1994 Chrysler Lebaron Convertible In traffic with the a/c on, with an ambient temperature of about 75 degrees, my temperature gauge moved to within a needle's width of the top of the normal zone, higher than I've seen it in the 6 years I've owned it, although I've used the a/c in 95 degree heat many times. Getting out of slow traffic and traveling 65 - 70 mph on Interstate 395 didn't cool it down at all. I was sure it would. It was only 75 degrees outside and getting air into the grille has always lowered the temp in the past. Instead, the gauge stayed where it was. Then, I turned off the a/c while still traveling at about 65 mph and the temperature immediately began to return to normal operating. Before going on the Interstate I pulled over and verified that the fan was spinning. The air coming out of the back was seriously hot. It wasn't a hot day and I wasn't in bumper to bumper traffic very long. What could be the problem. With the compressor on, the fan runs intermittently but constantly. With the compressor off, the fan only runs when a certain temp is reached. Shouldn't the temp have returned to normal operating with the compressor on as well?
If the cooling system is functional, yes.
The ac condenser adds heat to the air coming thru the radiator when the ac is on. If the engine cooling system is weak, the extra heat will make the engine run hot.
Low coolant flow thru the radiator is a common cause.
Testimonial: "I understand. However, the radiator, water pump, thermostat and related hoses are all new. There is no problem when the compressor isn't running. There are no issues until the temp gets to a certain point and then it simply can't recover with the compressor on. What surprises me is that even on a 95 degree day I could get the temp back down simply by running it at highway speeds. Now it doesn't help even on a 75 degree day. I'd have to say that the cooling system isn't weak, considering it has been maintained."
I disagree but you are there and I am not. The compressor simply pushes freon thru the ac system. And the fan is used mainly when the car is stopped. The main cause of overheating when the ac is on is lack of air flow thru the radiator, or coolant thru the radiator.
One thing that comes to mind, you could have a restriction in the cooling passages in the block that is building up over time.
The cooling system has to work twice as hard to cool the engine and overcome the extra heat generated by the condenser. Its also possible you are enduring a power loss on the engine with the extra drag from the compressor. But you should also notice that on hills and under heavy engine load.
I understand and would normally agree. However, what puzzles me is that, below the temp at which the thermostat would normally open, the air movement at 65 mph brings the temperature right down to minimum normal operating but, once the temp goes above where the thermostat would normally open, going 65 mph doesn't seem to bring the temp down at all, not even a little. If there were an obstruction, wouldn't it run at least a little hotter with the a/c off? Turning off the a/c on the fly when the temp is way up at max normal results in a dramatic drop in temp, right down to minimum operating within a minute or so. Were there a significant obstruction, wouldn't recovery be a lot slower?
Since I am not there, I can only use practical experience and theory. The car owner has to do the leg work and testing. You may have to try running the engine with the thermostat out to make sure it is not the problem. You may also have to try other tests to make sure you are not overlooking something. The basic theory is that running the ac puts extra heat in front of the radiator that the engine cooling system has to overcome.
It could be for whatever reason, using a 180 degree thermostat will fix the problem.
Aren't you just treating the symptom? I could disconnect the compressor so it won't run when the defroster is on so I can use it this winter too, but that doesn't solve the problem. Also, who says a 180 degree thermostat would solve the problem when the only time the temp stops rising is when I turn the compressor off? There's no guarantee that buying 10 extra degrees would keep me from overheating as I'm assuming the thermostat is wide open as the temp soars way past 190 degrees. The fact is that in the three months I've had the radiator, thermostat, water pump and related new hoses, the ambient temp has exceeded 95 degrees on numerous occasions while having the a/c on in traffic and, while the temperature builds when standing still, movement of any kind has always lowered the block temp. Now, on a 75 degree day the temp heads for the overheated zone and only turning the compressor off brings the temp back down to the bottom of the normal range. I find it difficult to believe that my a/c is dumping so much heat into the system that it comprises the difference between running at the bottom of the normal range and overheating. I still maintain that any significant blockage that manifests itself as excessive heat would also have an effect when the a/c is off. It would run at least a little hotter. So then, what am I to suspect, my 3 month old cooling system or my 20 year old compressor or fan? They are both the originals. If my cooling system showed other symptoms I would be the first to believe you but you can idle as long as you want on a 95 degree day and as long as the a/c is off, the temp will build to the point where the fan comes on and then drops to the bottom of the normal operating range until the fan shuts off and the cycle begins anew. What bothers me most is that running at 70 mph on a 75 degree day doesn't even lower the temp at all, much less bring it toward the bottom of the normal zone. Incidentally, I can still run with the a/c on without overheating if I don't get caught in stop and go traffic. As soon as I stop and allow the temp to go into the upper normal range and heading toward overheating, I can never get it back down without turning the compressor off. I don't mean to be argumentative. There just seems to be a rush to judgement: If it's overheating it must be the cooling system. I just want to see if an aging fan and aging compressor could be factors somehow. I came here to find out if they could in some way be responsible for the excessive heat. I keep thinking the same thing: without the a/c on, there is no problem.
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SOURCE: temperature gauge is up and down
Sounds like youve noyiced the first sign of a failing thermostat.Its now taking more heat to open the thermostat or its jamming on the slide when it opens and closes.Good luck with it and pay special attention to your temp gauge until its replaced.
SOURCE: after reaching operating temp, longer than it ever
It sounds like the heater core is plugged, It could possibly be the thermostat or water pump. Have you ever had the cooling system serviced? Maybe flush the system and put in a new thermostat with new anti-freeze.
SOURCE: 1994 Lebaron Convertible No Heat, High Temp Gauge
The heat is made in the engine so if the engine is overheated and nothing else is hot, the water is not moving.
I would have suspected a thermostat also.
I would guess now that you have a dead water pump.
Karl at topgunwon.com
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Not sure I responded to the first solution in the propper place. It doesn't seem right adding it to the testimonial section. Just trying to point out that I don't think the cooling system components are the issue. I think it revolves around either the compressor or the fan but I don't know how to check them. The fan turns but fast enough? I don't know.
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