Overheating and whirling noise with A/C on

minimull

TJ Enthusiast
Original poster
Supporting Member
Joined
Nov 11, 2020
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157
Location
Arizona
Yesterday, my 2004 TJ overheated on me. I turned it off and waited until it cooled down and drive home with the heater on. Super fun in 100+ degree heat wave. When I got home I popped the hood again and let it run without the ac on and it did great keeping the temp constant. Then I turned on the AC and after a few minutes watched the gauge start climbing. I also noticed a whirling noise only when the AC is on. The AC still runs super cold. Last year I replaced the radiator, hoses, heater hoses, water pump, fan clutch, thermostat, belt, idler pulley, and tensioner. As far as I know the AC system is all original with around 100k miles in the Arizona heat. How do I troubleshoot from here?
 
Yesterday, my 2004 TJ overheated on me. I turned it off and waited until it cooled down and drive home with the heater on. Super fun in 100+ degree heat wave. When I got home I popped the hood again and let it run without the ac on and it did great keeping the temp constant. Then I turned on the AC and after a few minutes watched the gauge start climbing. I also noticed a whirling noise only when the AC is on. The AC still runs super cold. Last year I replaced the radiator, hoses, heater hoses, water pump, fan clutch, thermostat, belt, idler pulley, and tensioner. As far as I know the AC system is all original with around 100k miles in the Arizona heat. How do I troubleshoot from here?

You can start with checking coolant levels and since you didn't mention the radiator cap check on that. Also a good hose flush of the rad and condenser coils can be beneficial.
 
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Do you think the whirling noise is coming from the fan clutch? What brand did you use when you replaced it?
 
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This post has a list of the recommended parts... including the fan clutch...


-Mac
 
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Replace the rad cap first.

Do you remember what brand thermostat was put in? Possibly not fully opening. I would stay away from Motorad.

If the noise is only with the AC on, it's probably just the compressor.
 
Replace the rad cap first.

Do you remember what brand thermostat was put in? Possibly not fully opening. I would stay away from Motorad.

If the noise is only with the AC on, it's probably just the compressor.

I also recommend staying away from Motorad radiator cap. I have MOPAR cap now and now the fluid does not boil over.
 

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Update: I went out of town right after I posted, got back last night, so when I got ready to leave for work this morning I checked the coolant and it was a little low, so I topped it off and put the cap back on. I drove to work and then back home with no issues. It’s about. 15-20 minutes drive. Shortly after I got home I left again to drive my son to practice which is another 15-20 minutes, no problem. Then on the way home about 3 miles away my temp went from barely above normal to topped out red in less than 30 seconds. It was crazy fast! I immediately pulled over and turned off the engine. Steam was coming out of the grill from spattering coolant. I popped the hood and waited until it cooled down to normal operating temperature and tried to start it again with the heater on to limp home, but the battery was now dead, which seems really strange. My husband came and I used his jumper box and by then it wasn’t even too hot to touch. With the heater on, it only went two miles before i had to pull over again and have him tow me home. I usually buy all mopar parts unless they’re no longer available, but I’ll go back and check my records on the cap, water pump, fan clutch, etc. Is it just a super weird coincidence that my battery pooped out, too, or is there some way that can be related even though those are two completely unrelated systems?
 
High underhood temperatures could knock off an almost dead battery.

Slipping or no belt could fail to turn the water pump and alternator explaining both overheating and dead battery. Heck your crank pulley rubber may have completely seperated and it's just spinning inside.

-Mac
 
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Heck your crank pulley rubber may have completely seperated and it's just spinning inside.

THIS

Happened to me recently and I thought it was another bad water pump, which was bad anyway, but a slight detour and the timing chain was replaced since I took off the balancer.
 
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Great news, I finally had time to troubleshoot. I topped off the coolant, jumped the battery and watched as the temp climbed. I noticed coolant leaking down the thermostat housing, but realized it was coming from the upper rad hose, so I waited for it to cool down and adjusted the hose further onto the neck and tightened the hose clamp just in case it was just pushed off from the increased pressure while overheating. While I was waiting for it to cool down, I went to check my parts stash and I found an new mopar radiator cap, so I tried it out and problem solved. I've never had a cap go bad on me before and wow, I didn't realize how vital it is to the system. Thanks for the help and reminders to check the rad cap first. I'll definitely be keeping a spare cap from now on.