intermittant blower, passenger side?

[coach9119]

Did some searches but came up blank.

On my 90 xj, what sounds like a fan or blower or something kicks up from behind the passenger side dash at intervals for no aparant (to me anyway) reason. It usually kicks on within a minute or so of the engine starting, runs for about 15 seconds, then stops. A few minutes later, is will go on again for 15 seconds again. This happens all the time. I haven't checked to see that it does it with the A/C on, but I suspect it does. It happens if the environment controls are off (all sliders to the left), vent or heat are on, fan high or low.

Any idea what this might be?

[8Mud]

ABS pump?

[MoFo]

I have a similar symptom on my '90 XJ Laredo. Mine is a very faint rattling sound with the same interval and pattern as yours. Mine sounds like it is coming from under the dash on the drivers side. It is faint enough and intermittant enough that I have not been able to pull over and investigate when it happens. Where is the ABS pump?

[8Mud]

On a 91, I was working on, it was on the passengers side (motor compartment). On my 95 it´s on the drivers side. On the 95, it was acting up for awhile, seemed to cycle every couple of minutes. But either completely failed or cured itself.
When I leave my heater controls, in the defrost possition, the compressor and the aux fan for the radiator, cycle at few minute intervals.

[coach9119]

ABS?? I didn't think it had ABS. I just got this rig about two months ago and I thought it had standard brakes.

NOOB question - How can I tell if it has ABS?

[8Mud]

The ABS unit is fairly large and has what looks like a windshield wiper motor as part of the valve body. Follow the brake lines from the master cylinder, if the ABS is there, the lines, will lead to it eventually. The control unit for some of the early models, was under the back seat.