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Topic Review (Newest First)
08-17-2011 12:40 AM
Mykii I need to watch this as well.. I'm having similar issues, but I replaced my radiator and got an electric fan. The shop that put in the radiator said that a specific fan would work, they put it in and it was destroying my radiator... so they bought me a new radiator and a bigger fan and mounted it nicely. Anyway, I'm just like you in the case that if I switch my A/C on, I overheat at idle. Other than that, I can drive all day--and I'm in Vegas.... My air is cold though, but the A/C lines are really hot!!...

Help us out!!
06-04-2010 02:56 PM
Viscous fan clutch is bad

Try a new viscous fan clutch, it is a simple and cheap repair, and a common problem on mechanical fan engines
06-04-2010 12:59 PM
zizax Update: radiator is fine. Temps stays relatively even across the entire grid. Coolant reservoir is okay too, coolant entering and exiting evenly and regularly. Coolant doesn't look too bad, but a little am will drain, flush, refill and burp it this weekend...and test the water pump as guided. Also, recharged the A/ improvement...still intermittent craziness once the Turd gets warmed up.
05-28-2010 02:48 PM
zizax Excellent! Enjoy the tanning. I'll be sweating under my hood.
05-28-2010 01:25 PM
rrich Whether or not the AC kicks in or not, or does it fast, won't overheat the cooling system. The cooling system is designed so the AC can be on all the time. If it cycles too fast it's probably low on refrigerant, the AC may not get as cold as it should, but won't contribute to the engine overheat condition.
To prove it doesn't affect the cooling problem, unplug the low pressure sensor on or next to the drier. (A rubber plug you squeeze to take loose.) It won't come on at all like that.
Still overheats?

Never had much luck with aluminum radiators - too much electrolysis going on. Iron block, brass heater core, aluminum rad - too many dissimilar metals. It ends up corroding and clogging too easy. Plus they hold LESS coolant.

If the radiator was the problem, replacing it with the aluminum one will fix it - but so would a new stock one, or anything that wasn't plugged.

The industrial type will outcool and outlast the aluminum ones anytime.

Please be sure to post here how it turns out. We are leaving for a few days, wife wants to work on her all-over tan.
05-28-2010 12:50 PM
cntrybmpkn86 If u buy an after market radiator I would recommend an aluminum one. they disapate heat alot fast than a stock or steel radiator. They cost quite abit more but well worth the money. You can find them at or in there magizine. And if you change the water pump get the flow kooler brand. They are made for more off road use and they push more coolant than stock.
05-28-2010 12:47 PM
zizax Thanks...and for sure I will. Going to Harbor Freight tonight to pick up the thermo. Will scour the system for air leaks too. I am thinking your diag on the coolant reservoir is spot on...seems every time I look at it, its always the same. May be coincidence but i doubt it.

Still, you think the overheating problem is not related in any way to the a/c problem?
05-28-2010 12:47 PM
cntrybmpkn86 also I would go buy/barrow an A/C gauge set. If the A/C is low or to high on freon it will cause the compressor to kick in and out real fast and cause it to burn up. I dont remember what the pressures should be but call an A/C shop they should be able to tell you. Check the high pressure side along with the low pressure side. The orifice tube might be clogged up to. that is an easy fix but u have to recharge the system after changing it.
05-28-2010 12:13 PM
rrich There are lots of "upgraded" radiators around.
The ones I like are the "industrial" type - hard to find. Most rad shops aren't familiar with them, mainly because the profit margin is low.
The "high efficiency" types that rad shops promote have extra fins - but no good for off road. Too many fins to let enough air through. They are great for high speed race cars 'cause the wind is forced through. But will overheat at low speeds - ask me how I know! LOL

The "industrial" types have larger tubes (holds more water) and the tubes are krinkled (slows the water down.) They are made for stationary engines and road grader type uses where the air isn't forced by speed. The number of fins is about the same as stock.
You have to ask several radiator shops before you find one that understands.

Most shops deny their existence, and they have to be custom ordered - the factory has to cut the core to your size. About 50% higher cost too. But they sure do work! Go look at a tractor or road graders'.

But first CHECK IT - use the laser thermometer or have a radiator shop do it.
05-28-2010 10:15 AM
zizax ok...thanks. I am going to check it out this weekend. put on my detective cap...your info will help me know better what to look for. Do you have a recommendation for an upgraded radiator if I need to replace the stock one?
05-27-2010 03:59 PM
rrich If the AC clutch was failing it would be slipping. You'd see metal filings around the pulley area and sparks would fly out of it when engaged.
Not the problem you've described.

You can have a small leak so small coolant doesn't leak out, but since air is thinner than coolant, air can be drawn in. Sometimes it will still seep coolant there slightly, mostly a stain. Pressure testing rarely shows it, as the pressure closes the tiny leak. It leaks on negative pressure - vacuum.

But watching the catch jug is a good indication - when it's cooling down it pulls the air in past the tiny leak rather than sucking the coolant from the jug.
Not always a hard and fast rule, but it is a big clue. We have to be detectives, Sherlock.

It's a coolant flow problem. By the idle raising a little it flows better, cools better.

My guess - radiator is plugged. New they are marginal at best. It doesn't take much to plug them.
05-27-2010 03:00 PM
zizax Thanks rrich...I'll go get a thermo and test the radiator. No leaks per my inspection about a week ago but not sure about the reservoir and will definitely check that out. Will try to get to the pump this weekend too. 06 has an electric fan...which shop says is all good, kicks on and off at correct temps.

If the clutch on the a/c compressor was failing, could it put a bigger strain on the engine than normal from the a/c? You know, now that i think through it, the S belt was squealing a bit after the last hard rain we had. maybe the pump is acting up.
05-27-2010 02:23 PM
rrich When you turn on the AC the computer increases the idle speed a little. It increases the flow volume.
Since it stays cooler like that I'd check several things:

The fan clutch - slipping? When it's fully warmed up is should be hard to turn by hand on a stopped engine.

A radiator shop will have an infra-red laser thermometer that they can use to measure your radiator in several spots across it. Warm it should be an even temperature all over it. If it has hot and cool spots it shows it's plugged in the cool spots.

Or - Harbor freight sells that infrared laser thermometer - $30? Good investment, useful for lots of things.

Look for any signs of leaking (hoses, connections etc) - not that you are losing coolant, but when it's cooling off it creates a suction that pulls coolant out of the catch tank. If it leaks air in somewhere, it won't pull from the catch tank and will get air inside the cooling system - air pockets do not cool. Catch bottle stays the same level hot and cold - a big clue it's sucking in air!

A pain to do - but a more frequent problem than you'd think - the impeller in the pump slips on the shaft.
Remove the lower hose and the serp belt - slide a hammer handle up into the pump to hold the impeller - try to turn the pump from the front. It shouldn't budge!
05-27-2010 12:57 PM
2006 TJ A/C and Overheating Problem

After searching through the threads I couldn't find much to help with this...

My TJ has been having some issues. Without the a/c on, it will run hotter than normal and even shot up to about 260 yesterday in heavy traffic. With the a/c on, it runs hot (above 200) always unless on open highway. For the first three years it never ran over 200 degrees except on the hottest days. So, a few months ago I changed the thermostat...kept stock. No change. Had a wrench check it out this week, they cleaned the throttle body, adjusted the idle up a bit and reported NO problems with the cooling system.

The other part of the problem is with the a/c, which the shop also reported no problems with. The a/c will run and cool while the jeep is moving, but at idle it stops blowing cool and clicks in and out far too frequently. When it does, it affects the idle speed and once triggered a MAP sensor error...hasn't done that for a while. But it does nearly kill the engine at times. I am not sure the a/c problem is related to the temperature problem because it'll still run hot without the a/c on...but it sure doesn't seem to help.

Any ideas from this limited explanation? I am getting hot and so's the jeep.

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