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MartinsMotorSport
MartinsMotorSport, BMW Technician
Category: BMW
Satisfied Customers: 86
Experience:  BMW Group Certified Technician, quilified top in class, 8 years exp, Motor Mechanic Trade Quilified
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Have a 95 bmw 318i compressor will not engage or fan when

Customer Question

have a 95 bmw 318i compressor will not engage or fan when turned on.we replaced fan relay, compressor relay,pressure switch at dryer coolant temp switch and dryer..please help
Submitted: 1 year ago.
Category: BMW
Expert:  Kenny replied 1 year ago.
I would check the ambient temp sensor. If it think it is cold outside it will not activate the compressor.
Customer: replied 1 year ago.
Inside the car says outside temp is in the 80 -90s doesn't that work from that sensor
Expert:  Kenny replied 1 year ago.
Yes it does work from that sensor. So that is not the issue. Is there voltage going to the compressor?
Customer: replied 1 year ago.
No but I can ground the black and gray wire to the relay and it comes on
Customer: replied 1 year ago.
Or I can ground black and gray wire on pressure switch next to drier and it will work
Customer: replied 1 year ago.
Had ac scanned with autologous scanner says mixing wheel has a fault whatdver that is
Customer: replied 1 year ago.
Autologic scanner
Expert:  MartinsMotorSport replied 1 year ago.
Hi
Do you still need help?
Customer: replied 1 year ago.
Yes
Expert:  MartinsMotorSport replied 1 year ago.
Let me understand,
Is your fan in the car working - speed increases and decreases?
Is your control panel showing all the functions - lighting up?
Thanks
Customer: replied 1 year ago.
Yes blower motor works on every speed.a/c switch lights up green.
Customer: replied 1 year ago.
I have changed ambient temp sensor. Evaporate temp sensor ,coolant temp sensor,pressure switch next to dryer,and compressor relay..the compressor still doesn't work neither does high speed side of fan unless I ground the wire on back side of relay
Expert:  MartinsMotorSport replied 1 year ago.
Hi here is the diagram for clutch control.
Could you please measure voltage at the fuses.
Also check if the Engine ecu hasn't suffered water damage (common problem)
I cant load image, busy sorting this out
Expert:  MartinsMotorSport replied 1 year ago.
1
Customer: replied 1 year ago.
The computers look like the just came out of the box. All the fuses have 12.05
Expert:  MartinsMotorSport replied 1 year ago.
Did you strip the bottom of the ECU to look inside?
Fuse 16 and fuse 39.
On pin 5 terminal 85 on the ac compressor relay is black/blue wire, this wire needs to earth from the engine ECU.
Please shave the wire start car and switch AC on, measure for earth on the wire and then switch AC off and measure again, need to know if the ECU is sending signal or not. Then I know where to look further.
Thank you. :)
Customer: replied 1 year ago.
Blue and black to relay is not grounded if I ground it compressor comes on
Customer: replied 1 year ago.
16 & 39 both have 12.02 volts
Customer: replied 1 year ago.
1.97 running 2.02 not running
Expert:  MartinsMotorSport replied 1 year ago.
Ok.
Stupid question, is there AC gas?
Is the pressure switch at the drier bottle new?
Customer: replied 1 year ago.
Yes full charge new dryer and pressure switch
Expert:  MartinsMotorSport replied 1 year ago.
Thanks.
You say you ground black and grey wire on pressure switch and the compressor kicks in or the Aux fan kicks in?
The other thing, the mixing wheel is the temp adjuster in between the centre vents to adjust cold hot. But it wouldn't stop the compressor from kicking in even when set to hot.
Customer: replied 1 year ago.
I can make fan work at switch by grounding black and gray wire.if I ground the other bl gr wire compressor comes on if I ground blue and black, compressor comes on only
Customer: replied 1 year ago.
And it has a code for mixing wheel.i didn't think that would cut it out either
Customer: replied 1 year ago.
I just checked codes again..
Stratification potentiometer & blower potentiometer
Expert:  MartinsMotorSport replied 1 year ago.
Do you have another AC panel to try on car?
The sensors are new, compressor works when bridged, relay works, pressure sensor also working, Got gas, no water in engine ECU.
I think the AC panel either needs coding or has a bad connection inside that isn't sending the signal to engine ECU to switch.
Customer: replied 1 year ago.
The switch panel I don't have.i have one from a 98 but it's digital this. You thimk it work just to try it
Customer: replied 1 year ago.
You talking about switch panel,or control module under console
Expert:  MartinsMotorSport replied 1 year ago.
Switch panel.
If the connector is the same you can try it :)
Customer: replied 1 year ago.
Switch panel didn't fix it..
Customer: replied 1 year ago.
I went to dme grounded blk & gry wire everything works.went to a/c control module grounded Blu &blk wire everything works just doesn't cycle stays on all the time.
Expert:  MartinsMotorSport replied 1 year ago.
Hi there is a Vaporizer sensor.
Check the connection of the white component plug PIN 22 to the vaporizer sensor. On the disconnected temperature sensor
the voltage should be at least approx. 5 volt. If the connection is operative, the component should be replaced.