Hi all! New to the forum, but you guys have been a WEALTH of information getting my car running.

First, a little background. I picked up a 1996 Accord LX on its last legs for $400 (literally saved it from being junked, they were going to junk it for $350). It idled super rough, had extreme hesitation and stalling problems, and overall ran pretty crappy. Over the course of two months, I have been fixing it up, with it finally running again last week. I did the timing belt, water pump (OEM Honda), balancer belt, had the cylinder head cleaned, checked, and rebuilt, had the block tested for flatness, and did the head gasket. I also replaced all four injectors with new ones from Honda, all new spark plugs+wires, new distributor cap and rotor, new ECT, new temp sender, new OEM Honda radiator cap, and changed the thermostat with one picked up from auto zone. The car has all fresh fluids in it, and starts up and runs like new again. EXCEPT
for the following issue, which I'm posting for.

The cooling system is inconsistent. It has been running hotter than it should, but not quite overheating. I have double and triple checked for air in the cooling system using both the bleeder method and the funnel method, and the radiator fan comes on and goes off when it should. I don't see any leaks under the car (other than a heater hose that drips maybe three drops of coolant after shutting the car off) and the coolant level is steady in both the radiator and overflow. It concerns me, as the weather here is fairly nice this time of year (~70-75 during the day, ~65 at night) and I worry that the car may overheat come summer. The heat comes through nice and hot. The only thing I have noticed is that the condenser fan will not come on when the AC is on, but will run when the radiator fan comes on at idle (figure B below)

I did an experiment tonight to see what goes on under different driving conditions. With the heat on full blast the entire time, I drove it for 20 minutes around the city (after letting it warm up for 10mins), the heat blew out nice and hot the whole time (see Figure A below). Then, I drove it for 20 minutes on the highway at a steady 80mph, the temp gauge rose and the heat became lukewarm (see figure C). After that, I got off the highway and drove it home on back roads and the heat became nice and hot again and the gauge dropped back to normal. At idle, the temp rises to halfway and then goes up a bit, then drops down after the fans come on (see figure B.)



I can't for the life of me figure out what is causing this, but it is frustrating and taking away a bit of the excitement of having the car running so well!
Here is a shot of the car before I washed it , shortly after we got it running again.



And the motor



Get back to me if you guys have any ideas! I'm stumped.


TL;DR: Temp gauge inconsistent, see picture of temp gauge.

 

Have u noticed any swelling in ur radiator hoses , I had a V6 that one of the heads had a slight gasket leak that went into the coolant kind of did what ur gauges are doing. I could not idle for more than 5 min without the temp rising and in town driving the temp was normal but my highway driving temp was the same as the idling temp around 3/4 of the way on the guage

 

Also, make sure the fans are spinning the correct way, they should be blowing air on the engine not on the radiator. And verify that the car is actually overheating using a temp gun at the sending unit, eliminating gauge cluster problems, anything over Half is overheating.