86 Spider overheating up hills: pusher A/C fan?

[Fred Sacks <fredsacks@domain.elided>]

At 10:42 PM -0400 9/19/01, alfa-digest wrote:
>Date: Wed, 19 Sep 2001 14:12:42 -0700
>From: Brad Karp <bkarp@domain.elided>
>Subject: 86 Spider overheating up hills: pusher A/C fan?
>
>Many thanks to the several generous souls who responded to my earlier note,
>inquiring about my 86 Spider Quad's overheating while going uphill.
>
>Suggestions included:
>
>	- thermostat
>		*** I should have mentioned that it was replaced when the
>		    engine was rebuilt in the summer of 2000--sorry.  ***
>	- bypass restrictor in hose from heater (hmmm, still need to 
>check this)
>	- mixing coolant/oil (head gasket?)
>		*** No problem here; no discernible mixing, and again, the
>		    whole engine was rebuilt, with new cylinder head and new
>		    head gasket, in summer of 2000. ***
>	- pusher fan in front of AC condenser
>		*** possible eureka, read on... ***
>
>(Again, the radiator was refurbished and the water pump is new.)
>
>The last suggestion, the pusher fan in front of the AC condenser, 
>seems promising.
>
>This morning, I turned on the AC (I hardly ever use it here in the 
>beautiful Berkeley weather)--fan to max, cooling to max. The 
>compressor came on, and cool air came out of the interior vents. (I 
>had the belt replaced and system charged by Monza when they did the 
>engine rebuild in the summer of 2000.)
>
>But the pusher fan in front of the AC condenser did not come on! So 
>I assume it also fails to come on when the temperature sensor on the 
>radiator fan cowling should trigger it (to help with cooling when 
>conditions are causing the engine to run hot).
>
>Two questions for the list, now:
>
>	1) Is it certain that the pusher fan should be on whenever the
>	   compressor is on? (I think it should, but just making sure.)
>
>	2) When I'm driving uphill for a few miles in hot (>90 F) conditions,
>	   AC turned off, would not having the pusher fan helping airflow to
>	   the radiator make a big enough difference to cause the car to
>	   overheat?
>
>	   I presume that having the AC condenser in front of the radiator
>	   makes the radiator less efficient, and the temperature sensor to
>	   trigger the AC fan would not have been added by the factory if it
>	   weren't really necessary, but I suspect people on the list may have
>	   concrete experience with how much of a difference the pusher fan
>	   makes for engine cooling when the AC is off.
>
>Many thanks again,
>- -Brad, bkarp@domain.elided
>86 Spider Quadrifoglio, daily driver


Brad--
Just repaired the same problem in my 89 Graduate...Here goes...

First, the fan should NOT run whenever the a/c is on.  It is 
thermostatically controlled, by a bi-metal switch that attaches to 
the fan shroud.  When the temp reaches about 200 degrees (on my car) 
the fan switches on.  It will usually continue to run after the car 
is shut off, as it has direct fused current from the battery.

I'm going from the easiest to hardest diagnosis, as doing so saved me 
time and agravation.
If you want to go end to end (as is the proper way to diagnose any 
problem, be my guest)

First check the fuse on the drivers side wheel well.  It is a 20 amp 
yellow fuse that plugs into the circuit.  Bingo...In my case, the 
fuse had disintigrated, and had to be removed in pieces with a 
needlenose pliers (disconnect batttery if this is the case).  Put in 
a new fuse and ran the car until warm, and the fan came on at 200 
degrees.  Took less time than writing this e-mail.

If this is not the case, reconnect the battery and check the circuit 
at the fuse for aprox 12v.  If no power at the fuse, check the wiring.

If there is power, check for voltage at the switch on the fan shroud. 
If there is no power at the switch, check the wiring.  If there is 
power at the switch, short the switch and the fan should come on.  If 
this does not work...

Remove the front grill (4 screws) and disconnect the connector to the 
auxilary condensor fan.  Attach jumper wires to the connector, and 
apply 12V power.  If the fan works (I'm told that they are prone to 
seizing) then the problem is in the wiring or on the bi-metal switch 
(Good luck finding a replacement.  I tried and was told that they are 
no longer available by both IAP and Algar)  You may have to rig up a 
driver actuated switch.

Good luck, and hopefully it's just a disintigrated fuse.

Fred

89 Graduate with a brand new top today...Out in a thunderstorm 
without a drop inside.

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