My 1994 Chrysler Concord overheats if the car interior heater is turned off.

Question

My 1994 Concord has 256,000 K's on it and the air conditioner does not work. I received an estimate to have the air conditioner replaced but opted to roll down the windows instead. My big problem now is that the car overheats unless I turn the interior heating system on. When the interior heater is turned on (set to Auto but temperature setting does not seem to matter) the engine temperature is stable. Soon after turning the heater off, the engine temperature shoots right up. So not only do I have no air conditioning, I must have the interior heater turned on, soooo, when it is hot outside it is even hotter inside.

Answer 1

Try this first!

Open the hood, and look between the radiator and A/C condenser (mounted in front of radiator) and check the front of the condenser, too. Make sure there's no leaves or other stuff crammed in there blocking the air flow, clean out anything that's in there. It's free and easy, and is often overlooked.

If that's all good, or you clean it and it continues overheating, then check to make sure one of the radiator fans is turning on. It should come on when it reaches a certain temperature. If it doesn't come on, it could be a coolant temperature sensor/switch, relay, or the fan motor itself gone bad. May need to take it to your mechanic to have them check which is causing the problem if you don't know how to.

If the fan comes on like it should, then go ahead and replace the thermostat if it hasn't been changed recently, it's fairly cheap and easy to do.

If it still overheats after that, then it is something blocking the flow internally. First thing to try then is flushing out the system. If that doesn't work, it might need a radiator, or other work. Again, might consider taking it somewhere to have it checked out instead of throwing parts at it if you get this far.  

Answer 2

Check the thermostat. It's a small inexpensive module, $15 to $20 - maybe even cheaper, installed in line with the output from the radiator. It controls coolant flow to your engine based on conditions. It sometimes sticks and needs replacement. Any auto parts store counter jockey can easily sell you the part and show you exactly where it's located  on your car. Try a Murray's or Auto Zone, their counter jocks will come out to your car and show you what to do.  I would suggest you go buy a Chilton's auto repair manual for your car too. It's cheap and  could save you thousands of dollars in the long run. Good luck and I had a old Chrysler and drove it for over 325k... so you can keep it on the road with alittle TLC. OH and do what Barack says... check  the air in your tires if you want to save the planet.

Answer 3

You have some sort of problem with the cooling system, but I can't see it from here, so you'll have to take it to your mechanic and find out what it is and get it fixed.

Answer 4

it could be as minor as a thermostat, or it could be a relay causing your electric cooling fan not to come on by the radiator, but with that many miles it is possible that the radiator is starting to clog up.  

Answer 5

its time to check the radiator,. thermostat  and head gaskets.   usually if you car is only cooling off when the heater is on, the radiator is not doing its job... even the water pump should be checked.  with that many miles on it it could be all of the things i've mentioned.  rarley you can have a collaped lower radiator hose too. over time they get hard or soft and either  break up or collapse and wont let the water thru or just dump it out on the ground.  you'de have seen that much water . my bet--its the radiator and then head gaskets. not uncommon with the miles on this one. you've gone alot further than most..  good luck with it.

Answer 6

have the radiator flush out or diped at a radiator shop... id first check the fluids in the radiator and jug check your belt or fan... but id bet its just needs a cleanning out

Answer 7

Dude you have what's termed as a volume problem with the the cooling system. The radiator is partialy plugged. It isn't allowing enough coolant flow to adequeatelt cool the engine. When you turn on the heater, you are actually ussing it to pull heat out of the coolant. replace the radiator and thermostat. You should be fine then.