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Discussion Starter #1
Had my A/C recharged last summer, haven't driven the car much since. Upon driving it again I've noticed that the AC coil fan (behind radiator) is on all the time when the car is running (independent of AC). The tech was trying to fix my AC (he found later that a connector had a short where it plugged into compressor and fixed that) and I don't know exaclty what he did under front hood, but he was unplugging relays and plugs trying to figure out what was going on.

What could I check to find out why its on at all times?

(PS I don't want to go back and bug him because he did it all fOR FREE cause he liked my car so much, and its not really a big problem)
 

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Discussion Starter #2 (Edited)
Any help? :)

I just went out and pulled some fuses. It seems that BOTH fans are running as long as the engine is running, both the condensor coil fan AND the radiator fan. It is nowhere near warm enough for the rad fan to be on (plus I just started the car and its not warm yet). What in the world is going on for BOTH to be on?

As an aside I noticed somebody had put the wrong size fuse in the cond fan slot (a 10A in place of a 30A) and it had blown. But when I put a new 30A in there it turned on as well as the rad. fan. So long story short the Rad fan is what I've been hearing this whole time! :mad:
 

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It sounds like your A/C system is low on freon. There is a system pressure switch up front near the passenger's side of the frunk, down low. You can pull the connector and place a shorting jumper between the contacts, of the harness. The short will fool your system in to thinking there is enough freon pressure, and hence shut your fans off. Or you can just get your A/C system recharged.


Eric
 

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Discussion Starter #5
Great! Thanks for the reply, gives me some good info to go on. This is all confusing, however, since the whole reason I went in to the AC shop was to have the system recharged. It was while he was recharging that he noticed the compressor wasn't kicking on and fixed it for me. I am quite sure it was recharged (I saw it myself) and it blew cold for the next 1500 miles/2 weeks. All the while the fans were on. Is there any other explaination??
 

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If you pull the connector and short it and the fans turn off, then you may have a leak some where. You can do this with the car off, then start it. It should only take a few minutes.
 

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Discussion Starter #7
OK, great, thanks for the tip. Is the connector extremely easy to see? Do I need to remove the inner plastic liner to see it? Is it black? Thx!
 

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Here is a link to the online BGB:

http://www.mr2-tech.com/bgb/mechanical/volume2/air_conditioning_system.htm

Go to the section titled: pressure switch. The picture is kind of small, but you can at least see the location. The switch actually interfaces directly with an aluminum pipe and is about 0.5"-0.75" in diamater. Once you pull the connector off, you should be able to short it with a paper clip or other metal piece. Just keep it off the body.
 

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Discussion Starter #9
ebaker said:
Here is a link to the online BGB:

http://www.mr2-tech.com/bgb/mechanical/volume2/air_conditioning_system.htm

Go to the section titled: pressure switch. The picture is kind of small, but you can at least see the location. The switch actually interfaces directly with an aluminum pipe and is about 0.5"-0.75" in diamater. Once you pull the connector off, you should be able to short it with a paper clip or other metal piece. Just keep it off the body.
Thanks again, you've saved me a lot of work. One last question: Would that pressure switch turn BOTH fans on? Like I posted, BOTH the Rad fan and Coil fan are constantly on. I thought the rad fan would be controlled by the water temp switch and not the pressure switch??
 

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Both fan relays are normally closed, meaning they will always run unless the A/C amplifier shuts them off. The coils for the relays are both inline with the A/C pressure switch, thus they will run unless the pressure switch is closed as well.

On the A/C equipped cars, there is no coolant temperature switch, but a coolant temperature sensor. The A/C amp is actually reading the temperature and deciding when to turn on or turn off the fans.
 

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Justin311 said:
Any help? :)

I just went out and pulled some fuses. It seems that BOTH fans are running as long as the engine is running, both the condensor coil fan AND the radiator fan. It is nowhere near warm enough for the rad fan to be on (plus I just started the car and its not warm yet). What in the world is going on for BOTH to be on?
When my water temp sensor connector was unplugged, both my fans were on high whenever I started my car. I connected it back and the fans only came on when needed. Check that plug to see if it is unplugged.

http://www.mr2-tech.com/bgb/mechanical/volume1/cooling_system/Manual_0516_0001.jpg
 

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Discussion Starter #13
OK, now I'm confused again :). Perhaps this has to do with the fact that my car is a '94, and uses 134A refrigerant, and they changed the design? Then on top of that it has power steering so its a real bear to get in there and even see whats going on. But anyways this is what I found under there (please excuse if confusing :( ):



Key:

Yellow Loop: AC Line loop - has silver "fitting" jutting out of it (in red box), with black plastic connector (I assume this is pressure sensor)

Blue Box: Electrical connector attached to assumed "pressure sensor fitting"

Green Line: Leads coming out of blue box connector, disappearing in wiring harness, then coming back out the other side of harness

Green Box: Connector on other end of green line harness

Connector in my hand: Plugs into green box.

So my assumption is that the connector in my hand is where I would want to actually use a jumper to test if the pressure sensor is tripping or not...but low and behold there are FOUR connections there. I assumed there would only be two from your explaination. So which ones do I jumper? OR do I have something wrong in my diagram?
 

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Justin, let me see if I can take a picture of the AC switch that is present in the '91. If yours is a '94, there may be enough difference that the '91 test may not work.

I'll try to get a picture posted this weekend or monday. You don't happen to own the BGB's for the '94 do you? The schematic for the A/C amplifier section would be very helpful.

Eric
 

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Discussion Starter #16
ebaker said:
I'll try to get a picture posted this weekend or monday. You don't happen to own the BGB's for the '94 do you? The schematic for the A/C amplifier section would be very helpful.

Eric
Unfortunately I don't :( I will contact some friends with 94s and see if anybody has a BGB page they could scan.....thanx again.......
 

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Discussion Starter #19
ebaker said:
You don't happen to own the BGB's for the '94 do you? The schematic for the A/C amplifier section would be very helpful.

Eric
Posted, thanks to Nocturnal. Any help Eric? I'm electrically retarded :)
 

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Justin all that really changes from a R-12 system is the fittings for diagonising, (possibly the condensor) , the oil in the compressor and possibly a few minor things.
Normally your a/c fans operate like this , when you put it on a/c your fan will run on low speed. But when pressures get to high in your compressor your dual function pressure switch will kill the compressor and cut on the high speed of your fan. If you got any questions Justin instant message me at thedarkmj.
 
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