My car heater heats a little, but never gets really very warm anymore on my 98 Camry 4 cyl. The temp guage usually gets just a little bit above the Cold mark at the bottom--it never gets to the middle or to the warm/hot stage. Is this a thermostat problem?

this may be a goofy question BUT do you mean flushed the radiator not the heater core. Heater core is on the firewall.
Check the hoses going into the heater core to be sure they are both hot after the car has reached running temp. This will let you know if you have a blocked heater core not radiator.
Just wondering?

The slow rising temp gauge points to a thermostat which has failed and stuck open. This is easy to replace.

At the same time the gauge will tell you if the car is overheating.

Is it losing coolant at all? A hot smell can result from leaking coolant getting on the exhaust manifold.

The smell can also result when leaking engine oil gets onto the exhaust. Camrys of that era had several characteristic oil leaks

- from the rear of the cam cover, especially on a V6
-from the distributor shaft o-ring
-from the oil filter-to-engine block mounting adapter (if fitted)

Your radiator cooling fan will only come on when the engine temp has reached the point where it needs to have air forced through the radiator and thus bring engine heat back down to safe operating range. If your heater is not working check to make sure the fresh air vents aren't stuck open (are the controls stiff or not going all the way across?) check also that the heater shutoff valve lever which is usually situated on the firewall at the rear of the engine and can be found easily by tracing the hoses back from the thermostat housing aren't bent and/or seized up.

Just saw your second posting, so the temp is still above normal. Could the sensor
that controls the fan be not reading the heat properly ? The antifreeze/coolant
issue could still be relevant, so I will re-post that info. Tho.
Electric cooling fans will sometimes come on after a vehicle is parked,
(It actually heats up when stopped), but not when it is rolling down the road
because the movement is applying some cooling effect to the engine.
\
If the engine is not actually overheating, then the fans may be working
normally. Also, make sure your water/antifreeze mix is correct by using a
specific gravity tester. It is a tube with 4 or 5 balls, some of which will float
to give you a reading. Contrary to popular belief, More is not better when it
comes to antifreeze/coolant. It needs water to work properly. Too strong a
mix will actually make your vehicle run cold so that the temp sensors and
heater will not function properly. The engine will not achieve proper operating
temperature and may actually damage some of the components by running
it cold, affect timing, spark, etc. This could also cause the symptoms you
describe. The engine would not actually reach the proper heat threshold
until you added the extra demand of the AC heat transfer. But the first criteria
would be whether the engine is actually overheating / or in normal range .
It may be that the colder weather is allowing the sensors to come on a little
later, warming the engine and heater components a bit more than they would
in warmer weather. Would be good to know what the actual coolant temp is.
Could check that with a guage, and also check to see what temp thermostat
you are using. 195 degrees in the winter would be better, 165/180 or so in the
warmer months

It is much more likely you are low on coolant or you have an air bubble trapped in the cooling system. You should bleed the cooling system to get any trapped air out and make sure it is full of coolant.

Have your husband look for this heater control valve along the heater hoses. It is connected to the temp cable and should open fully when the control is set to hot. It may be disconnected or clogged.

P0125- Engine not reaching operation temp quick enough. Possible problems:

• Insufficient warm up time
• Low engine coolant level
• Leaking or stuck open thermostat
• Faulty coolant temp sensor
• P1130- A/F Sensor Circuit Range/performance, Bank 1 Sensor 1

If the hoses to and from the heater core are hot , and you say the heater core is hot , then the only answer is that the air duct that flows into or out of the heater core plenum ( housing ) is not opening.
Heater control on dash borad inoperative.
Not sure about 92 capri , some cars have a cable linkage , some work on vacume motors.
Try to find a haynes manual for your car , they will walk you through almost every step of anything you may ever want to do to your car.

You seem to know what you are doing , but I gotta ask ........the heater core you felt was up behind the dash inside the passenger compartment of the car right ?

sounds like a faulty thermostat if not that plugged heater core.

Have you felt the hoses going to the heater core ?

Your heater core may be bad also.