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Yes, it should work, regardless of the compressor running. Your fan under the hood, behind the condensor will not run with an empty system. Nor will your compressor.

But you should be getting your interior fan running, regardless of the AC being switched on.
 

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Yes, it should work, regardless of the compressor running. Your fan under the hood, behind the condensor will not run with an empty system. Nor will your compressor.

But you should be getting your interior fan running, regardless of the AC being switched on.
Completely agreed, though, not sure about the radiator fan or not (not saying it is not true), the compressor should have a low pressure switch that will not allow the compressor to run should you have low freon.
 

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Discussion Starter #4 (Edited)
Yes, it should work, regardless of the compressor running. Your fan under the hood, behind the condensor will not run with an empty system. Nor will your compressor.

But you should be getting your interior fan running, regardless of the AC being switched on.
Completely agreed, though, not sure about the radiator fan or not (not saying it is not true), the compressor should have a low pressure switch that will not allow the compressor to run should you have low freon.
Just double checking...........The a/c fan (not the heater/vent fan) that is in the cab should work even if the a/c system is empty?

I can't think of anything they did when wiring the new computer that would of kill the interior a/c fan? I tested the power going into the fan control knob and it has power so I'm baffeled?????

Any suggestions?
 

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Murray,
The '91 Spider I just bought with 19K miles on it had an inoperative heat/vent fan. The dealer I bought it from had the fan replaced by the local Alfa dealer (well, previous dealer who sold the car originally). That dealership indicated that THIS fan frequently failed if it was not regularly operated. Don't know whether it is the same with the AC cabin fan, but thought I'd pass this on to you and others.

Gary Knox
West Chester, PA
 

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Murray -

Sorry to hear about that. Yes, to re-confirm, you interior fan (not the heating fan), should work irrespective of the AC being on.

Not sure if the fan would even be related to the computer. And so you are getting voltage coming into the switch - and then I would assume, different readings on the "out" prongs depending on the fan setting?

Are the wires coming from the fan switch original? That is, do they match what is in the S4 manual (which I believe you have, if memory serves)?

I think you're going to be doing some head scratching here - and possibly locating the fan, and I'm not sure exactly where that is.

Perhaps someone with better electrics skills could chime in?
 

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Any suggestions?
Perhaps before condemning your wiring, try applying 12V to the motor directly and see if she spins. If not, bad motor, if she does, be sure your switch is working and if it is, follow those wires to be sure they are actually making it to your motor.
 

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u bet. i often crank down the compressor and just let the AC system use whats left of the coolness from the freon, to max-perform the car like onto a freeway or up a canyon. (hardtop makes u come up with a plan)

mt heater/blower fan has been dead from innactivity. bummer because its so much work to get to and replace that i need a better excuse. i dont even get the fan-light on the dash when i switch it on. maybe its the switch.

oh btw - theres a late-spider brand new A/C fan for sale on ebay right now. never used
 

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Discussion Starter #9 (Edited)
Perhaps before condemning your wiring, try applying 12V to the motor directly and see if she spins. If not, bad motor, if she does, be sure your switch is working and if it is, follow those wires to be sure they are actually making it to your motor.
Good plan DD, Now all I need to do is find it. :confused:

u bet. i often crank down the compressor and just let the AC system use whats left of the coolness from the freon, to max-perform the car like onto a freeway or up a canyon. (hardtop makes u come up with a plan)

mt heater/blower fan has been dead from innactivity. bummer because its so much work to get to and replace that i need a better excuse. i dont even get the fan-light on the dash when i switch it on. maybe its the switch.

oh btw - theres a late-spider brand new A/C fan for sale on ebay right now. never used
Ok this puts the pressure on, I'll look for the a/c fan in the car, test it and report back.

Here's the a/c electrical diagram for my Spider. You can see where they spliced in for the fan control in the upper right hand side for the new ECU.

There is a Condition system control unit that seems to be the master mind of the system on the right hand side in the middle that would be a good thing to check too.
 

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Good plan DD, Now all I need to do is find it. :confused:
The motor? It is up in the evap box, passenger side of the car, right above the floor. Not too hard to access (not as hard as the wiring in the dash anyways:eek:). You'll get it Murray.
 

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Discussion Starter #13
Fan Works !!

Found the reason the a/c interior fan wasn't working.................the fan ground wire was disconnected. There is a grounding station right in front of the hub of the stick shifter.

Now the question is:

If by passing the connection between pressure switch, thermal switch to control the cooling fans will that effect the engagement of the compressor?

Here's a pic of the grounding point.
 

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If by passing the connection between pressure switch, thermal switch to control the cooling fans will that effect the engagement of the compressor?
I don't want to misinform you, could you go into a little more detail about this: cooling fans, AC fan or radiator fan, pressure switch are you talking about freon high and low pressure switches-if so-which one...
 

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wow nice find msiert.

i have the exact same issue with my blowerfan and now am gonna check for grounds since even my dash-light doesnt come on when i use the fan button. (AC works well tho)

hey douglas, can you help understand what 'tar-tape' is and where i can buy it? one of the tech bulletins calls for it on AC pipes to deal with heat issues and with possible vibration (as well as a weight that AR installed in 91 that our 90s doesnt have that helps with vibration of the hose into the firewall supposedly.)

let me know if you want the exact page number of the bulletins im talking about.

thanks for your help
 

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Discussion Starter #16 (Edited)
I don't want to misinform you, could you go into a little more detail about this: cooling fans, AC fan or radiator fan, pressure switch are you talking about freon high and low pressure switches-if so-which one...
DD, I'm going to quote what Bob said he did and include the wiring diagram for that area.

The radiator fans were not functioning for me on the dyno. I had to hard-wire them to the battery power to turn them on. I don't know why this was the case. Getting tired of this, I connected the long-M1 (thermal switch to fan relay) directly to the Autronic ECU pin 49 (relay3O/P). This allows "dial-a-fan" from the fan switch temperature selection entry in the Autronic software. Works very nicely. Doesn't run the fans for A/C though.

To get the a/c to turn on the radiator cooling fans he gave this recommendation.

To keep the Alfa factory A/C controller function, you should simply join the short-M1 (pressure switch to thermal switch) to the long-M1 (leaving long-M1 connected to Autronic pin 49). I do not say that it is easy to find that wire, but it is a simple fix.

You can see from the diagram, that the M1 circuit allows either the engine temp thermal switch to turn on the fans OR the A/C pressure switch. If the thermal switch goes to ground, the fan turns on. If the A/C pressure switch goes to ground, the fan turns on. I'm thinking that the fans would not run for me either because the engine temp switch was bad or because M1 did not have continuity back to pin 86 on the coolant fan relay. I think I tested and it was the latter (from memory??).

Option 1 should work as long as you check continuity of the short-M1 circuit and the ground pin at the pressure switch terminals and as long as the pressure switch is working properly.


Hope this helps Douglas, I am just starting to learn this system and don't have an electricl back ground to understand it yet but I'm learning.

You can see where he tied into for the fan control for the new ECU in the M1 wire coming out of the thermal switch back to the relay.
 

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wow nice find msiert.

i have the exact same issue with my blowerfan and now am gonna check for grounds since even my dash-light doesnt come on when i use the fan button. (AC works well tho)

hey douglas, can you help understand what 'tar-tape' is and where i can buy it? one of the tech bulletins calls for it on AC pipes to deal with heat issues and with possible vibration (as well as a weight that AR installed in 91 that our 90s doesnt have that helps with vibration of the hose into the firewall supposedly.)

let me know if you want the exact page number of the bulletins im talking about.

thanks for your help
Tar tape is type of adhesive tape they use to insulate freon lines, you could just use foam rubber insulation from Home Depot, Lowes, etc...
 

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i looked at home depot (sorry to slightly sub-track your thread msiert but its so small it doesnt warrant a new thread imo) and they just have a metallic tape (shiny) and various Duct-tapes.

so u only get it from the household industry? foam-rubber insulation sounds like something easier to ask for the store employees to help me find. if i find it, i secure it with tar-tape or what?

thanks in advance
 

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DD, I'm going to quote what Bob said he did and include the wiring diagram for that area.

The radiator fans were not functioning for me on the dyno. I had to hard-wire them to the battery power to turn them on. I don't know why this was the case. Getting tired of this, I connected the long-M1 (thermal switch to fan relay) directly to the Autronic ECU pin 49 (relay3O/P). This allows "dial-a-fan" from the fan switch temperature selection entry in the Autronic software. Works very nicely. Doesn't run the fans for A/C though.

To get the a/c to turn on the radiator cooling fans he gave this recommendation.

To keep the Alfa factory A/C controller function, you should simply join the short-M1 (pressure switch to thermal switch) to the long-M1 (leaving long-M1 connected to Autronic pin 49). I do not say that it is easy to find that wire, but it is a simple fix.

You can see from the diagram, that the M1 circuit allows either the engine temp thermal switch to turn on the fans OR the A/C pressure switch. If the thermal switch goes to ground, the fan turns on. If the A/C pressure switch goes to ground, the fan turns on. I'm thinking that the fans would not run for me either because the engine temp switch was bad or because M1 did not have continuity back to pin 86 on the coolant fan relay. I think I tested and it was the latter (from memory??).

Option 1 should work as long as you check continuity of the short-M1 circuit and the ground pin at the pressure switch terminals and as long as the pressure switch is working properly.


Hope this helps Douglas, I am just starting to learn this system and don't have an electricl back ground to understand it yet but I'm learning.

You can see where he tied into for the fan control for the new ECU in the M1 wire coming out of the thermal switch back to the relay.
:confused:Since I know you want to keep your car completely stock *sarcasm*, you could start fresh and wire a relay to your compressor, when the relay energizes, feed a power wire to the fan, so when you kick on the AC, the fan kicks on. Too, maybe more worthwhile, is installing the relay to feed a pusher fan mounted directly onto the condensor coil to really give your ac system a big boost!!!! The only reason a fan comes on for your AC is to cool off the condensor, not to keep the engine from overheating, a nice 14-16" fan dedicated to the AC system would boost efficeincy dramatically!
Here would be a starting point for that modification: http://store.summitracing.com/egnsearch.asp?N=700+4294924500+4294839058+4294838842+400006+4294902510+115+4294775279
 

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i looked at home depot (sorry to slightly sub-track your thread msiert but its so small it doesnt warrant a new thread imo) and they just have a metallic tape (shiny) and various Duct-tapes.

so u only get it from the household industry? foam-rubber insulation sounds like something easier to ask for the store employees to help me find. if i find it, i secure it with tar-tape or what?

thanks in advance
Foam rubber-think of water heater aisles, also roll bar padding (do they have that aisle in home depot???). You can secure it with electrical tape or zip-locks.
 
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