I got my a/c working recently, but the electric engine fan doesn't kick on automatically when the a/c is turned on. According to my Helms manual it should run anytime the a/c is on. The fan does come on as normal when the engine gets to about 220* and cools it down to 180*, but I want it to come on with the a/c like it should so that my a/c is colder. According to Helms the ECM has something to do with this, but that is pretty much all it says.

Does anyone know what to check or if there is a switch or sensor that activates the fan with the a/c?
I have already replaced the fan relay, and I don't want to rig any wiring to make it work, I want it to work like it did originally.

Edit: This is 1987 Camaro 2.8 MPFI

 

There is a pressure switch on the A/C high pressure line. It is on the passenger side, has a connector with two wires. Should be a blue and a black wire.

With the engine running disconnecting the connector from this switch will tell the ECM that it needs to turn on the fan. No need to jumper anything, just disconnect it. The ECM should then turn on the fan via the relay.

Note that since the coolant temperature switch does turn on the fan, the relay is good. The coolant switch activate the relay in the same way the ECM does, by grounding terminal B.

RBob.

 

Tried that. No effect. Any other ideas?

 

Odds are the quad driver for the fan relay is bad. IOW, the ECM is bad.

Could also be the wire from the ECM to the fan relay. Pin D2 (DRK GRN/WHT) at ECM. Grounding that pin should turn on the fan relay and activate the fan. With key-on, engine-off.

RBob.