Originally Posted by Bustedback

When you say A/C fan, do you mean the electric radiator fan or the HVAC blower motor?

Originally Posted by Bustedback

What year is your XJ?

Originally Posted by PONCHO130

Should the fan start once the a/c is turned on regardless of temp?

Originally Posted by PONCHO130

A/C fan not engaging. Ran it direct to the battery and the fan works. What's my next step? I checked the fuses inside the engine compartment and its good. Is there another fuse?

Originally Posted by PONCHO130

Should the fan start once the a/c is turned on regardless of temp?

Originally Posted by CCKen

It sounds like the fan is not running when you select AC(?). Here's some text from the '99 FSM pertaining to the radiator electric fan operation: "ELECTRIC COOLING FAN Vehicles equipped with 4.0L and equipped with Air Conditioning have an electrical cooling fan. The fan is controlled by the cooling fan relay, which is located in the power distribution center (PDC). For the location of relay within the PDC, refer to the label on PDC cover. When coolant temperature reaches approximately 218°F, or when air conditioning is requested, the powertrain control module (PCM) provides a ground path for the fan relay. This ground is provided to the cooling fan relay through pin C2 of PCM connector C3. Battery voltage is then applied to the fan through the relay. When coolant temperature drops below approximately 209°F, the PCM opens the ground path to the relay. This will prevent the cooling fan from being energized. The cooling fan motor is protected by a 40 amp maxi-fuse located in the PDC. The fan relay is protected by a 15 amp fuse (#10) located in the junction block." A quick check of the fan circuit is to remove the electrical connector from the Engine Coolant Temperature Sensor on the thermostat housing, then start the engine. If the fan runs it shows that the fan is good, fuses in the PDC and in the JB are good, the relay is good, the wiring from the relay to the fan is good, and the PCM relay ground driver is good. If the fan does not run it shows that any one of these components/circuits could be bad. Above is a test of the engine coolant overheat protection circuit. It will trigger a CEL that can be cleared. If the fan operates doing the above test and you want to see if the AC select circuit works you can remove the electrical connector from the Low Pressure Cycling Switch, on top of the AC accumulator, and jumper the two pin cavities in the connector with a small paperclip, or a piece of 20 gauge wire, select an AC setting on the Mode Selector, start the engine and the compressor clutch should engage and the fan should run. If it doesn't, the High Pressure Cutout Switch may be Open. You can jumper the connector contacts like you did with the Low Pressure Switch (leave it jumpered) and see if it runs. If the fan runs by jumping the switch connector(s) the Freon pressure may be too low to operate the Low Pressure Switch. If the Freon pressure is up to spec, the Low Pressure Switch may be bad (rare failure). Pics to look at:

Originally Posted by CCKen

It sounds like the fan is not running when you select AC(?).

Here's some text from the '99 FSM pertaining to the radiator electric fan operation:

"ELECTRIC COOLING FAN

Vehicles equipped with 4.0L and equipped with Air Conditioning have an electrical cooling fan. The fan is controlled by the cooling fan relay, which is located in the power distribution center (PDC). For the location of relay within the PDC, refer to the label on PDC cover.

When coolant temperature reaches approximately 218°F, or when air conditioning is requested, the powertrain control module (PCM) provides a ground path for the fan relay. This ground is provided to the cooling fan relay through pin C2 of PCM connector C3. Battery voltage is then applied to the fan through the relay. When coolant temperature drops below approximately 209°F, the PCM opens the ground path to the relay. This will prevent the cooling fan from being energized.

The cooling fan motor is protected by a 40 amp maxi-fuse located in the PDC. The fan relay is protected by a 15 amp fuse (#10) located in the junction block."

A quick check of the fan circuit is to remove the electrical connector from the Engine Coolant Temperature Sensor on the thermostat housing, then start the engine. If the fan runs it shows that the fan is good, fuses in the PDC and in the JB are good, the relay is good, the wiring from the relay to the fan is good, and the PCM relay ground driver is good. If the fan does not run it shows that any one of these components/circuits could be bad.

Above is a test of the engine coolant overheat protection circuit. It will trigger a CEL that can be cleared.

If the fan operates doing the above test and you want to see if the AC select circuit works you can remove the electrical connector from the Low Pressure Cycling Switch, on top of the AC accumulator, and jumper the two pin cavities in the connector with a small paperclip, or a piece of 20 gauge wire, select an AC setting on the Mode Selector, start the engine and the compressor clutch should engage and the fan should run.

If it doesn't, the High Pressure Cutout Switch may be Open. You can jumper the connector contacts like you did with the Low Pressure Switch (leave it jumpered) and see if it runs.

If the fan runs by jumping the switch connector(s) the Freon pressure may be too low to operate the Low Pressure Switch. If the Freon pressure is up to spec, the Low Pressure Switch may be bad (rare failure).

Pics to look at: