SPF Radiator Fans Wont Turn Off

Weird issue cropped up on my way home from work.It was a cool evening, so certainly no need for the fans to be on. To this day, the problem continues.

When the key is turned to the on position, both radiator fans come on immediately. Yes, the manual override switch is in the "off' position. If I flip the switch to the "on" position, the fans go to a lower speed, and the fan override light comes on. If I then switch it back off, the fans return to a high speed, and the light stays on no matter what, until you turn the key off. Then the whole process repeats. The warning light doesn't come on unless you flip the switch, and then it wont go off until you turn the key to the "off" position.

If I pull fuse #12 (HVAC/ BLOWER AND A/C SYSTEM), the fans wont come on...at all. Manual override or not. I assume that this is as intended.

If I pull fuse H (A/C COMPRESSOR) (I assume this is a fuse, not a relay, but I could be wrong), there is no change.

Relays A through D are all labeled (RADIATOR CONDENSOR FAN), but I can't pull any of them due to not being able to get the plastic cover off. Any ideas? The fuse panel seems to be mounted in such a way as to make it impossible to remove this piece with the dash attached. I'm about ready to crush the cover, and remove it in pieces.

Anyway, disconnecting the dash override switch only keeps the light from coming on. The fans still start with the ignition. Disconnecting the temperature switch next to the radiator doesn't change anything.

It sure seems like there is some sort of electrical feedback going on...maybe from a relay going bad? Anyone else had this problem?
 
I believe there are three 50 amp fuses that are located in holders near the ignition coil, sort of up against the firewall. One of these fuses controls both the air conditioning compressor and the fans, and if you take this out you can at least turn off the fans.

/s/ Chris Kennedy
 
Do you have the wiring diagram from Blas? Likely a stuck relay.
No, and that was the first thing I'd wished I had when this all started. The owner's manual has one, but it requires some page flipping to use. I'll definitely have to make the investment.
 
I believe there are three 50 amp fuses that are located in holders near the ignition coil, sort of up against the firewall. One of these fuses controls both the air conditioning compressor and the fans, and if you take this out you can at least turn off the fans.

/s/ Chris Kennedy
Thanks. I've found that by pulling fuse #12, I can shut everything off, without affecting anything else except maybe the AC (don't really need that now). You're right, as a last resort, I could pull a Maxifuse in back, but I don't think I'll need to.
 
Do you have the wiring diagram from Blas? Likely a stuck relay.
Rick,

Any idea how to get the plastic cover off of the relays behind the dash? The way they are located, the relays are so close to the edge, I can't see a way to get the cover off. I'm serious about smashing the case and pulling out the pieces as a reasonable option.
 

Bill Kearley

Supporter
1, Disconnect the sending unit and check if you have continuity to ground when cold. Is yours wired to ground the relay to activate? Sending unit could be stuck.
2, Disconnect trinary switch, may be on the receiver/drier, it be stuck.
3, Key of, over ride switch of, fans unplugged, check for an unintended ground on the ground side of the circuit.
Easy stuff to check first.
 
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Bill,

Thanks for the suggestions, I'll give those a try tonight. In the mean time, I'll pick up a couple of replacement relays just in case.
 
Bill,

Thanks for asking. Been busy with a shop construction project, so haven't made any real progress. Bought replacement relays, but haven't been able to get the danged plastic cover off. If you have a SPF, you know what I'm talking about, if not, this probably doesn't make any sense. (poor design by SPF. They must have installed the panel with the relays and fuses before putting in the dash). Anyway, I tried crushing it, but it's too soft, and just deforms. I'm going to have to cut it to pieces with a dremel tool.
 
So, I successfully cut the plastic cover off and manually tested all the larger relays, they seem good (relays A-D, and the two in the engine compartment). Haven't tested the smaller ones (E-K), but those circuits don't seem to be involved. One thing I noticed is that my relays A,B and C,D seem to be swapped relative to the diagram in the owners manual. Anyone else seen this? I haven't gotten a scope out to look at the wiring behind the panel, but I wouldn't be surprised if it's not "standard". This was an earlier car, and there was some evolution going on. I'll let you know, just a s a data point for early car owners.

After testing the relays, and finding nothing obvious, I went back to the wiring diagram to look for some connection between the fan override switch/light and fuel gage (which acts normally when with fan override switch is in the "off" position, but ceases to function if I flip the switch to the "ON" position. Weird). One thing I noticed was a diode in the fan circuit to keep the override switch light from coming on when the fans are turned on automatically. I'd like to test this, does anyone know where it is? I'd also like to test the ground(s) under the dash. Same question.
 
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