5.0L General DiscussionThis section is for non-tech specific information pertaining to 5.0L Mustangs.
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i have a 95 gt and every time I turn the a/c on it over heats. Idk what else to do i have replaced the water pump, replaced the upper, lower, and bypass hose no thermostat, new thermostat housing, cleaned the cooling system, high speed fan, its a new/rebuilt a/c compressor i have the condenser and the lines sitting in my apartment. It has Lincoln heads with the heart shaped combustion chamber, a mild cam 1/2 intake riser msd distributor, cap, rotor, ford racing wires, high flow oil pump and prob some other things i just cant remember right now but any info helps thanks!
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Only a small portion of the thermostat actually opens. That is an engineering design, for a reason. The water pump will push the coolant through the system too quickly if you don't create an intentional restriction. This is a very common problem that people in the south experience after they remove their thermostat, and they always argue the point.
The only other component you haven't replaced is the radiator. You could take it out and test flow.
Also, how close is your A/C compressor to the temp sender ? Engaging the compressor creates ambient heat, maybe your sensor is being affected by it.
With out a thermostat the coolant is not in the radiator long enough to release the heat of the engine , while at the same time its not in the engine long enough to effectively pull the heat from the block. Turning the ac on is just the straw that broke the camels back.
Ok op so Im sifting through your original post and it says you have the a/c compressor on the car , while the lines and condenser are in your apartment. So essentially your running dry pump, with no lines ,no condenser, and no refrigerant ?
Your a/c compressor clutch should not even engage if you have 0 pressure in the system. the high pressure switch wouldnt allow the clutch to engage .
What exactly do you consider to be over heated my 94 will climb up to 220 on the temp gauge in the summer time while idle and it is normally right about 200 cruising at 65.
The 195 you mention it not falling below, is that with the thermostat or with out? 195 is the rated temp at which the stock thermostat is set to start opening. With out one the coolant will continue to soak up heat from the engine with no time in the radiator to dissipate that heat. You have to have a thermostat to start to diagnose the problem. You put the thermostat in make sure you have the system free of any trapped air, assure you have no external leaks. Now if it still over heats you can look else where. Are you loosing coolant ? Lost coolant is replaced by air , air in the system kills the effectiveness of a pressure reliant system. Air in the system takes up space it doesn't allow the system to build the needed pressure to keep the coolant from boiling in side the system. Boiling leads to steam and steam escapes.
Now look at flow , if the radiator has been subjected over the years to a lot of well water or highly mineralized water it will start to collect in the radiator, especially calcium and iron, it will collect in the bottom corner of the radiator, this will substantially lessen the surface area that the coolant has to travel through the radiator. Once enough mineral builds up you can loose almost a fourth of the cooling capacity . No amount of radiator flush is going to remove this calcification from the system. With the engine up to temp shut it off and feel the surface of the radiator if you find any cold or cooler spots than the rest its because there is no coolant flow to that portion.
What is your timing set at? Over advancing the timing will cause the engine to over heat. Any white smoke or steam coming out of the exhaust? Blown head gasket ? Cracked head ? warped head? If you are constantly having to add coolant yet there are no visible signs of external leaks the coolant is going someplace, Its either out the exhaust or in the oil.
You have some home work to do here yet. You will find the members of this forum group can be a great help when it comes to diagnosing a symptom , however when a problem arises and you don't have the system functioning as it was intended to by the manufacturer, the first responses will be to get it up to spec , then work from there.
ok maybe i should just rephrase the question. my car does not normally over heat normally without the thermostat in it it runs at almost 150. the only time it ever gets passed that is when i turn the ac on. I have replaced the head gaskets but im not loosing any coolant, im not burning anything there is no kind of smoke i have already double checked the timing there are no leaks yes i have physically taken the radiator out and had it tested. the thermostat does not help in this situation regardless if it is in the car or not. everything everyone has mentioned is very good answers in a car that regularly over heats but like i said it only over heats when the A/C is on and blowing cold
Ok so lets see , does the fan kick on like it should when you turn the a/c on??? The fan should run continuous when the a/c is on.
the fan is on a switch that i control inside the car so yes it is always on.
the only thing that i have not checked is if there is a clog in the condenser or ac lines idk how i would even go about doing that. Everything else is in perfect working order the a/c clutch kicks on when it is suppose to, the fan i control which is on soon as i start the car. The pressure inside the system is fine i had that checked. I have a new condenser and line's for it just have not put them on yet. If the a/c system is low on pag oil would it over heat the car?
I would think that where ever you had the compressor hooked up would have found anything blocking the system when they put the gauges on it and pulled the system down under vacuum to charge it. Also they would have added every thing to the system it needed to function properly. I cant imagine that if the air blows cold that there is a problem with the a/c system. Now if the condenser is full of bugs or other road debris and its blocking the flow of air through the radiator that would cause it to over heat. A bad compressor if its binding up will cause overheating as well . Possible you got a bad rebuild?
99% of the time when the ac causes over heating its a sub par cooling system . There is something in your cooling system that is not functioning correctly.
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