for a wiring diagram? Pete
Hi Pete, My '94 fsm is not much help because the two fans are not labelled as to which is the low and which is the high speed. The high speed relay out put is yellow, the low speed relay output is tan and both go into the rfi module. The output to one fan is a single blue wire, the output to the other fan is a yellow wirer and a brown wire. But there is no explanation of the purpose of those wires and the fans are simillarly labelled 'radiator fan motor'. So I am not sure if one is a high speed only (the blue wire) and the other is a low and high, or if one is a low only (the blue wire) , and the other is a low and high. Can you tell me what the wire colors are going to your low only and high only fans? Roland
---------- FOLLOW-UP ----------
QUESTION: Good evening,
Took a few minutes and looked at the wiring going to the fans, and found that the one on the drivers side has at lease two blue wires going to it. I can't tell what the other ones are, they're tucked in behind the blue ones and covered with some sort of plastic tubing just a short ways from the motor. There is no plug at the motor, the wires go to a plug down at the RFI unit.
The other motor has 3 wires, one being brown, one tan and the other probably a black.
Things get more complicated if you go by the Haynes #25025 book. They identify (in the text) the low speed fan as having a 2 pin connector and the high speed as having a 3 pin connector. But... the illustration 4.9b shows how to remove the low speed motor showing the motor that has the 4 wires coming out of it. Which is the motor in the drivers side and is the one that changes speed when the temp goes high.
I just went out and checked to make sure I was telling the truth... When I use a jumper wire (with spade connector ends) in the socket of the low speed relay both fans come on. when I put the jumper in the high speed relay socket only the drivers side motor goes to high speed.
So.... if they run both fans on the low speed relay they would have to deenergize that relay when they energize the high speed relay so as not to have the power going to both the low and high windings in the motor at the same time. Seems a bit odd, but that may be the explanation I was looking for although that doesn't help with getting more air through the condenser coil to keep the head pressure down in the AC system.
Pete
AnswerHi Pete,
Thanks for that information. I can't understand two things: the driver side motor, while it does have 2 blue wires, they are shown in the fsm to be connected to a single blue wire from the rfi (in parallel), as is the ground wire similarly 'doubled'. So that driver side motor can only go at a single speed with only one circuit...and yet you say it goes at low and high. I can't understand how that is done unless the rfi puts out different voltages?
And again, if the passenger side has 2 different color wires and a ground wire, why does it only go 1 speed (low) in your car? It would help to know what is inside the rfi box.
Roland
