Astro owner

I have a 2003chevy astro van the rear heat has cold air only blowing out wasnt sure how the rear heat worked as opposed to the front ?

Mr Car Guy

I've not had to repair the rear heater on one of these vans but I did own one so I have some idea of how they work.

You have 2 coolant lines running to the rear heater. In one of those lines is a vacuum controlled shut-off valve. That valve will need to have vacuum applied to open when heat is expected. I would turn the heat on and check for vacuum. I can't remember where I saw that valve, I think under the floor. Follow the heater hoses and you should find it. If you have vacuum (engine running) but they lines are not hot then the valve is bad. If you have no vacuum then whatever switch the vacuum source is not working, or you have no vacuum to the switch.

Broken vacuum hoses are nothing new on these vans, common problem. They use plastic lines under the hood and after years of cooking in the heat they break. You may have to remove the inside dog house to access the lines easily.

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1999 AWD Jimmy
1995 AWD Jimmy - RIP, 1989 AWD Jimmy - RIP

I try to learn from other peoples mistakes that I gave advice to.

Astro owner

fixed rear heat ended up being a broken vacuum line. thank you !