I have a question on my '96 Civic DX.

Here lately I've noticed it running warm every once in a while and the heater has started to blow cold air occasionally. Is this the thermostat messing up or possibly the heater core having issues? Help needed, thanks for any suggestions.

 

There are a few possibilities.

First, you may be low on coolant. Make sure you have enough coolant in your radiator and bleed the coolant system to remove any air bubbles that exist.

Second, your thermostat may be failing. It's easy to replace but you'll need to drain the coolant first.

There are DIYs for both of those in the Routine Maintenance DIY section.

 

Those are classic symptoms of being low on coolant. With the engine cold, take off the radiator cap and make sure the radiator itself is full to the top. If not, refill it and find out where you are losing the coolant.

Don't just check level in the plastic tank, it is important to check the radiator too.

 

thanks for the suggestions, I'll check the radiator fluid and if it's not the problem, I'll go ahead and change the thermostat.