Intermittent Heat Problem

[e34m30SF]

Hey everyone,

Did search, but no avail. I have this really bizarre intermittent problem with my heater. It comes up when the engine's at normal op temp. I usually set it to a nice, comfortable 72-73 degrees, with the A/C constantly on. On a slight incline, the heat just completely dies and all I get is cold A/C air. If I crank the sucker to full heat (past the detent), the heat comes back, but if I move it back to 74, it'll blow cold air.

Then, 30 seconds later, it will work just fine. I thought it may have been air in the cooling system, but I've bled the sucker.

Could it be the infamous sword?

3/90 production, so no cabin air filter.

[colo525i]

Sounds like your heater valves are sticking shut. Bang on them w/ a hammer while you have someone turn the dials to change temperature.

[e34m30SF]

They're the item near the drvs firewall, correct? And how much to replace?