Heat Only Blows Hot When Moving
 

Good Morning,

I have an 09' H3 that has developed an issue which I am hoping to resolve with some help from the experts in this forum.

The blower is working fine, however, the heater only blows hot air when the vehicle is moving. When stopped at lights or moving slow in traffic it blows stone cold air OR slightly warm air. I have also noticed that as it starts to blow hot when I start moving, the heat gauge temporarily rises looking as if it is going to overheat and then quickly falls back to normal. If there are additional details I can provide please let me know...

Any assistance, suggestions, comments will be appreciated.

Thanks,

JY

Have you checked your coolant level?

Hi,
Checked your antifreeze?? Dex cool.....
Thermostat malfunctioning?
Temperature sensor?

Thanks for the replies... The coolant was low, I added some and problem solved.

JY

If it was that low, please ask yourself.... where did it go? Watch that level for a while, check for leaks. Check the oil and Trans fluid to make sure neither has coolant in it ASAP.

I checked both when I added the coolant and both were fine... Does make you wonder where it went. It doesn't smell like coolant when it's running, no unusual exhaust, etc.

I had the exact same issue in my H2 and it took an entire gallon of dexcool, so I knew something was up. Long story short, the radiator was cracked and had to be replaced. Like DocOlds mentioned, coolant leaks in the H3 (and H2) will cause catastrophic issues. I highly recommend you figure out why your coolant was so low