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Need electrical advise!

6K views 17 replies 6 participants last post by  lowesguy 
#1 · (Edited)
Have 3 days off next week and going to do some work on Dieter!
the problem is both aux fans come on at hi speed for 60 sec or so when car is cold,then for 5 min come on intermittently,engine temp is at 40 on the gauge ,once temp at 80 fans don't come on any more .
the system seem to be working backwards? they should come on when engine starts over heating,so anyway wires look OK at the 2 prong sensor on the head,connections are good for the fans at receiver dryer area,removed the big spring looking thing bolted to the frame and cleaned the connections , once the engine is warmed up I can jumper the sensor on the head and fans come on hi speed ,like their supposed to,so what would cause the problem? a/c system has no charge in it ,no Micky mouse connections that I can find? could a bad relay cause the problem? seems to be temp related,remember they only come on when car is bone cold,prob goes away once warmed up.all fuses changed with updated ones
any Ideas? guess I have to get my electrical hat on and dig up the complete wiring diagram for this circuit
any Ideas welcome in exchange for an ice cold one HaHA!:surrender:
 
#3 ·
MAYBE they come on in an overheating situation, but their PRIMARY function is to bring down excessive high side a/c pressure. I'm at my Mom's house for Mothers day and away from my manuals, but I think you'll find them actuated by the trinary switch at the receiver/dryer. Since it's a later model than mine, it could be that they are also actuated by a coolant temp sensor circuit.

Good luck with it. I will try to remember to look at the wiring diagram when I get home.
 
#5 ·
I'd be more inclined to think the fan switch would be the problem if you can jump the plug connections and get them to work. Since the a/c is empty, the drier switch and resistor block won't have any bearing. There are 2 relays in the fuse box that operate the fans(pre resistor & aux fan), however the coolant temp switch is what seems suspect to me. Have you tried wiggling the connector with it connected to the switch?
 
#8 · (Edited)
Ok I'm back,have to work Mothers day,so...I cooked up some great food for her tonight,You know whats the simplest thing of this problem? when I think about it,has to be the sensor on the the head shorting out! when its cold Its completely bonkers and once warmed up behaves itself
for got to add CCU in dash has been re soldered and all the buttons work

so far found these parts associated with AUX fans at AutohausAZ
1)Radiator Fan Controller/Resistor; For Auxiliary Fan
2)Radiator Fan Relay; Orange with 40 Amp Fuse
3) AC Cutoff Switch; On Cylinder Head; Blue Insulator with 2 Prong Connector; 130 Degree C
 

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#9 ·
The resistor block cuts the voltage on the fans only when the a/c is on. The fan relays should be the silver type w/1 having a black top & the other having a blue top. The coolant switch has a built in resistor, if it ever gets wet it will short it out. On my '93 3.2 the switch is located on the waterpump. Here in south Texas we need all the cooling we can get so I soldered a resister between the wires on my coolant switch to turn my fans to high speed at 85c. If the resister fails it defaults back to the switch.
 
#14 ·
I'm looking at coolant sensors at Autohus Az,confused on the correct one for purchase to fix my problem
the blue 2 prong one is the one I need I'm pretty sure,AC Cutoff Switch; On Cylinder Head; Blue Insulator with 2 Prong Connector; 130 Degree C

but they also list the 4 prong one,Coolant Temperature Switch; Black with Round Top and 4 Pin Connector; For CIS and Cooling Fan Control ,I do have one of those on the rear of head,so which one do I need? the 2 prong blue right?
whats the 4 prong one for? is it for fuel management?
 

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#18 ·
Problem resolved! installed new sensor that's what the problem was.also here's a trick for my nasty cracked,crumbling connecter to the sensor.
I got a trailer connector at Lowe's,cut it down,pinched it a little so it fits snugly,soldered and heat shrink. no more annoying fans when cold,feels good to get this car back up to par,now on to getting the car to pass emissions,system is not holding pressure,no whooshing sound when I remove gas cap,pretty sure the small hoses way up in the recess of tank are leaky or charcoal canister
 

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