heater problems - help!

[ninety6]

My heater only seems (but works fine) to work when the car is moving (engine above idle speed).
1. replaced heater core
2. replaced thermostat
3. Replaced water pump
4. had the system flushed (chemical flush to remove gunky)

any possible way this could be the coolant temp sensor or vaccum line? Coolant just doesn't seem to flow enough when the car is idling to warm the heater core. Even when the car is warm, and has been warm, stopping at a red light often stops the heat (not the AIR, the just WARM air).

Not sure how sensor or vacuum line would be engine speed related, but any suggestions would be appreciated!

Thanks!

[9t8z28]

My heater only seems (but works fine) to work when the car is moving (engine above idle speed).
1. replaced heater core
2. replaced thermostat
3. Replaced water pump
4. had the system flushed (chemical flush to remove gunky)

any possible way this could be the coolant temp sensor or vaccum line? Coolant just doesn't seem to flow enough when the car is idling to warm the heater core. Even when the car is warm, and has been warm, stopping at a red light often stops the heat (not the AIR, the just WARM air).

Not sure how sensor or vacuum line would be engine speed related, but any suggestions would be appreciated!

Thanks!

Not real sure on this one! Check to see if there is an inline valve going to the heater core.

[ninety6]

Not real sure on this one! Check to see if there is an inline valve going to the heater core.

there is. i have thought about replacing it, but that will probably require also replacing a hose... i need to feel the hoses again and see if where its not flowing??

[Danger731]

So the HEAT comes back on if you leave it in neutral and raise the RPM's ?

[9t8z28]

I wound up just replacing it with a plain hose. It worked fine on my 97. If it is blocked, pressure might not even reach the hose.

[ninety6]

So the HEAT comes back on if you leave it in neutral and raise the RPM's ?

yes! you are correct.

[ninety6]

I wound up just replacing it with a plain hose. It worked fine on my 97. If it is blocked, pressure might not even reach the hose.

I have thought about doing that as well... did you just get generic hose, or did they have one custom fit for that application?

[9t8z28]

No. I got heater hose from my work. Generic hose will not tollerate the heat.