Rep Power: 0

Hi there, wonder if anyone would have a solution for a very cold problem .

My son purchased a used 2000 Civic DX with only 150 km's this summer and it runs great. The problem started with very little heat from the heater when the weather started to plunge.

I flushed the cooling system (twice), replaced the thermostat with an aftermarket one, then soon after with an original Honda thermostat (bled the system thoroughly). The pipes going to the heater core and comming from the heater core seem ok (very hot on both sides), and I also flushed these hoses with water and compressed air to possibly unclogg the heater core. I checked the valve letting fluid through to the heater core (working fine). I felt my way to the heater core thinking that there could be a partial blockage not permitting thorough flow throughout the entire heater core, but it felt very hot all over. I managed to lubricate the louvers directing air to the system and still very little heat.

The water pump seems to be running fine when you rev the engine and have the radiator cap off.

The thing I noticed is that when I check the heat on the hoses going to the heater core when the car is hot at idle (inside the garage), they are very hot. But when I take it for a test drive (cold outside) and check them again, they seem to be only mild in temperature (however, the main pipe going from the engine block to the main rad is very hot). The other thing I noticed ,when driving, is that the two center front panel vents continuously leave in very cold air, while the outside panel vents, floor vents and defrost vents leave in mild air

PLEASE HELP IF YOU CAN !!!

 
Rep Power: 0

Does the blower work on all settings?
If blower runs at all speeds but no hot air comes out the vents, check for the following:
Clogged heater duct
clogged blower outlet
Faulty air mix door
Heater valve cable adjustment
air mix control cable adjustment
Faulty cooling system thermostat
Clogged evaporator (with air cond.)
Frozen evaporator (with air cond.)

Let me know if you need help performing any of the above checks.

 
Rep Power: 227

My best guess would be that the heater core is clogged. Disconnect the heater hoses and flush out the core using the pressure of a garden hose. If that doesn't work, you may need to replace the core, a job that requires removal of the dashboard.

 
Rep Power: 0

Hi DEX, thank for your information.

Sorry I haven't gotten back sooner but I was out of the province for a few weeks.

Could you give me a little insight on how to check if the problem would be a faulty air mix door.

This seems to be one of the last things I haven't checked yet. Is this something I can verify without removing the entire dash assembly, because my next step is going to replace the heater core.

Thanks in advance for the info.

 
Rep Power: 0

Does it smoke out of the exhaust real bad? What's the oil look like when you pull the dipstick...you also have to remember, no heat=blown head gasket, and if it's never been done on that car in the past it's probably about that time. Check for watery oil, check for excess smoke coming from the tail pipe, and has it ever shown to be over heating on the temp gauge? If none of those have happened than you are in luck that it probably is a clogged heater core