95 S4 Cooling Fans Won't Turn On

[taos_skier]

I have a 95 Esprit s4 and the cooling fans will not come on when the AC is on and sometimes the car gets hot (mid 90's) when I idle.

I have the CD ROM manual for this car, but can't seem to find a wiring diagram.

I need to know where I can find one (if I even can)

and does anyone know if it has a high pressure switch that activates the condenser cooling fans.

If a mechanic could wire the fans so they come on when the AC switch is turned on (obviously not a factory fix!), is that a bad idea? Just trying to find a solution so I can charge and run my AC. My suggestion.... not my mechanic's!

Any insight or suggestions for where I can get an electrical wiring diagram for the AC and/or whom to contact would be greatly appreciated. I have a really great mechanic, but without these data, we can't proceed to diagnose the problem.

Thank!

[s4simon]

Hi Steve & welcome to the Forum

I have the revised wiring harness diagram for the Aircon in front of me. I'll take it to work tomorrow, scan it and email it over to you.

I'm no wizz on Aircon & I can't see no High Pressure switch anywhere, just a low pressure switch which is connected between the ECM and the ACU Control Module.

The diagram is under Section ML - sheet 7 (Aircon Revised harness diagram).

[scoule]

The fans should already kick in when the AC is turned on. Since the fans don't seem to work on engine temp or AC, you probably have either have blown fans fuse(s) or a duff relay.

Do the fans spin freely by hand? (Check with ignition OFF)

[taos_skier]

Thanks very much s4Simon and Scoule. I'll take this info to my mechanic. If you could email the scanned wiring diagram to taos_skier@yahoo.com, I'd really appreciate it. He needs this to find the correct relay and fuse.

-steve

[scoule]

Thanks very much s4Simon and Scoule.   I'll take this info to my mechanic.  If you could email the scanned wiring diagram to taos_skier@yahoo.com, I'd really appreciate it.  He needs this to find the correct relay and fuse.

-steve

<{POST_SNAPBACK}>

Just one thing to add, if the AC is very low on gas, the A/C compresor and hence the fans won't cut in when the AC is turned on. If you hear the compressor clutch clonk in, the fans should start.

If you can find the otter switch, short the two wires to it together to see if the fans kick in. If the fans kick in with it shorted but not when the engine is hot, the otter switch is probably faulty. If the fans don't kick in with the otter switch shorted, you need to check fuses, relays and the fans.

Good luck!

[pitstoppete]

Just one thing to add, if the AC is very low on gas, the A/C compresor and hence the fans won't cut in when the AC is turned on. If you hear the compressor clutch clonk in, the fans should start.

If you can find the otter switch, short the two wires to it together to see if the fans kick in.  If the fans kick in with it shorted but not when the engine is hot, the otter switch is probably faulty. If the fans don't kick in with the otter switch shorted, you need to check fuses, relays and the fans.

Good luck!

<{POST_SNAPBACK}>

if its an S4/SE/GT3 etc, the fans are controlled in the ecu, (unfortunately)not an otter switch (easy to short out like i did on my excel with a seperate switch for traffic jams etc) like an excel and maybe the N/A esprit. if the a/c is topped up enough, and they still dont come on, sounds like a relay/fuse prob? in the memcal chip, the fans on with the a/c on, up to a certain speed where they turn off to let the air whizzing in cool the condensor. this setting is changed a bit in the later chips I read somewhere (see marcus's web site about chips). signal comes from the VSS in the back hub. (it knows your speed and gives it to the ecu)

(all this is somewhere in the EMH supplement , uses it for boost purposes too IIRC)