Overheating at idle with AC on - Already replaced fan clutch


TheCitrusMaster

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Ok so
I have a 2000 Mazda B3000. One day in heavy traffic on a 100 degree Texas day (just a regular day in Texas) I noticed my temp guage about 3/4ths of the way up. Also, my AC stopped blowing cold.
I took the exit ramp and as soon as I gained a little speed my temp went back to normal.
Well, over the next week of driving I noticed that if the truck had been running at least 15 minutes, and if I let it idle or was in traffic, it would start to overheat. It takes a while, and does so slowly. I would notice when the AC turn warm.
I figured my fan clutch was bad, and it was. I replaced it with a new one, and it got better. I thought it was fixed.
Now, two weeks later, my AC will start blowing warm after driving around about 15 minutes. The engine would not be overheating. I checked the freon level because I thought it needed a charge but it was fine.
Later I realized I had the same issue as before of it overheating at idle or in traffic. It doesn't do it quite as often as before, it has only done it twice in the last 3 weeks and it cooled down as soon as I turned the AC off.
Its not bad enough that I cant drive it, but I would like to be able to fix the issue, especially because having AC here in Texas is a must. Again, the AC turns warm after about 15 minutes of driving even when the engine is staying stable at operating temp.

Any idea whats going on?
 


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gungfudan

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Have you cleaned your condenser? There could be a lot of trash in between the fins. I cleaned mine the other day and you should have seen the trash that came out. I would also recommend taking the radiator out to clean the condenser are the radiator so the trash does not just build up in the radiator. Try this and see if you get any improvement.
 

gw33gp

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When was the last time you did a good chemical flush on your cooling system?
 

ericbphoto

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Cooling system flush sounds like a good idea. Radiator could be getting dirtied up. How many miles on the truck? Original thermostat? Ever had the water pump replaced? The impeller could be getting eroded and losing efficiency. I would start with a real good flush first.
 

gungfudan

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That is definitely a great idea. I would do the other as well. I know I have flushed my radiator 5 times in the past year because the original owner I think never flushed it since 94. While you are doing the flush go get some cans of foaming cleaner (probably about 4) after your flush remove the radiator and soak both the radiator and the condenser coil. Read the instructions on the back of the can. Make sure you take out the Rad because You don’t want the trash blowing back onto the radiator or vise versa.
 

adsm08

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I'll bet any money that the water pump fins are mostly gone.
 

Josh B

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I like what gungfudan said too, if you get the opportunity it is well worth checking closely.
In a way mine did the same thing and i let it go that time, and left off with the ac.
A while later my radiator began to leak and i got a new one. When I pulled the old one it was so full of trash in the lower part there was no way air could get through that lower part to cool it.
I had done lots of country road driving, both dry (dusty) and wet (muddy) weather over several years, but after having to change a starter(and dig through tons of dirt and grime getting to it) I had altered that routine.
The part on the radiator that was clogged was completely out of view when installed. Every time I'd wash I'd spray well through the condenser and radiator to flush out bugs and dirt, but the lower part is beyond direct reach of the spray, and you cannot see that area short of pulling the radiator.
I only wish(thanks to adhd) I had thought to also clean the condenser down low while having the radiator out of the way.
Haha, yep, that would also be a good time to check the pump ;)
 


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