Nissan Repair: Heater doesnt work while idle, 2005 nissan frontier, heater control valve

Question
I have a 2005 Nissan frontier.  I have a remote starter and when I let the engine run idle thee heater doesn't work.  But when I dive up the highway it works.  When I let off the gas again it doesn't work.  Any idea what causes this?

Answer
Hi William -

The heater is controlled by engine vacuum. The more RPM's the engine has, the more vacuum -

With that said, I would replace the heater control valve, which should be in line with the heater hose near the firewall. It is probably sticking at low vacuum. I would also check the vacuum hoses related to the valve. Could be kinked or broken.

Hope this helps -
aloha
Calvin