Finally found my solution to lack of heat, intermittent heat, air lock in heater core, etc., etc., etc. When all seems to be functioning OK with the heater system, and still no heat, try back-flushing the heater core. Mine was clogged up and was not passing much coolant. I suspect that the passages are quite narrow and clog easily because not much junk came out when backflushed, but water flow was 10 times more. Now I can't keep my hand in front of the heat vents inside the car because its so hot.

To backflush, force water into the lower fitting of the heater core and allow discharge out the top fitting. DO NOT use much pressure because you may pop the heater core. The water should flow easily when the core is clean. You may need to put radiator cleaner into the core to free up the gunk.

And, there was none of the DREADED air lock in the heater core when I put the coolant back into the engine.

 

hmm... DETAILS.. i may need to try this.. which hoses exactly should i unplug??

 

Remove the two heater hoses at the firewall. Be careful, the pipes that protrude from the heater core through the firewall are a plastic material. To make the job easier, you can use other hose material to extend the connections out to a more convenient location.

I first loosened up the gunk inside the heater core with concentrated radiator cleaner, letting it soak. Then I used a garden hose turned on very low, and LIGHTLY pressed the garden hose against the lower input to the heater core. This limited the amount of pressure inside the heater core until the gunk broke loose, and then I made a better connection AFTER the flow increased.

I first applied the garden hose into the top port, but this didn't clear the restriction. Only after backflushing, (using the bottom heater core connection) did the core clear up.

 

awesome.. im gonna give this a try.. ill let you konw how it goes..

 

I found something that works really good and you don't have to swap any parts or do any manual labor.. I just leave my heating units on ECON until the temp guage gets up about 1/4 of the way, then place it on AUTO for the top vents about half power with the RECIRCULATION button on.. Sounds really simple, but truly does work GREAT..