Rep Power: 0

Hey guys, I have a 98 civic dx hb, 5speed, stock engine, 230k miles.

the car runs great, heat works great, and the ac blows cold.

while driving with the ac on for a while, the temp gauge will start climbing, after about a half hour.

when it does this, I turn the ac off, open the heater core, and the temp goes back to normal.

The radiator fan comes on when the thermostat switch calls for it, and the condenser fan comes on when I turn on the ac.

should both of these fans run while the ac is on?

 
Rep Power: 224

Condenser and radiator fins clean and clear? Both fans should be on when A/C is engaged.

 
Rep Power: 0

yes, fins are all clean and clear.

I’ve never seen both fans run with my ac, which would explain why it always heats up while running.

I’ll look into why it’s not working properly.

any ideas on where to start?

 
Rep Power: 224

Fuses and relays are always the best place to start. I'm not real familiar with the 6th gens so someone else may have to chime in. The service manual is available here:

https://www.civicforums.com/forums/1...nual-free.html

 
Rep Power: 518

The 2 radiator fans are controlled independently of each other.
Since the radiator and condenser are mounted side by side:
The fan for the radiator only operates when the engine needs it.
The fan for the ac condenser should only operate in tandem with the compressor clutch.

I didn't read so I better ask
Is the radiator completely full of liquid? (not just the overflow bottle) They do blow head gaskets. .
Fan blade spins in the correct direction? (blow air toward engine compartment)
I might use a garden hose and sprayer to clean radiator fins, make sure to spray from rear to front though.
While the radiator cap is off, use a light and check for corrosion such as lime/calcium deposits inside the visible tiny radiator tubes. (hard water deposits)
A failing thermostat...maybe not first guess but is cheap lol

 
Rep Power: 518

There is a ground cable that runs from the chassis (probably bolted to body metal or engine mount area), to a valve cover bolt or directly to the head. (I've seen so many variations I don't remember specifics of individual years and models)

I've read if that cable has a problem it could affect the temperature gauge electrically

 
Rep Power: 0

the radiator is new, new radiator cap, new thermostat, fans spin correctly.

i ran the car with ac today, and had zero issues.

seems to be an intermittent problem.

 
Rep Power: 0

I’ll definitely check in to that, thanks!

 
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Ok guys, my car overheated again today, while running the ac.

Also, every time I put gas in the car, it acts like it’s overheating (the temp needle goes to about 3/4 before I pull over and shut the car off) I’ll sit there for about 10 minutes, crank the car, needles back at 1/2 mark, and runs fine the rest of the time. Weird.

there’s no steam from the tail pipe, no milky oil (I adjusted the valves today, so I saw a good bit of the oil), coolant hoses all have good pressure, no visible leaks anywhere. But every few times I drive the car, I have to add coolant to the reservoir.

I also did a compression test today, these are the numbers I got;Cylinder 1-187

Cylinder 2-178

Cylinder 3-172

Cylinder 4-170

any info would be much appreciated!

 
Rep Power: 224

If radiator and reservoir are both continually going low that points to a leak.

 
Rep Power: 0

if that’s the case, would the system build, and hold pressure?

 
Rep Power: 0

Just an update, last week I did a combustion leak detection test, and the car failed.

I replaced the head gasket, and noticed the coolant thermostat switch was broken, and heater bypass hose was soft, and deteriorating.

I ordered a new hose, and coolant thermostat switch.

I did another combustion leak detection test (for peace of mind), now the car runs great, and I can enjoy a/c once again