awkward car heating issue? HELPP?

First: I really don't understand how this could be - heat when on the highway only. But I have to ask one possibly dumb question: Could it be that the fan is spinning when you are on the highway, pumping water through the system? That might be the result of a bad belt. But to be honest, I'm really just guessing.

The fluid level issue I suppose could be a problem, but you said the radiator is full. the overflow reservoir is empty, so you may want to put some coolant in that but that's actually a coolant recovery system.

One last GUESS is that the valve that controls water flow to the heater core may have a bad vacuum hose. At highway speeds (but I'd expect at an idle too) the valve may be seeing enough vacuum to open. I really can't imagine what it may be. Unless recently you moved some hoses and got something plugged into the wrong vacuum port.

Good luck.

'av'a g'day mate.

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im assuming the blower fan is working check coolant level if ok run engine until temp gauge is at normal reading usually in about 10 minutes ( take a ride around the block) then open hood on the right side back by the firewall there will be 2 hoses (3/4 type) feel both if one is much hotter then the other then the heater core is plug up and needs to be replaced

I'd replace the thermostat despite what you think. The job of a thermostat is to maintain temperature at a designated point. If it opens too soon no heat,if it opens too late it overheats. It's the easiest thing you can do or have a shop do. Replace it and have them flush and refill the system to the proper level and your problem will likely be resolved. It's relatively inexpensive and thermostats don't seem to last long anymore so I'd bet that's your problem.

there must be a servo-motor (electric powered) that strikes valves. it must be that some the tooth has been wiped out so it sticks to three factor (ticking noise). Does your cas have automated climate administration? ok, then i'm especially particular approximately this. it must be worn sprocket wheel.. verify his first! It occurs in many situations becuse supplies used for those are no longer of a few extreme high quality. I had comparable situation.

Sounds like all you are getting is forced air when the car is moving.

Do you hear the fan when you turn it on high?

The heater core could be clogged.