qaz

'86 Camaro Z28 (the carbed one). It's had 2 overheating episodes..first was when the radiator had a crack in the plastic piece, then replaced the radiator and found that one of the hose clamps was defective and not tightening up enough.

After this latest overheating problem, the fan no longer comes on while at idle, and so it overheats (it does not overheat while moving, and there is hot air coming from the heater so I don't think there is air in the system).

The fan does come on when the A/C is turned on..in fact, if it's about to overheat at idle turning on the A/C will cool it down almost immediately.

What I need to know is whether the fan in this model is controlled by the ECM or by a separate coolant temperature switch, as I think the sensor has gone bad (possibly damaged because of the overheating) and I need to know which one to check/replace. Haynes book isn't much help.

If there is a separate coolant temperature switch, where is it?

TIA,

Brian

Tim Burgess

The cooling fan is controlled by the A/C switch and by a switch in the passenger side cylinder head. With the A/C off, the fan will only come on when the temperature reaches 239 F - on the hot side of when it should really be turning on. There are fan switches available from auto parts stores (Pep Boys sells a 180 F switch & a variable switch that mounts in the radiator fins) that you can easily wire into the system. Hook one side of the fan switch to chassis ground, and the other side to the green wire on the fan relay. The fan relay should have red, red / blk, green, and brown / white wires going to it. The relay may be near the battery, or on the driver's side fire wall, near the brake vacuum booster.

Tim

qaz

Thanks, I found it and I got a replacment temp switch (it is definently the temp switch and not a wiring problem as the fan comes on when I ground the wire that goes to the switch).

The new switch did not come with a gasket..is one required or does it seal up properly without a gasket?

Brian

Tim Burgess

Use teflon pipe thread sealer on the threads on the temperature switch.

Tim