Heater switch?
 

Stock 96 Civic

Previous owner ran no thermostat and water in radiator - after radiator exploded from being frozen, I replaced the radiator, thermostat, upper/lower hose, bypass hose.

Car warms up, but no heat. After about 5-10mins of driving the car temp climbs very slowly all the way into the red. If the heater is actually turned on, there are times where heat will actually blow out.

Turning on the heat doesn't always bring the engine temp down, but the heat never works unless the engine temp gets hot. and even when it does, it won't stay on for very long...

Any ideas? I'm thinking maybe the heater switch?

Re: Heater switch?
 

If the radiator exploded when it froze did you check out the engine? Usually that results in a cracked block as well.

If the engine is fine then it's either you need to bleed the air out of the cooling system or your water pump is shot. There's usually a 'weep' hole at the bottom of your water pump at will have coolant flowing out to alert you to the fact the water pump isn't work.

Running no coolant in an engine is a really bad idea there could be losts of damage because of that. If you pin to the top of your temp gauge it's very like the head has gotten warped as well.

hope this helps.

Re: Heater switch?
 

Ok. I'll check that weep hole ASAP. The engine has an idle problem as well but that was happening before the rad blew up.

The previous owner abused the hell out this little car so it wouldn't surprise me if the head/block is fried.

Thanks for the info!

Re: Heater switch?
 

If your heat doesn't blow hot and the engine coolant temp doesn't dip when you turn the heater on, check your heater control valve located on the firewall behind the transmission. Yours might be stuck in the cold/closed position. Silly question, but did you replace the radiator cap? It might be keeping too much pressure on the cooling system.

Re: Heater switch?
 

how about check the thermostat
and the coolant temp switch sensor

Re: Heater switch?
 

Thanks for the help all!

Turns out I didn't have the upper hose clamp tightened enough. Anti-freeze blew out after engine heated up.

Stupid mistake on my part! Been too long since I turned my own wrench.