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Alright so here's my problem. My 2005 Accord does not have HOT heat coming from the blowers. Sometimes it blows warmish. I just changed my thermostat today, and when I drained my radiator, the reservoir did not empty. The old thermostat looks fine, but I replaced it anyways. I refilled the radiator with antifreeze and let it warm up, and same thing; engine heats up and holds at just under half of the gauge, and blowers blow cold-slightly warm air.

I felt the hoses after it was warmed up and the top is warm, and the bottom is cold. I have a feeling it's the heater core.

Anyone have any other ideas?

Thanks, Josh

  • Which hoses? There will be two interesting sets, the ones to the radiator in the front of the car – with a large (1.5" ish) hoses at the top and bottom, and the ones to the heater. The ones to the heater will be much smaller and much less predictable in their arrangement, but they will probably be close together and run through the firewall. Often the heater core will be in the passenger compartment on the passenger (non-driver) side of the car. – dlu Dec 28 '16 at 0:16
  • It's the two larger hoses; the top connected to the radiator is warm, the bottom connected to the thermostat is cold – Josh Dec 28 '16 at 0:21
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    So, that suggests that the thermostat is closed or that perhaps the water pump isn't working well. Sometimes the impeller in the pump fails and it stops pumping, or slows way down. See if you can find the hoses to the heater core. They will be about the 3/4" to 1" in diameter and look kind of like the radiator hoses. They will probably head towards the firewall. They are on the "other side" of the thermostat and should be hot even if the thermostat hasn't opened yet. – dlu Dec 28 '16 at 0:24
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No heat or not much heat can be the result of 3 things - bad heater core valve, partially clogged heater core, or a bad water pump.

Bad Heater Core Valve Drain the coolant system. Remove the hoses from the valve. Change the temperature slider in the car and watch that the valve opens / closes so the coolant can flow through to the heater core.

Partially Clogged Heater Core
Drain the coolant system. Remove the heater core hoses. Do not remove them at the heater core, if you break the heater core, you will have a bad time. Flush water through both ways. If it seems to flow good, you are fine. If it doesn't flow well, there might be a clog. Pushing water through backwards helps remove dirt and rust that may be stuck in there.

Bad Water Pump
Bad water pump is usually also accompanied by overheating. The impellers can wear down or break and not rotate with the shaft. This will lead to flowing less coolant than necessary.

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