98 Honda Accord EX 4CYL - Thermostat Gauge all over the place.
 

For a couple years my thermostat would stay on cold, actually it looked more like to dropped to the bottom, and then it would go to normal if I tapped on it with my finger.

Now my thermostat is doing the opposite, it climbs to hot, and drops to normal.

I'm not sure if it's actually overheating or just a problem with the gauge?

I verified the (2) cooling fans come on when I initiate the AC, but the fan do not come on after driving for a while and then becoming idle. I parked the car and verified the fans were not coming on.

The water reserve for the radiator is fine, and my radiator is also full, so any help would be great.

Regards,

--tj

You really should have fixed the temperature gauge when it started, because it is there to warn you of overheating. An overheating engine can get damaged and be a very expensive repair. I'll get off of my soap box now!

The thermostat gauge is a separate circuit to the temperature sensor controlling the fans. You are dealing with two problems.

The temperature sending unit controls the gauge in your car. It is one of the sensors under the distributor on the cylinder head. It is the closest sensor to where the upper radiator hose connects to the engine and has one wire going to it (#14 in picture below). Unplug the wire and see if the temperature gauge stays at cold when you turn the key to the II position. Touch that wire to ground (use a valve cover bolt), turn the key to the II position and see if the gauge starts rising to H (turn off key when you get close to H).

The Thermo Switch is likely the problem of why the fans are not turning on, since the electronics (relays, fuses, ground, etc..) of both fans work. #15 in the picture.

http://www.hondapartsnow.com/diagram...sor-456776.png

Most of the time tapping on the dash board moves the needle to the correct spot.

Then something is likely up with the gauge in the car. You can buy the temperature gauge at a junkyard, Ebay, or a new one at the dealership.

You can remove the instrument cluster and replace the temperature/fuel gauge.