My 1994 heater just blows out ambient temperature air. I have tried power flushing the radiator, which fixed the problem up until I let the car sit for a couple of months, now the heater is just blowing ambient temperature air again. Someone suggested that I do a reverse power flush on the heater core, but after looking under the hood, that does not seem possible... Thoughts?

It could be as simple as an air lock, or low coolant. First, make sure the overflow bottle shows coolant up to the cold line..(assuming you start this with the engine cold)..then remove the radiator cap, start engine and let it warm up until the thermostate is open...then have someone inside car keep the RPM's up around 1500 to 2000 and with the engine running at that speed, fill the radiator as full as you can get it, then install the radiator cap.
If your lucky, that might be all it is. If that does not work, try "feeling" of the incoming and outgoing heater hose, both should feel hot, if not, then there could be a restriction somewhere.

Thanks for your insight. It's actually turned out to be the heater core that is plugged beyond repair. I ended up taking it to a mechanic who also tried flushing out the heater core without any luck. My '94 is a convertible and does not have a glove compartment so I think that makes the removal and replacement of the heater core 'extra special'... This is why I've named my Vette 'Hal' after '2001, A Space Odyssey'... He's as ornery as Hal... :thud:

It could be as simple as an air lock, or low coolant. First, make sure the overflow bottle shows coolant up to the cold line..(assuming you start this with the engine cold)..then remove the radiator cap, start engine and let it warm up until the thermostate is open...then have someone inside car keep the RPM's up around 1500 to 2000 and with the engine running at that speed, fill the radiator as full as you can get it, then install the radiator cap.
If your lucky, that might be all it is. If that does not work, try "feeling" of the incoming and outgoing heater hose, both should feel hot, if not, then there could be a restriction somewhere.

:iagree:

Where are you that you need to use your heat?

Where are you that you need to use your heat?
I'm in Santa Cruz, California which is on the coast about 150 miles south of San Francisco. In the summer we often have temperatures that don't exceed 68 and the fog doesn't burn off until noon... Besides, being a woman, I'm always cold... ;)

I can relate to that 1

I can relate to that !