My 97 stock Camaro has a problem with the high speed fan not coming on unless you turn on the AC. I suspect this is a sensor or relay problem, any help?

 

The way fans are wired from the factory, both fans should run anytime the PCM commands them "ON". When the fans run at low speeds, they are wired in a series configuration to each other which causes them to run at a slower speed. When the AC is energized, relays #2 and #3 changes the wiring of the fans to a parallel configuration which allows both fans to run at the high speed. The reason for this is because a series circuit runs through both fans wired one after the other and the total amperage draw of both fans together, slows the motor speeds down. With the fans wired in parallel, each fan is wired separately from the other and is no longer affected by the amperage draw of the other motor, allowing it to run at the higher speeds. So I'm not sure what you mean when you say "the high speed fan not coming on unless you turn on the AC" because there are no high or low speed fans.

The schematic below is from the 1996 Service Manual, but is the same as the 1997 Camaro. Hopefully, it can help illustrate what I've tried to explain above and diagnose the problem you're having.

 

The fan that will not come on unless the AC is turned on is the one on the passengers side. If I dont turn the AC on the car will run hot when at idle or in traffic. Thanks.....

 

Something I'm not clear on is, does either fan run before you turn the AC "ON" and does only the right fan run when the AC is turned "ON"? Have you checked for DTC codes? If the left fan relay, engine temp sensor or left fan motor were bad, neither fan would run on low speed when the engine is hot or in traffic. If only the right side fan runs when the AC is turns "ON", the left side relay or fan motor has to be bad.

 

Thanks for all of your help but this is way beyond my knowledge. I will take the car to a garage or have it junked.

 

Junked for a fan issue??? Its not that big of an issue.

 

should not be overheating under the conditions you mention. have you flushed the radiator yet. maybe take it out and flush so the engine and heater core are not effected. sometimes they will catch the crud coming out of radiator and cause more issues. also while your at it flush engine and heater core to get as much crud out as you can.