I really need help. I have an 05 Civic LX, just the basic commuting car for me. My problem is, it overheats when the air conditioner is NOT on. If I driver with the heater on in the morning or mothing on at all, the temp rises fast. when the AC is turned on the temp drops. I took it into Honda in my area and I was told its the head gasket. I'm not new to mechanics but forein cars are new to me. I dont have water in the oil and I havent seen any water out of the tail pipe. Is this commen for a Honda head gasket or was the dealership tryin to pull a fast one? Please help.

 

welcome to the forum: check to see if your primary fan comes on when the temp gets to about 3/4 high. the rad is cooled when the a/c fan goes on and not before due to the fan motor dc motor does burn out,or it can be the thermal switch. Yours seems unsual to go out so soon. check these before doing head work.

 

that is very possible, it could just be a thermostat in my civic the stock thermostat opened up too cold so i had the problem just like you. check it sometimes they are faulty. im going out on a limb here but could freeze plugs be a problem???