* Under the hood in the fuse box: This is the most common location. The fuse box is usually located near the battery, often under a cover. The relay itself may be labeled, or you may need to consult your owner's manual or a wiring diagram to identify it. Look for relays that are related to the cooling system or the AC system.
* Inside the passenger compartment fuse box: Less common, but possible. This fuse box is usually located under the dashboard, often near the driver's side. Again, check your owner's manual or a wiring diagram.
Troubleshooting Steps:
Since you're experiencing both AC and overheating issues, here's a more systematic approach:
1. Check the obvious: Start by ensuring the coolant level is correct. Low coolant will lead to overheating and can impact AC performance.
2. Locate the Radiator Fan Relay: Use your owner's manual or an online wiring diagram specifically for your 1992 Grand Am to pinpoint the relay. The diagram will show which relay controls the radiator fan.
3. Relay Testing:
* Visual Inspection: Check the relay for any signs of damage, such as burnt contacts or a swollen casing.
* Swap Test: The easiest way to test a relay is to swap it with a similar-looking relay (same amperage rating) from a non-critical circuit (like the headlights). If the fan works after the swap, you've found the faulty relay. If the problem moves to the other circuit, you know the relay is good and the issue lies elsewhere.
* Multimeter Test: You can use a multimeter to test the relay's continuity and coil resistance, but this requires some electrical knowledge.
4. Check the Fan Motor: If the relay seems okay, the fan motor itself could be bad. You can test this with a jumper wire (carefully, and only with the ignition off!), connecting the power directly to the fan motor. Caution: Be very careful when doing this, as it involves directly connecting power and there is a risk of electrical shock or injury. If the fan runs, the motor is fine, and the problem is likely elsewhere in the circuit.
5. Check the Fan's Thermal Switch: This is a sensor that activates the fan when the coolant temperature reaches a certain point. It's often located on the radiator or engine block. If the switch is faulty, it may not signal the relay to turn on the fan. A multimeter can be used to test its operation.
6. Consider the AC System: Your AC issue (only cooling when accelerating) suggests a problem with the AC clutch. Low refrigerant could be the cause of both overheating (less air flow across the condenser) and weak AC. This requires an AC system diagnostic.
7. Wiring Issues: Inspect the wiring to the fan, relay, and thermal switch for any breaks, loose connections, or corrosion.
Important Notes:
* Safety First: Working with car electrical systems can be dangerous. If you're not comfortable working with electricity, it's best to take your car to a qualified mechanic.
* Wiring Diagram: A wiring diagram specific to your 1992 Pontiac Grand Am is invaluable for troubleshooting. You can often find these online through automotive repair websites or forums.
By systematically checking these components, you'll have a much better chance of pinpointing the cause of your radiator fan and AC problems. Remember that replacing the relay is the cheapest and easiest fix to try first.
