Heater air was blowing only luke warm. Replaced radiator hoses, heater hoses, water valve, thermostat, and reservoir hose. Flushed the radiator, engine block, and heater core. Heater core was gunked up, but now lets water flow freely. Now the heater functions better, but not as well as it should.

Upon further investigation, I found two anomalies. The first is that the heater valve doesn't open. If I remove the vacuum control line to the valve at the firewall and suck on it, then the valve opens properly. So I'm not getting vacuum to the port when the heater is on and the engine is hot. Is this indicative of a vacuum failure (bellows problem?) or the climate control computer?

Also, I detected a strong air flow in the engine compartment. I traced it to an air leak where the A/C lines go through the firewall. It looks like there is a black gooky substance used as a sealer around the A/C high and low pressure lines where they go through the firewall and that it is coming loose. Can I just squirt some silicone around the A/C tubes to reseal it, or is there a better, preferred method for sealing it?

I'm assuming the reduced air flow (and performance) from the heater vents is due to the pressure loss here at the firewall.

Thanks for all help,
Robert