1998 Honda Civic Overheating when running A/C or cool outsi

Tiny
HJ3
  • MEMBER
  • 1998 HONDA CIVIC
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 143,930 MILES
1998 Honda Civic LX, 143,930 Miles Auto trans front wheel drive.

Whenever I turn on the a/c, turn the temperature selector switch to blue and/ or run outside air while the temperature control switch is in blue, the engine starts to get hotter and the temperature gauge will steadily increase to hot from being in the middle.

Whenever I turn on the heater or keep the temperature control knob in the red without running the heater, the cooling system functions normally.

I've tried replacing thermostats, bleeding air from the cooling system, replacing the radiator and radiator fan. The condenser fan comes on when I turn on the a/c. I noticed when I was bleeding air from the cooling system, that when I turned on the a/c or turned the temperature control knob to blue, the coolant rushed to the front (radiator filler neck) and continously bubbled out - it was as if vacuum was pulling the coolant to the front, away from the engine. When I turned the a/c off and put the temperature control knob in the red, it bubbled normally letting out the air pockets.

What could be potential problems? Could it be a mismatched hose/s? Bad sensors or relays? Some other electrical issue? Any help would be appreciated. Thanks!
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Saturday, August 7th, 2010 AT 11:37 PM

15 Replies

Tiny
KHLOW2008
  • EXPERT
Hi hj3,

Does the radiator fan comes on when the A/C is turned ON?

When engine is cold, is the coolant level in radiator correct?
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Monday, August 9th, 2010 AT 2:15 PM
Tiny
HJ3
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In reply to:

Does the radiator fan comes on when the A/C is turned ON?

When engine is cold, is the coolant level in radiator correct?

That's something I have to confirm but I'm pretty sure both fans operate when I turn on the A/C - matter of fact, the radiator fan is new.

The coolant level in the radiator is correct. I bled the system and ensured it was filled to capacity.
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Tuesday, August 10th, 2010 AT 7:50 AM
Tiny
KHLOW2008
  • EXPERT
Ensure both cooling fans are working when A/C is turned ON. As radiator fan was just replaced, check if the fan baldes are turning in the correct direction. Some motors would have the direction reversed if you follow the wire color code.

Ensure that there are no blockage of the radiator and condenser cooling fins to restrict air flow.

Run engine till temperature reading increases and note if the coolant is bubbling out to the recovery tank.

Feel the air being blown into the engine compartment to see if they are hot.

Check if the lower radiator hose is hot or much cooler than the upper hose.

To ensure the engine is really overheating and not just an error on the temperature gauge reading, get a temperature reader and get the reading at various part of the engine.
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Tuesday, August 10th, 2010 AT 8:10 AM
Tiny
HJ3
  • MEMBER
I checked it out over the weekend. Both cooling fans are coming on and the blades are rotating in the proper direction.

As far as I can tell, there's no blockage at the radiator or condenser fins, but to be able to get a better look, perhaps I should take them out?

Coolant does go to the recovery tank, however, in order to see what happens, I put in my no spill funnel again and ran the a/c with the temp. Selection switch in blue (cool), and then ran outside air with my temp. Selection switch in blue (cool). At both times, after some running, the coolant began to boil wildly from the funnel, and the level was rising within the funnel, whereas if I had the temp. Selection switch in red (hot) and had the a/c off, the bubbling wouldn't be as wild and the level wouldn't rise. It's like I was pulling a vacuum on the fluid making it rise, but I wasn't.

I have to feel the air again because it was hot underhood as expected, although the air from the fans wasn't as hot as the engine compartment - but we had some hot days out where I live so I have to wait until it cools down in order to feel the incoming air.

The lower hose is way cooler than the upper hose. The upper hose is hot to the touch whereas the lower hose, I could relax my hand on all day.

I have to purchase a reader.

Thank you very much!
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Monday, August 16th, 2010 AT 9:31 AM
Tiny
KHLOW2008
  • EXPERT
Recheck the thermostat. Seems it is not working correctly.
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Monday, August 16th, 2010 AT 9:57 AM
Tiny
HJ3
  • MEMBER
Ok will do - quick question -

I've changed the thermostat about 3-4 times now. The first 2 times I got a thermostat that was higher temperature, then I learned to go with the OEM spec thermostat. Is this a case where I may have to get my thermostat from the dealer rather than my local autoparts store because they don't seem to work? Thanks!
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Monday, August 16th, 2010 AT 10:09 AM
Tiny
KHLOW2008
  • EXPERT
It is better to use oem parts.

Remove the thermostat and test if the overheating occurs. Ensure the coolant flow is fast to eliminate the possiblity of weak water pump.
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Monday, August 16th, 2010 AT 10:33 AM
Tiny
AXIS
  • MEMBER
Try running the engine without the thermostatic valve. Be sure to install the rubber surrounding the valve which serves as your gasket. If the overheating stops, check for the coolant pressure in the system. If pressure is good, check for restriction. If pressure is low, check the water pump.
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Monday, August 16th, 2010 AT 10:45 AM
Tiny
HJ3
  • MEMBER
I ran the system with the thermostat removed. There was no overheating and when I finished driving, the lower radiator hose was a lot hotter than usual (usually it's warm enough to grab). I'm leaning towards there being a restriction somewhere in the cooling system. I was going to buy all new hoses for my cooling system, and do a flush and refill. Does this seem like the proper course of action? What do you think about the flush/cleaners that you mix in before doing the flush or would you recommend flushing the system out just with water? Thanks!
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Monday, August 30th, 2010 AT 11:59 AM
Tiny
AXIS
  • MEMBER
Most probably you have a water pump problem.your thermostat was changed several times, however the pressure of the pump in not enough to open the thermostat fully. when whas the last time it was changed? before you replace more parts,have it checked,replace if the blades are badly corroded.


http://www.2carpros.com/forum/automotive_pictures/557695_Photo0034_1.jpg

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Monday, August 30th, 2010 AT 2:45 PM
Tiny
AXIS
  • MEMBER
Before you spend more, have the water pump tested/checked.
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Monday, August 30th, 2010 AT 4:39 PM
Tiny
HJ3
  • MEMBER
I changed the water pump in the middle of june of this year. Before that, the water pump that was in the car was the original water pump and finally died. The problem existed though before that water pump died. When I replaced the water pump, I also replaced the timing belt, tensioner, and pulley belts. I replaced the original water pump with a gmb water pump and a contitech timing belt. Thanks!
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Tuesday, August 31st, 2010 AT 12:47 AM
Tiny
KHLOW2008
  • EXPERT
The thermostat is faulty. Check the rating and installation. After installation, the system must be bled correctly and if air is trapped in system, it can cause premature damage to the thermostat.

The other reason for the overheating would be a bad head gasket. This would cause pressure to build up in system and coolant would be expelled from system resulting in air pockets. When overheating occurs, wait for engine to cool down and check level in radiatos.
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Tuesday, August 31st, 2010 AT 4:35 AM
Tiny
HJ3
  • MEMBER
Hello all: I finally got aroudn to changing out all my cooling system hoses and doing a complete flush and refill on the system, as well as install a new thermostat to factory spec (unfortunately I wasn't able to get an oem thermostat but I didn't skimp on the costs and got the best one possible that had the oem specs). When I removed the water bypass hose, I found the cause of my problem. The passage to the thermostat housing was blocked. The old hose was also blocked up the midpoint of the hose where it bended. I had to drill the blockage out and clean out the chamber on the thermostat hosuing and when I looked in the hose, it appeared to be putty. Now, I never used radiator stop leak nor put anything detrimental into my cooling system however, I did have a fallout with a tech. In the past who could've done it, although I'm not blaming him for it. It was a funny thing to see though and I didn't get furious over it - if anything, I got kind of mad at myself because when I was squeezing the hoses to check for blockages, I squeezed this hose countless times and never felt any resistance but when I took it off, the material inside was solid. Nevertheless, that was the cause. I put on new silicone hoses with the original stock spring clamps (any opinions with this setup). So far so good - I'll try the ac and outside air later but I'm betting that this was the cause. Thank you very much for all your help and have a good day!
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Sunday, December 5th, 2010 AT 8:23 PM
Tiny
KHLOW2008
  • EXPERT
Glad to know you have fixed the problem. Clogging is one of the factors for inefficient cooling as it is not recirculating correctly.

Using the OEM spring clip is the best way to go about as spring clips would tend to last and provide better sealing over time. They would provide constant pressure on the hoses but if the joints are not good with signs of corrosion, aplication of sealant is recommended.
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Monday, December 6th, 2010 AT 7:05 PM

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