fordecan

Hello, I have a 98 Cherokee Sport 4.0. Roughly 40% of the time the electric radiator fan stays on well after the car is turned off. The car is not running hot. It is at or under 200 degrees when turned off. I have researched these threads quite a lot and have tried the 'usual' fixes. I put in a new fan relay switch, changed out the electric fan thermostat on the thermostat housing. The problem persists. Went to Autozone today and they had a theory that it might be the AC high pressure switch.. Sounds likely? Could I test the theory on the high pressure switch by simply disconnecting the wiring to the high pressure switch? Or, other ideas?

P.S. - Not sure if related, but the AC has been iffy for the last couple years.. Randomly kicking in here and there in the summer when used heavily. Does not run for more than 5 minutes or so and then we turn it off and wait a while again.

Sorry for the laundry list - just mainly trying to figure out the electric fan issue and then on to the AC. Thanks for the help!

Harrison6609

Sounds like a relay problem to me. My cooling fan relay went bad a few years ago and it made my cooling fans stay on. Maybe you bought a bad one... :/

BlueRidgeMark

Yes, that would be a good test.

fordecan

Thanks BlueRidgeMark, I will try disconnecting the wiring to the high pressure switch.. I am hoping that there is no risk by doing so of doing any potential damage to the AC unit? I will post a reply with the results..

fordecan

So, I disconnected the wiring to the AC high pressure switch and ran the car around town. The electric fan do not run at all, no matter what setting I had the HVAC on.. The card did not get hot - so not sure if it would have kicked on for Temp or not.

So, I replaced the AC pressure switch and plugged back in - ran the car around town and alas the e-fan still stays on about half the time after turning off the car. I had a suggestion from someone to cycle the ignition switch a couple times without turning on the car and magic - that actually turns off the e-fan.. That same person thinks this would then be a bad ignition switch 'cause the e-fan thinks the car is still on.. Does that sound accurate? I would think maybe there would be other symptoms if the ignition switch was going bad besides just the e-fan staying on? Getting closer...

LiamLikeNeeson

I think my ignition switch might be going bad also. But it's the opposite. The acc power won't work all the time so the radio, cigarette lighter, electric fan and other things don't work and I have to jiggle the ignition key around to get it to turn on.

fordecan

Yeah, today my fan did not even bother to cycle on and off, just pegged on the entire end of my ride... Then did not turn off at all regardless of cycling the on off switch - so, I am back to wondering if it is something to do with the relay. Could the pins in the PDC where I put the relay be bad with corrosion, etc? If so, how do I properly clean it without doing damage.

My test now will be to move the relays around and see if one works better than the others.. Maybe I did get a bad new relay?

LiamLikeNeeson

If I'm not mistaken, Cruiser54 would say to use a good electronics cleaner but it depends on how much corrosion there is.

fordecan

Ok, I have a history of doing this and I just did it here. I over-analyze things. Long story short is I misread how the relays were mapped on the PDC cover and put the new relay in the wrong slot! Funny... Not. Discovered this as I decided to just start moving them around in the PDC like musical chairs.. Found the bad relay when I put it in starter relay slot and the starter kept cranking while the car was running. Problem solved. On to smaller issues..

FYI - today I noticed that if I gave the PDC a (gentle) whack it would both stop the efan when it was in that slot or the starter from cranking when I had it in that slot. I take that as a sign that it was sticking vs broken.. A potential way to discover this stuff..