Hi,

I am having problems with my 98' Chevrolet Venture front heater - it blows cold-air, it's not winter-cold, but it's not warm. Strange thing that my rear heater blows hot air - as hot it can get. So the problem is front, not back or is it?

When I turn switch from cold to hot I do hear noise that something is happening and, yes rear heater adjusts accordingly, but not the front one...

Do you have any ideas?

Thanks!

 

I didn't know a 98 was vacuum controlled. I'd suspect a vacuum line (if it is vacuum?) off to the selector to the air door. There is a door that moves the air through the heater core that apparently isn't working. Is air blowing through floor when set to heat, windshield when set to defrost?

 

Air is blowing just fine, it's just not hot...

You can feel that it blows weaker when it's switched from cold to heat, but it still blows decently and as I said it's just not hot.

 

Guess what was the problem? It was blown HEAD GASKET...

This issue escalated and temperature gauge started to jump from hot to cold very fast and van started to overheat. In the end we got it tested for free at local radiator shop and they confirmed that it was head gasket.

If you are interested how do they check for it -> mainly using this tool - Combustion Leak Tester: Amazon.com: UVIEW 560000 Combustion Leak Tester: Automotive

Additional checks that can be done:
does your coolant level drops sometimes?
does temperature gauge goes from hot to cold very fast when engine is running?
if you take radiator cap off and start car does it pushes out air bubbles?


Now it's fixed and everything back to normal. Van starts to blow heat after 5minutes of driving. If you do this job make sure you put in good quality gasket, not original GM one...

Cheers