I tried jumping the green wires from the 2 relay's located on my firwall to tehe fans and it worked for the drivers side fan but the passanger side still doesnt engage. Both relay's are on the firewall right? I have a 1991 Z28. Also the fan switch is new.

 

one fan is engaged by the coolant temp. and the other is engaged by the air conditioning. only one should come on

------------------
86 IROC-Z
305 TPI
700R4 W/ shift kit
3.23 gears
T-Tops
maroon with gold stickers and rims/ black interior
43,000 miles
flowmaster exhaust, edelbrock headers, gutted airbox, converter, and MAF, K&N filters.

soon to come are 3.73 gears and subframe connecters.

 

But I put a switch on that grounds both (2 green white wires coming from seperate relay's on the firewall) Shouldnt that bypass the fan switch?

 

Seems like you only bypassed the relay that is controlled by the ECM (primary fan).

Try grounding the wire that goes to the fanswitch located between #6 and #8 plugs in the head. This energizes both fans on my '89, but at a minimum it should energize the 2ndry fan.

 

Yep, disconnect the plug between the #6 and #8 plugs and ground it. It should definatly kick both fans on since if the second fan relay is energized, the triggers the first fan relay to fire, regardless of computer control. If this doesn't turn on the second fan, unplug the relays (pass front fender) and swap both plugs on the relays. If it works the 2nd relay is bad (which is now where the 1st fan is wired).. Still nothing either both relays simultaneously failed (unlikely), a wiring problem (fusable link on the pass side core support melted)...

There's other possibilities, but most likely its one of these... Hope this gets ya cooled down.

 

Both relays are beside the radiator on mine, ('88 GTA originally, in a truck now). I have both green/white wire hooked to each other. When the primary fan comes on, so does the secondary fan. Both are controlled by the ECM instead of waiting for the pass. head temp switch or the AC to call for the second fan.




------------------
_ ___ _
SMasterson

 

I bought both relay's new and replaced them. I'm going to jump the fan switch tommorow from the head but will it make a difference since I already jumped them at the relays?

 

I would think it should be the same, but I've never tried it.

FYI to the MAF guys...Mateo's is Speed Density, since he doesn't have MAF (or the two relays for the MAF control and burnoff), GM moved the fan relays to the firewall.