I have a 98 Honda Civic LX automatic. Yesterday, the temp gauge started going up to H while idling and back road driving. But on the highway, it was normal going like 55 or more. It only goes up when driving slower speeds or idling! I am sure I have coolant in both radiator and backup reservoir. I was also told my a/c compressor is wired to my fan?! And that's not correct so I was told a/c on while idling will cause gauge to go up. But a/c while driving keeps it in the middle. Now, I keep the a/c off completely and the car temp gauge still goes all the way up when driving slow/ med speeds and idling. I have read it could be the fan, or an air pocket in system or failed water pump. With my description, what do the pro's think? Even with a/c turned on while driving slow, the temp gauge goes up to H.

 

Unlike most cars, on the 1992-2000 Civics the radiator fan and A/C condenser are completely separate and each has its own dedicated fan. It sounds like the radiator fan is not working. That will cause overheating when the car is not moving. The fan is activated by a thermal switch at the thermostat housing, where the lower radiator hose meets the engine. Unplug switch and jumper the pins in the plug on the car side. The fan should now start immediately when you turn the key on. If it does not run, troubleshoot the motor, fuse, and relay. If the fan does run, test drive with it running all the time and confirm no overheating. No overheating with the switch jumpered means the switch is bad, replace it.

 

Even if it over heats going slow/ med speeds as well?

 

Guys, I was told to crank up the heat in the car. But when I turn the fan on and blast the heater, the car only blows cool air even when I have the dial all the way toward heat. And the temp gauge still goes all the way up :-(. Won't b able to see a mechanic till tomorrow or Wednesday. Any1 have an idea why my car won't blow out heat to alleviate under the hood??

 

First off, did you do what I said to force the radiator fan to stay on all the time?

Heater blowing cold means there is a bubble of air in the top of the engine preventing flow to the heater. You need to refill the system through the radiator:

Park on level ground or facing uphill (so the radiator is the highest point) and wait until the engine is COLD.
Remove radiator cap and fill the radiator with coolant to the top.
Set the heater dial or slider on full hot.
Start the engine with the cap off. Add coolant to the radiator as needed to keep it full to the top.
When the engine is warm, put the cap on. Make sure there is coolant in the reservoir tank as well.
You should now have hot air coming out of the heater. Stop the engine and wait until it is cold and check the radiator again. Repeat the whole process if it is not still full to the top.

DO NOT keep driving overheated, or with coolant so low that the heater does not work. Severe engine damage is likely.

 

mk, thank you. I'm a single woman divorced and my X moved away with all tools. I also know nothing of mechanics. So I can't do the jumper trick you mentioned :-(

The reservoir tank is filled with coolant. Not sure about radiator. I'll park it on a slight incline and do as you've suggested. When I remove the radiator cap, should I see coolant looking down it?

Would a bubble of air in the top of the engine cause overheating? It messes with the coolant flow?

 

Yes, the radiator and engine have to be completely full of coolant, not air, to work properly.

Jumpering the switch you just need a small piece of wire, almost any kind of wire, or an unbent paper clip to do.